Food is a primary factor affecting the growth and survival of juvenile western rock lobsters in nursery areas. Determining how far juveniles travel when searching for food is essential in determining the size of area foraged and how much food is potentially available to them. Knowledge of foraging patterns and feeding activity of juvenile western rock lobsters is, therefore, required to understand their ecology.

Studies on natural foraging activity of rock lobsters are difficult. The animals feed at night and it is only possible for divers to observe a few animals. In addition, the natural behavior of rock lobsters is affected by the presence of divers. The lobsters hide from the divers in the seagrass beds instead of foraging.

Phillips et al. (1984) developed a method of remotely tracking juvenile western rock lobsters using electromagnetic tags. Natural foraging distances and activity can be determined by this method, enabling researchers to monitor the position of the tagged lobsters throughout the night.

Food is a primary factor affecting the growth and survival of juvenile western rock lobsters in nursery areas. Determining how far juveniles travel when searching for food is essential in determining the size of area foraged and how much food is potentially available to them. Knowledge of foraging patterns and feeding activity of juvenile western rock lobsters is, therefore, required to understand their ecology.

Studies on natural foraging activity of rock lobsters are difficult. The animals feed at night and it is only possible for divers to observe a few animals. In addition, the natural behavior of rock lobsters is affected by the presence of divers. The lobsters hide from the divers in the seagrass beds instead of foraging.

Phillips et al. (1984) developed a method of remotely tracking juvenile western rock lobsters using electromagnetic tags. Natural foraging distances and activity can be determined by this method, enabling researchers to monitor the position of the tagged lobsters throughout the night.

Food is a primary factor affecting the growth and survival of juvenile western rock lobsters in nursery areas. Determining how far juveniles travel when searching for food is essential in determining the size of area foraged and how much food is potentially available to them. Knowledge of foraging patterns and feeding activity of juvenile western rock lobsters is, therefore, required to understand their ecology.

Studies on natural foraging activity of rock lobsters are difficult. The animals feed at night and it is only possible for divers to observe a few animals. In addition, the natural behavior of rock lobsters is affected by the presence of divers. The lobsters hide from the divers in the seagrass beds instead of foraging.

Phillips et al. (1984) developed a method of remotely tracking juvenile western rock lobsters using electromagnetic tags. Natural foraging distances and activity can be determined by this method, enabling researchers to monitor the position of the tagged lobsters throughout the night.

Food is a primary factor affecting the growth and survival of juvenile western rock lobsters in nursery areas. Determining how far juveniles travel when searching for food is essential in determining the size of area foraged and how much food is potentially available to them. Knowledge of foraging patterns and feeding activity of juvenile western rock lobsters is, therefore, required to understand their ecology.

Studies on natural foraging activity of rock lobsters are difficult. The animals feed at night and it is only possible for divers to observe a few animals. In addition, the natural behavior of rock lobsters is affected by the presence of divers. The lobsters hide from the divers in the seagrass beds instead of foraging.

Phillips et al. (1984) developed a method of remotely tracking juvenile western rock lobsters using electromagnetic tags. Natural foraging distances and activity can be determined by this method, enabling researchers to monitor the position of the tagged lobsters throughout the night.

Food is a primary factor affecting the growth and survival of juvenile western rock lobsters in nursery areas. Determining how far juveniles travel when searching for food is essential in determining the size of area foraged and how much food is potentially available to them. Knowledge of foraging patterns and feeding activity of juvenile western rock lobsters is, therefore, required to understand their ecology.

Studies on natural foraging activity of rock lobsters are difficult. The animals feed at night and it is only possible for divers to observe a few animals. In addition, the natural behavior of rock lobsters is affected by the presence of divers. The lobsters hide from the divers in the seagrass beds instead of foraging.

Phillips et al. (1984) developed a method of remotely tracking juvenile western rock lobsters using electromagnetic tags. Natural foraging distances and activity can be determined by this method, enabling researchers to monitor the position of the tagged lobsters throughout the night.

Food is a primary factor affecting the growth and survival of juvenile western rock lobsters in nursery areas. Determining how far juveniles travel when searching for food is essential in determining the size of area foraged and how much food is potentially available to them. Knowledge of foraging patterns and feeding activity of juvenile western rock lobsters is, therefore, required to understand their ecology.

