Australia’s tropical snapper fisheries harvest six main Lutjanid species. They are the Crimson, Saddletail, and Goldband snappers, Red Emperor, Golden snapper and Mangrove Jack. These fish live up to 40 years of age, weigh up to five to ten kilograms and are highly valued for commercial marketing. The fisheries operate in tropical offshore waters across northern Australia from the Kimberley coast to the Gulf of Carpentaria. The fisheries are primarily commercial using demersal trawl, trap and line fishing gear. The fisheries have a long and varied history of foreign and domestic exploitation. Indicative foreign harvests were two to five kilotonnes per year up to 1990. After 1990, foreign vessel permits were removed and domestic fishing expanded landing in the order of two to three kilotonnes of tropical snappers annually.

In 2007, NAFC listed tropical snapper research as a priority. Past assessments and management settings required revision. New monitoring data on snapper abundance and age composition were needed for assessment of stock status and contemporary management procedures. In response, northern fisheries jurisdictions and the FRDC commissioned tactical research to develop a survey / observer structured fishery monitoring program and critically evaluate the potential use of data. A total of 39 data sets and a range of analyses were used in this process.

Statistical analyses of commercial fishery catch rates quantified variances to establish abundance indicators from structured monitoring. The variances were used to calculate the number of survey / observer days required to monitor tropical snapper catch rates (e.g., standardised number of fish caught per unit area swept by trawling). This result was required to ensure accurate monitoring of catch rates and fish ages so the data were directly aligned for estimation of fishing mortality or, possibly, biomass.

Keywords: Age frequencies, Catch curves, Catch rate standardisation, Fishery management, Lutjanidae, Monitoring, Population modelling, Simulation, Tropical snapper.

Australia’s tropical snapper fisheries harvest six main Lutjanid species. They are the Crimson, Saddletail, and Goldband snappers, Red Emperor, Golden snapper and Mangrove Jack. These fish live up to 40 years of age, weigh up to five to ten kilograms and are highly valued for commercial marketing. The fisheries operate in tropical offshore waters across northern Australia from the Kimberley coast to the Gulf of Carpentaria. The fisheries are primarily commercial using demersal trawl, trap and line fishing gear. The fisheries have a long and varied history of foreign and domestic exploitation. Indicative foreign harvests were two to five kilotonnes per year up to 1990. After 1990, foreign vessel permits were removed and domestic fishing expanded landing in the order of two to three kilotonnes of tropical snappers annually.

In 2007, NAFC listed tropical snapper research as a priority. Past assessments and management settings required revision. New monitoring data on snapper abundance and age composition were needed for assessment of stock status and contemporary management procedures. In response, northern fisheries jurisdictions and the FRDC commissioned tactical research to develop a survey / observer structured fishery monitoring program and critically evaluate the potential use of data. A total of 39 data sets and a range of analyses were used in this process.

Statistical analyses of commercial fishery catch rates quantified variances to establish abundance indicators from structured monitoring. The variances were used to calculate the number of survey / observer days required to monitor tropical snapper catch rates (e.g., standardised number of fish caught per unit area swept by trawling). This result was required to ensure accurate monitoring of catch rates and fish ages so the data were directly aligned for estimation of fishing mortality or, possibly, biomass.

Keywords: Age frequencies, Catch curves, Catch rate standardisation, Fishery management, Lutjanidae, Monitoring, Population modelling, Simulation, Tropical snapper.

Australia’s tropical snapper fisheries harvest six main Lutjanid species. They are the Crimson, Saddletail, and Goldband snappers, Red Emperor, Golden snapper and Mangrove Jack. These fish live up to 40 years of age, weigh up to five to ten kilograms and are highly valued for commercial marketing. The fisheries operate in tropical offshore waters across northern Australia from the Kimberley coast to the Gulf of Carpentaria. The fisheries are primarily commercial using demersal trawl, trap and line fishing gear. The fisheries have a long and varied history of foreign and domestic exploitation. Indicative foreign harvests were two to five kilotonnes per year up to 1990. After 1990, foreign vessel permits were removed and domestic fishing expanded landing in the order of two to three kilotonnes of tropical snappers annually.