Studies on natural foraging activity of rock lobsters are difficult. The animals feed at night and it is only possible for divers to observe a few animals. In addition, the natural behavior of rock lobsters is affected by the presence of divers. The lobsters hide from the divers in the seagrass beds instead of foraging.

Phillips et al. (1984) developed a method of remotely tracking juvenile western rock lobsters using electromagnetic tags. Natural foraging distances and activity can be determined by this method, enabling researchers to monitor the position of the tagged lobsters throughout the night.

Food is a primary factor affecting the growth and survival of juvenile western rock lobsters in nursery areas. Determining how far juveniles travel when searching for food is essential in determining the size of area foraged and how much food is potentially available to them. Knowledge of foraging patterns and feeding activity of juvenile western rock lobsters is, therefore, required to understand their ecology.

Studies on natural foraging activity of rock lobsters are difficult. The animals feed at night and it is only possible for divers to observe a few animals. In addition, the natural behavior of rock lobsters is affected by the presence of divers. The lobsters hide from the divers in the seagrass beds instead of foraging.

Phillips et al. (1984) developed a method of remotely tracking juvenile western rock lobsters using electromagnetic tags. Natural foraging distances and activity can be determined by this method, enabling researchers to monitor the position of the tagged lobsters throughout the night.

Food is a primary factor affecting the growth and survival of juvenile western rock lobsters in nursery areas. Determining how far juveniles travel when searching for food is essential in determining the size of area foraged and how much food is potentially available to them. Knowledge of foraging patterns and feeding activity of juvenile western rock lobsters is, therefore, required to understand their ecology.

Studies on natural foraging activity of rock lobsters are difficult. The animals feed at night and it is only possible for divers to observe a few animals. In addition, the natural behavior of rock lobsters is affected by the presence of divers. The lobsters hide from the divers in the seagrass beds instead of foraging.

Phillips et al. (1984) developed a method of remotely tracking juvenile western rock lobsters using electromagnetic tags. Natural foraging distances and activity can be determined by this method, enabling researchers to monitor the position of the tagged lobsters throughout the night.

Food is a primary factor affecting the growth and survival of juvenile western rock lobsters in nursery areas. Determining how far juveniles travel when searching for food is essential in determining the size of area foraged and how much food is potentially available to them. Knowledge of foraging patterns and feeding activity of juvenile western rock lobsters is, therefore, required to understand their ecology.

Studies on natural foraging activity of rock lobsters are difficult. The animals feed at night and it is only possible for divers to observe a few animals. In addition, the natural behavior of rock lobsters is affected by the presence of divers. The lobsters hide from the divers in the seagrass beds instead of foraging.

Phillips et al. (1984) developed a method of remotely tracking juvenile western rock lobsters using electromagnetic tags. Natural foraging distances and activity can be determined by this method, enabling researchers to monitor the position of the tagged lobsters throughout the night.

Food is a primary factor affecting the growth and survival of juvenile western rock lobsters in nursery areas. Determining how far juveniles travel when searching for food is essential in determining the size of area foraged and how much food is potentially available to them. Knowledge of foraging patterns and feeding activity of juvenile western rock lobsters is, therefore, required to understand their ecology.

Studies on natural foraging activity of rock lobsters are difficult. The animals feed at night and it is only possible for divers to observe a few animals. In addition, the natural behavior of rock lobsters is affected by the presence of divers. The lobsters hide from the divers in the seagrass beds instead of foraging.

Phillips et al. (1984) developed a method of remotely tracking juvenile western rock lobsters using electromagnetic tags. Natural foraging distances and activity can be determined by this method, enabling researchers to monitor the position of the tagged lobsters throughout the night.

Food is a primary factor affecting the growth and survival of juvenile western rock lobsters in nursery areas. Determining how far juveniles travel when searching for food is essential in determining the size of area foraged and how much food is potentially available to them. Knowledge of foraging patterns and feeding activity of juvenile western rock lobsters is, therefore, required to understand their ecology.

Studies on natural foraging activity of rock lobsters are difficult. The animals feed at night and it is only possible for divers to observe a few animals. In addition, the natural behavior of rock lobsters is affected by the presence of divers. The lobsters hide from the divers in the seagrass beds instead of foraging.

Phillips et al. (1984) developed a method of remotely tracking juvenile western rock lobsters using electromagnetic tags. Natural foraging distances and activity can be determined by this method, enabling researchers to monitor the position of the tagged lobsters throughout the night.

Food is a primary factor affecting the growth and survival of juvenile western rock lobsters in nursery areas. Determining how far juveniles travel when searching for food is essential in determining the size of area foraged and how much food is potentially available to them. Knowledge of foraging patterns and feeding activity of juvenile western rock lobsters is, therefore, required to understand their ecology.

Studies on natural foraging activity of rock lobsters are difficult. The animals feed at night and it is only possible for divers to observe a few animals. In addition, the natural behavior of rock lobsters is affected by the presence of divers. The lobsters hide from the divers in the seagrass beds instead of foraging.

Phillips et al. (1984) developed a method of remotely tracking juvenile western rock lobsters using electromagnetic tags. Natural foraging distances and activity can be determined by this method, enabling researchers to monitor the position of the tagged lobsters throughout the night.

Food is a primary factor affecting the growth and survival of juvenile western rock lobsters in nursery areas. Determining how far juveniles travel when searching for food is essential in determining the size of area foraged and how much food is potentially available to them. Knowledge of foraging patterns and feeding activity of juvenile western rock lobsters is, therefore, required to understand their ecology.

Studies on natural foraging activity of rock lobsters are difficult. The animals feed at night and it is only possible for divers to observe a few animals. In addition, the natural behavior of rock lobsters is affected by the presence of divers. The lobsters hide from the divers in the seagrass beds instead of foraging.

Phillips et al. (1984) developed a method of remotely tracking juvenile western rock lobsters using electromagnetic tags. Natural foraging distances and activity can be determined by this method, enabling researchers to monitor the position of the tagged lobsters throughout the night.

Food is a primary factor affecting the growth and survival of juvenile western rock lobsters in nursery areas. Determining how far juveniles travel when searching for food is essential in determining the size of area foraged and how much food is potentially available to them. Knowledge of foraging patterns and feeding activity of juvenile western rock lobsters is, therefore, required to understand their ecology.

Studies on natural foraging activity of rock lobsters are difficult. The animals feed at night and it is only possible for divers to observe a few animals. In addition, the natural behavior of rock lobsters is affected by the presence of divers. The lobsters hide from the divers in the seagrass beds instead of foraging.

Phillips et al. (1984) developed a method of remotely tracking juvenile western rock lobsters using electromagnetic tags. Natural foraging distances and activity can be determined by this method, enabling researchers to monitor the position of the tagged lobsters throughout the night.

Food is a primary factor affecting the growth and survival of juvenile western rock lobsters in nursery areas. Determining how far juveniles travel when searching for food is essential in determining the size of area foraged and how much food is potentially available to them. Knowledge of foraging patterns and feeding activity of juvenile western rock lobsters is, therefore, required to understand their ecology.

Studies on natural foraging activity of rock lobsters are difficult. The animals feed at night and it is only possible for divers to observe a few animals. In addition, the natural behavior of rock lobsters is affected by the presence of divers. The lobsters hide from the divers in the seagrass beds instead of foraging.

Phillips et al. (1984) developed a method of remotely tracking juvenile western rock lobsters using electromagnetic tags. Natural foraging distances and activity can be determined by this method, enabling researchers to monitor the position of the tagged lobsters throughout the night.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

Patterns of ontogenetic variation in the composition of the otoliths of southern Bluefin tuna (SBT), Thunnus maccoyii, strongly suggested that the concentrations f some elements (and particularly strontium) varied episodically, and probably annually. This suggested that counting the numbers of peaks and troughs in strontium concentrations, as measured across the entire growth axis of a vertebra o otolith, could be an accurate and precise way to determine the ages of fully mature SBT. This suggestion was tested by 1) determining experimentally the extent to which otolith composition varies seasonally, 2) comparing ages estimated using otolith composition with those estimated for the same fish by conventional hard-part aging, 3) determining the extent to which different observers examining the same data would agree on the age of a given specimen (which is a measure of the inherent imprecision of the otolith chemical approach), and 4) attempting to validate annual cycles of deposition by measuring changes in the composition of otolith margins for samples collected over an 18 month period.