In 2007, NAFC listed tropical snapper research as a priority. Past assessments and management settings required revision. New monitoring data on snapper abundance and age composition were needed for assessment of stock status and contemporary management procedures. In response, northern fisheries jurisdictions and the FRDC commissioned tactical research to develop a survey / observer structured fishery monitoring program and critically evaluate the potential use of data. A total of 39 data sets and a range of analyses were used in this process.

Statistical analyses of commercial fishery catch rates quantified variances to establish abundance indicators from structured monitoring. The variances were used to calculate the number of survey / observer days required to monitor tropical snapper catch rates (e.g., standardised number of fish caught per unit area swept by trawling). This result was required to ensure accurate monitoring of catch rates and fish ages so the data were directly aligned for estimation of fishing mortality or, possibly, biomass.

Keywords: Age frequencies, Catch curves, Catch rate standardisation, Fishery management, Lutjanidae, Monitoring, Population modelling, Simulation, Tropical snapper.

Australia’s tropical snapper fisheries harvest six main Lutjanid species. They are the Crimson, Saddletail, and Goldband snappers, Red Emperor, Golden snapper and Mangrove Jack. These fish live up to 40 years of age, weigh up to five to ten kilograms and are highly valued for commercial marketing. The fisheries operate in tropical offshore waters across northern Australia from the Kimberley coast to the Gulf of Carpentaria. The fisheries are primarily commercial using demersal trawl, trap and line fishing gear. The fisheries have a long and varied history of foreign and domestic exploitation. Indicative foreign harvests were two to five kilotonnes per year up to 1990. After 1990, foreign vessel permits were removed and domestic fishing expanded landing in the order of two to three kilotonnes of tropical snappers annually.

In 2007, NAFC listed tropical snapper research as a priority. Past assessments and management settings required revision. New monitoring data on snapper abundance and age composition were needed for assessment of stock status and contemporary management procedures. In response, northern fisheries jurisdictions and the FRDC commissioned tactical research to develop a survey / observer structured fishery monitoring program and critically evaluate the potential use of data. A total of 39 data sets and a range of analyses were used in this process.

Statistical analyses of commercial fishery catch rates quantified variances to establish abundance indicators from structured monitoring. The variances were used to calculate the number of survey / observer days required to monitor tropical snapper catch rates (e.g., standardised number of fish caught per unit area swept by trawling). This result was required to ensure accurate monitoring of catch rates and fish ages so the data were directly aligned for estimation of fishing mortality or, possibly, biomass.

Keywords: Age frequencies, Catch curves, Catch rate standardisation, Fishery management, Lutjanidae, Monitoring, Population modelling, Simulation, Tropical snapper.

Australia’s tropical snapper fisheries harvest six main Lutjanid species. They are the Crimson, Saddletail, and Goldband snappers, Red Emperor, Golden snapper and Mangrove Jack. These fish live up to 40 years of age, weigh up to five to ten kilograms and are highly valued for commercial marketing. The fisheries operate in tropical offshore waters across northern Australia from the Kimberley coast to the Gulf of Carpentaria. The fisheries are primarily commercial using demersal trawl, trap and line fishing gear. The fisheries have a long and varied history of foreign and domestic exploitation. Indicative foreign harvests were two to five kilotonnes per year up to 1990. After 1990, foreign vessel permits were removed and domestic fishing expanded landing in the order of two to three kilotonnes of tropical snappers annually.

In 2007, NAFC listed tropical snapper research as a priority. Past assessments and management settings required revision. New monitoring data on snapper abundance and age composition were needed for assessment of stock status and contemporary management procedures. In response, northern fisheries jurisdictions and the FRDC commissioned tactical research to develop a survey / observer structured fishery monitoring program and critically evaluate the potential use of data. A total of 39 data sets and a range of analyses were used in this process.