The following report is a description of the two FIR TA projects (85/85 & 89/13) which examined recruitment processes in penaeids at Albatross Bay in the northeastern Gulf of Carpentaria over the years 1985 to 1992. The aim of the first of the two projects was to identify the main factors which control the recruitment of prawns, while the aim of the second project was to build on the results on the first to provide managers with explanations for declines in commercial catches that had been experienced in the fishery.

The work was focused in three main areas: measuring year-to-year variation in numbers of the main life history stages (eggs, larvae, juveniles and adults in the Albatross Bay region) and correlating the abundances with changes in the environment; measuring the year-to-year variation in the extent of predation by fish on juvenile and adult prawns; and examining relationships between commercial fishery catches throughout the Northern Prawn Fishery and meteorological data.

The results of the projects have enabled us to better define the life history dynamics of the banana prawn Penaeus merguiensis and, to a lesser extent, the grooved tiger prawn Penaeus semisulcatus. Life cycles of both species were found to be based on two cohorts per year. Comparison with P. merguiensis life cycles throughout the Indo-West Pacific region has shown that two cohorts per year was the common pattern, and that the relative contribution to offshore commercial fisheries of each cohort in the various regions wa􀁴 governed to a large extent by the local pattern of rainfall. In the case of P. merguiensis in Albatross Bay, differential mortality results in only one of these cohorts contributing significantly to the commercial fishery.

The following report is a description of the two FIR TA projects (85/85 & 89/13) which examined recruitment processes in penaeids at Albatross Bay in the northeastern Gulf of Carpentaria over the years 1985 to 1992. The aim of the first of the two projects was to identify the main factors which control the recruitment of prawns, while the aim of the second project was to build on the results on the first to provide managers with explanations for declines in commercial catches that had been experienced in the fishery.

The work was focused in three main areas: measuring year-to-year variation in numbers of the main life history stages (eggs, larvae, juveniles and adults in the Albatross Bay region) and correlating the abundances with changes in the environment; measuring the year-to-year variation in the extent of predation by fish on juvenile and adult prawns; and examining relationships between commercial fishery catches throughout the Northern Prawn Fishery and meteorological data.

The results of the projects have enabled us to better define the life history dynamics of the banana prawn Penaeus merguiensis and, to a lesser extent, the grooved tiger prawn Penaeus semisulcatus. Life cycles of both species were found to be based on two cohorts per year. Comparison with P. merguiensis life cycles throughout the Indo-West Pacific region has shown that two cohorts per year was the common pattern, and that the relative contribution to offshore commercial fisheries of each cohort in the various regions wa􀁴 governed to a large extent by the local pattern of rainfall. In the case of P. merguiensis in Albatross Bay, differential mortality results in only one of these cohorts contributing significantly to the commercial fishery.

The following report is a description of the two FIR TA projects (85/85 & 89/13) which examined recruitment processes in penaeids at Albatross Bay in the northeastern Gulf of Carpentaria over the years 1985 to 1992. The aim of the first of the two projects was to identify the main factors which control the recruitment of prawns, while the aim of the second project was to build on the results on the first to provide managers with explanations for declines in commercial catches that had been experienced in the fishery.

The work was focused in three main areas: measuring year-to-year variation in numbers of the main life history stages (eggs, larvae, juveniles and adults in the Albatross Bay region) and correlating the abundances with changes in the environment; measuring the year-to-year variation in the extent of predation by fish on juvenile and adult prawns; and examining relationships between commercial fishery catches throughout the Northern Prawn Fishery and meteorological data.

The results of the projects have enabled us to better define the life history dynamics of the banana prawn Penaeus merguiensis and, to a lesser extent, the grooved tiger prawn Penaeus semisulcatus. Life cycles of both species were found to be based on two cohorts per year. Comparison with P. merguiensis life cycles throughout the Indo-West Pacific region has shown that two cohorts per year was the common pattern, and that the relative contribution to offshore commercial fisheries of each cohort in the various regions wa􀁴 governed to a large extent by the local pattern of rainfall. In the case of P. merguiensis in Albatross Bay, differential mortality results in only one of these cohorts contributing significantly to the commercial fishery.

The following report is a description of the two FIR TA projects (85/85 & 89/13) which examined recruitment processes in penaeids at Albatross Bay in the northeastern Gulf of Carpentaria over the years 1985 to 1992. The aim of the first of the two projects was to identify the main factors which control the recruitment of prawns, while the aim of the second project was to build on the results on the first to provide managers with explanations for declines in commercial catches that had been experienced in the fishery.

The work was focused in three main areas: measuring year-to-year variation in numbers of the main life history stages (eggs, larvae, juveniles and adults in the Albatross Bay region) and correlating the abundances with changes in the environment; measuring the year-to-year variation in the extent of predation by fish on juvenile and adult prawns; and examining relationships between commercial fishery catches throughout the Northern Prawn Fishery and meteorological data.

The results of the projects have enabled us to better define the life history dynamics of the banana prawn Penaeus merguiensis and, to a lesser extent, the grooved tiger prawn Penaeus semisulcatus. Life cycles of both species were found to be based on two cohorts per year. Comparison with P. merguiensis life cycles throughout the Indo-West Pacific region has shown that two cohorts per year was the common pattern, and that the relative contribution to offshore commercial fisheries of each cohort in the various regions wa􀁴 governed to a large extent by the local pattern of rainfall. In the case of P. merguiensis in Albatross Bay, differential mortality results in only one of these cohorts contributing significantly to the commercial fishery.

The following report is a description of the two FIR TA projects (85/85 & 89/13) which examined recruitment processes in penaeids at Albatross Bay in the northeastern Gulf of Carpentaria over the years 1985 to 1992. The aim of the first of the two projects was to identify the main factors which control the recruitment of prawns, while the aim of the second project was to build on the results on the first to provide managers with explanations for declines in commercial catches that had been experienced in the fishery.

The work was focused in three main areas: measuring year-to-year variation in numbers of the main life history stages (eggs, larvae, juveniles and adults in the Albatross Bay region) and correlating the abundances with changes in the environment; measuring the year-to-year variation in the extent of predation by fish on juvenile and adult prawns; and examining relationships between commercial fishery catches throughout the Northern Prawn Fishery and meteorological data.

The results of the projects have enabled us to better define the life history dynamics of the banana prawn Penaeus merguiensis and, to a lesser extent, the grooved tiger prawn Penaeus semisulcatus. Life cycles of both species were found to be based on two cohorts per year. Comparison with P. merguiensis life cycles throughout the Indo-West Pacific region has shown that two cohorts per year was the common pattern, and that the relative contribution to offshore commercial fisheries of each cohort in the various regions wa􀁴 governed to a large extent by the local pattern of rainfall. In the case of P. merguiensis in Albatross Bay, differential mortality results in only one of these cohorts contributing significantly to the commercial fishery.

The following report is a description of the two FIR TA projects (85/85 & 89/13) which examined recruitment processes in penaeids at Albatross Bay in the northeastern Gulf of Carpentaria over the years 1985 to 1992. The aim of the first of the two projects was to identify the main factors which control the recruitment of prawns, while the aim of the second project was to build on the results on the first to provide managers with explanations for declines in commercial catches that had been experienced in the fishery.

The work was focused in three main areas: measuring year-to-year variation in numbers of the main life history stages (eggs, larvae, juveniles and adults in the Albatross Bay region) and correlating the abundances with changes in the environment; measuring the year-to-year variation in the extent of predation by fish on juvenile and adult prawns; and examining relationships between commercial fishery catches throughout the Northern Prawn Fishery and meteorological data.

The results of the projects have enabled us to better define the life history dynamics of the banana prawn Penaeus merguiensis and, to a lesser extent, the grooved tiger prawn Penaeus semisulcatus. Life cycles of both species were found to be based on two cohorts per year. Comparison with P. merguiensis life cycles throughout the Indo-West Pacific region has shown that two cohorts per year was the common pattern, and that the relative contribution to offshore commercial fisheries of each cohort in the various regions wa􀁴 governed to a large extent by the local pattern of rainfall. In the case of P. merguiensis in Albatross Bay, differential mortality results in only one of these cohorts contributing significantly to the commercial fishery.

The following report is a description of the two FIR TA projects (85/85 & 89/13) which examined recruitment processes in penaeids at Albatross Bay in the northeastern Gulf of Carpentaria over the years 1985 to 1992. The aim of the first of the two projects was to identify the main factors which control the recruitment of prawns, while the aim of the second project was to build on the results on the first to provide managers with explanations for declines in commercial catches that had been experienced in the fishery.

The work was focused in three main areas: measuring year-to-year variation in numbers of the main life history stages (eggs, larvae, juveniles and adults in the Albatross Bay region) and correlating the abundances with changes in the environment; measuring the year-to-year variation in the extent of predation by fish on juvenile and adult prawns; and examining relationships between commercial fishery catches throughout the Northern Prawn Fishery and meteorological data.

The results of the projects have enabled us to better define the life history dynamics of the banana prawn Penaeus merguiensis and, to a lesser extent, the grooved tiger prawn Penaeus semisulcatus. Life cycles of both species were found to be based on two cohorts per year. Comparison with P. merguiensis life cycles throughout the Indo-West Pacific region has shown that two cohorts per year was the common pattern, and that the relative contribution to offshore commercial fisheries of each cohort in the various regions wa􀁴 governed to a large extent by the local pattern of rainfall. In the case of P. merguiensis in Albatross Bay, differential mortality results in only one of these cohorts contributing significantly to the commercial fishery.

The following report is a description of the two FIR TA projects (85/85 & 89/13) which examined recruitment processes in penaeids at Albatross Bay in the northeastern Gulf of Carpentaria over the years 1985 to 1992. The aim of the first of the two projects was to identify the main factors which control the recruitment of prawns, while the aim of the second project was to build on the results on the first to provide managers with explanations for declines in commercial catches that had been experienced in the fishery.

The work was focused in three main areas: measuring year-to-year variation in numbers of the main life history stages (eggs, larvae, juveniles and adults in the Albatross Bay region) and correlating the abundances with changes in the environment; measuring the year-to-year variation in the extent of predation by fish on juvenile and adult prawns; and examining relationships between commercial fishery catches throughout the Northern Prawn Fishery and meteorological data.

The results of the projects have enabled us to better define the life history dynamics of the banana prawn Penaeus merguiensis and, to a lesser extent, the grooved tiger prawn Penaeus semisulcatus. Life cycles of both species were found to be based on two cohorts per year. Comparison with P. merguiensis life cycles throughout the Indo-West Pacific region has shown that two cohorts per year was the common pattern, and that the relative contribution to offshore commercial fisheries of each cohort in the various regions wa􀁴 governed to a large extent by the local pattern of rainfall. In the case of P. merguiensis in Albatross Bay, differential mortality results in only one of these cohorts contributing significantly to the commercial fishery.

The following report is a description of the two FIR TA projects (85/85 & 89/13) which examined recruitment processes in penaeids at Albatross Bay in the northeastern Gulf of Carpentaria over the years 1985 to 1992. The aim of the first of the two projects was to identify the main factors which control the recruitment of prawns, while the aim of the second project was to build on the results on the first to provide managers with explanations for declines in commercial catches that had been experienced in the fishery.

The work was focused in three main areas: measuring year-to-year variation in numbers of the main life history stages (eggs, larvae, juveniles and adults in the Albatross Bay region) and correlating the abundances with changes in the environment; measuring the year-to-year variation in the extent of predation by fish on juvenile and adult prawns; and examining relationships between commercial fishery catches throughout the Northern Prawn Fishery and meteorological data.

The results of the projects have enabled us to better define the life history dynamics of the banana prawn Penaeus merguiensis and, to a lesser extent, the grooved tiger prawn Penaeus semisulcatus. Life cycles of both species were found to be based on two cohorts per year. Comparison with P. merguiensis life cycles throughout the Indo-West Pacific region has shown that two cohorts per year was the common pattern, and that the relative contribution to offshore commercial fisheries of each cohort in the various regions wa􀁴 governed to a large extent by the local pattern of rainfall. In the case of P. merguiensis in Albatross Bay, differential mortality results in only one of these cohorts contributing significantly to the commercial fishery.

The following report is a description of the two FIR TA projects (85/85 & 89/13) which examined recruitment processes in penaeids at Albatross Bay in the northeastern Gulf of Carpentaria over the years 1985 to 1992. The aim of the first of the two projects was to identify the main factors which control the recruitment of prawns, while the aim of the second project was to build on the results on the first to provide managers with explanations for declines in commercial catches that had been experienced in the fishery.

The work was focused in three main areas: measuring year-to-year variation in numbers of the main life history stages (eggs, larvae, juveniles and adults in the Albatross Bay region) and correlating the abundances with changes in the environment; measuring the year-to-year variation in the extent of predation by fish on juvenile and adult prawns; and examining relationships between commercial fishery catches throughout the Northern Prawn Fishery and meteorological data.

The results of the projects have enabled us to better define the life history dynamics of the banana prawn Penaeus merguiensis and, to a lesser extent, the grooved tiger prawn Penaeus semisulcatus. Life cycles of both species were found to be based on two cohorts per year. Comparison with P. merguiensis life cycles throughout the Indo-West Pacific region has shown that two cohorts per year was the common pattern, and that the relative contribution to offshore commercial fisheries of each cohort in the various regions wa􀁴 governed to a large extent by the local pattern of rainfall. In the case of P. merguiensis in Albatross Bay, differential mortality results in only one of these cohorts contributing significantly to the commercial fishery.

The following report is a description of the two FIR TA projects (85/85 & 89/13) which examined recruitment processes in penaeids at Albatross Bay in the northeastern Gulf of Carpentaria over the years 1985 to 1992. The aim of the first of the two projects was to identify the main factors which control the recruitment of prawns, while the aim of the second project was to build on the results on the first to provide managers with explanations for declines in commercial catches that had been experienced in the fishery.

The work was focused in three main areas: measuring year-to-year variation in numbers of the main life history stages (eggs, larvae, juveniles and adults in the Albatross Bay region) and correlating the abundances with changes in the environment; measuring the year-to-year variation in the extent of predation by fish on juvenile and adult prawns; and examining relationships between commercial fishery catches throughout the Northern Prawn Fishery and meteorological data.

The results of the projects have enabled us to better define the life history dynamics of the banana prawn Penaeus merguiensis and, to a lesser extent, the grooved tiger prawn Penaeus semisulcatus. Life cycles of both species were found to be based on two cohorts per year. Comparison with P. merguiensis life cycles throughout the Indo-West Pacific region has shown that two cohorts per year was the common pattern, and that the relative contribution to offshore commercial fisheries of each cohort in the various regions wa􀁴 governed to a large extent by the local pattern of rainfall. In the case of P. merguiensis in Albatross Bay, differential mortality results in only one of these cohorts contributing significantly to the commercial fishery.

The following report is a description of the two FIR TA projects (85/85 & 89/13) which examined recruitment processes in penaeids at Albatross Bay in the northeastern Gulf of Carpentaria over the years 1985 to 1992. The aim of the first of the two projects was to identify the main factors which control the recruitment of prawns, while the aim of the second project was to build on the results on the first to provide managers with explanations for declines in commercial catches that had been experienced in the fishery.

The work was focused in three main areas: measuring year-to-year variation in numbers of the main life history stages (eggs, larvae, juveniles and adults in the Albatross Bay region) and correlating the abundances with changes in the environment; measuring the year-to-year variation in the extent of predation by fish on juvenile and adult prawns; and examining relationships between commercial fishery catches throughout the Northern Prawn Fishery and meteorological data.

The results of the projects have enabled us to better define the life history dynamics of the banana prawn Penaeus merguiensis and, to a lesser extent, the grooved tiger prawn Penaeus semisulcatus. Life cycles of both species were found to be based on two cohorts per year. Comparison with P. merguiensis life cycles throughout the Indo-West Pacific region has shown that two cohorts per year was the common pattern, and that the relative contribution to offshore commercial fisheries of each cohort in the various regions wa􀁴 governed to a large extent by the local pattern of rainfall. In the case of P. merguiensis in Albatross Bay, differential mortality results in only one of these cohorts contributing significantly to the commercial fishery.

The following report is a description of the two FIR TA projects (85/85 & 89/13) which examined recruitment processes in penaeids at Albatross Bay in the northeastern Gulf of Carpentaria over the years 1985 to 1992. The aim of the first of the two projects was to identify the main factors which control the recruitment of prawns, while the aim of the second project was to build on the results on the first to provide managers with explanations for declines in commercial catches that had been experienced in the fishery.

The work was focused in three main areas: measuring year-to-year variation in numbers of the main life history stages (eggs, larvae, juveniles and adults in the Albatross Bay region) and correlating the abundances with changes in the environment; measuring the year-to-year variation in the extent of predation by fish on juvenile and adult prawns; and examining relationships between commercial fishery catches throughout the Northern Prawn Fishery and meteorological data.

The results of the projects have enabled us to better define the life history dynamics of the banana prawn Penaeus merguiensis and, to a lesser extent, the grooved tiger prawn Penaeus semisulcatus. Life cycles of both species were found to be based on two cohorts per year. Comparison with P. merguiensis life cycles throughout the Indo-West Pacific region has shown that two cohorts per year was the common pattern, and that the relative contribution to offshore commercial fisheries of each cohort in the various regions wa􀁴 governed to a large extent by the local pattern of rainfall. In the case of P. merguiensis in Albatross Bay, differential mortality results in only one of these cohorts contributing significantly to the commercial fishery.

The following report is a description of the two FIR TA projects (85/85 & 89/13) which examined recruitment processes in penaeids at Albatross Bay in the northeastern Gulf of Carpentaria over the years 1985 to 1992. The aim of the first of the two projects was to identify the main factors which control the recruitment of prawns, while the aim of the second project was to build on the results on the first to provide managers with explanations for declines in commercial catches that had been experienced in the fishery.

The work was focused in three main areas: measuring year-to-year variation in numbers of the main life history stages (eggs, larvae, juveniles and adults in the Albatross Bay region) and correlating the abundances with changes in the environment; measuring the year-to-year variation in the extent of predation by fish on juvenile and adult prawns; and examining relationships between commercial fishery catches throughout the Northern Prawn Fishery and meteorological data.

The results of the projects have enabled us to better define the life history dynamics of the banana prawn Penaeus merguiensis and, to a lesser extent, the grooved tiger prawn Penaeus semisulcatus. Life cycles of both species were found to be based on two cohorts per year. Comparison with P. merguiensis life cycles throughout the Indo-West Pacific region has shown that two cohorts per year was the common pattern, and that the relative contribution to offshore commercial fisheries of each cohort in the various regions wa􀁴 governed to a large extent by the local pattern of rainfall. In the case of P. merguiensis in Albatross Bay, differential mortality results in only one of these cohorts contributing significantly to the commercial fishery.

The following report is a description of the two FIR TA projects (85/85 & 89/13) which examined recruitment processes in penaeids at Albatross Bay in the northeastern Gulf of Carpentaria over the years 1985 to 1992. The aim of the first of the two projects was to identify the main factors which control the recruitment of prawns, while the aim of the second project was to build on the results on the first to provide managers with explanations for declines in commercial catches that had been experienced in the fishery.

The work was focused in three main areas: measuring year-to-year variation in numbers of the main life history stages (eggs, larvae, juveniles and adults in the Albatross Bay region) and correlating the abundances with changes in the environment; measuring the year-to-year variation in the extent of predation by fish on juvenile and adult prawns; and examining relationships between commercial fishery catches throughout the Northern Prawn Fishery and meteorological data.

The results of the projects have enabled us to better define the life history dynamics of the banana prawn Penaeus merguiensis and, to a lesser extent, the grooved tiger prawn Penaeus semisulcatus. Life cycles of both species were found to be based on two cohorts per year. Comparison with P. merguiensis life cycles throughout the Indo-West Pacific region has shown that two cohorts per year was the common pattern, and that the relative contribution to offshore commercial fisheries of each cohort in the various regions wa􀁴 governed to a large extent by the local pattern of rainfall. In the case of P. merguiensis in Albatross Bay, differential mortality results in only one of these cohorts contributing significantly to the commercial fishery.