Statistical analyses of commercial fishery catch rates quantified variances to establish abundance indicators from structured monitoring. The variances were used to calculate the number of survey / observer days required to monitor tropical snapper catch rates (e.g., standardised number of fish caught per unit area swept by trawling). This result was required to ensure accurate monitoring of catch rates and fish ages so the data were directly aligned for estimation of fishing mortality or, possibly, biomass.

Keywords: Age frequencies, Catch curves, Catch rate standardisation, Fishery management, Lutjanidae, Monitoring, Population modelling, Simulation, Tropical snapper.

Australia’s tropical snapper fisheries harvest six main Lutjanid species. They are the Crimson, Saddletail, and Goldband snappers, Red Emperor, Golden snapper and Mangrove Jack. These fish live up to 40 years of age, weigh up to five to ten kilograms and are highly valued for commercial marketing. The fisheries operate in tropical offshore waters across northern Australia from the Kimberley coast to the Gulf of Carpentaria. The fisheries are primarily commercial using demersal trawl, trap and line fishing gear. The fisheries have a long and varied history of foreign and domestic exploitation. Indicative foreign harvests were two to five kilotonnes per year up to 1990. After 1990, foreign vessel permits were removed and domestic fishing expanded landing in the order of two to three kilotonnes of tropical snappers annually.

In 2007, NAFC listed tropical snapper research as a priority. Past assessments and management settings required revision. New monitoring data on snapper abundance and age composition were needed for assessment of stock status and contemporary management procedures. In response, northern fisheries jurisdictions and the FRDC commissioned tactical research to develop a survey / observer structured fishery monitoring program and critically evaluate the potential use of data. A total of 39 data sets and a range of analyses were used in this process.

Statistical analyses of commercial fishery catch rates quantified variances to establish abundance indicators from structured monitoring. The variances were used to calculate the number of survey / observer days required to monitor tropical snapper catch rates (e.g., standardised number of fish caught per unit area swept by trawling). This result was required to ensure accurate monitoring of catch rates and fish ages so the data were directly aligned for estimation of fishing mortality or, possibly, biomass.

Keywords: Age frequencies, Catch curves, Catch rate standardisation, Fishery management, Lutjanidae, Monitoring, Population modelling, Simulation, Tropical snapper.

Australia’s tropical snapper fisheries harvest six main Lutjanid species. They are the Crimson, Saddletail, and Goldband snappers, Red Emperor, Golden snapper and Mangrove Jack. These fish live up to 40 years of age, weigh up to five to ten kilograms and are highly valued for commercial marketing. The fisheries operate in tropical offshore waters across northern Australia from the Kimberley coast to the Gulf of Carpentaria. The fisheries are primarily commercial using demersal trawl, trap and line fishing gear. The fisheries have a long and varied history of foreign and domestic exploitation. Indicative foreign harvests were two to five kilotonnes per year up to 1990. After 1990, foreign vessel permits were removed and domestic fishing expanded landing in the order of two to three kilotonnes of tropical snappers annually.

In 2007, NAFC listed tropical snapper research as a priority. Past assessments and management settings required revision. New monitoring data on snapper abundance and age composition were needed for assessment of stock status and contemporary management procedures. In response, northern fisheries jurisdictions and the FRDC commissioned tactical research to develop a survey / observer structured fishery monitoring program and critically evaluate the potential use of data. A total of 39 data sets and a range of analyses were used in this process.

Statistical analyses of commercial fishery catch rates quantified variances to establish abundance indicators from structured monitoring. The variances were used to calculate the number of survey / observer days required to monitor tropical snapper catch rates (e.g., standardised number of fish caught per unit area swept by trawling). This result was required to ensure accurate monitoring of catch rates and fish ages so the data were directly aligned for estimation of fishing mortality or, possibly, biomass.

Keywords: Age frequencies, Catch curves, Catch rate standardisation, Fishery management, Lutjanidae, Monitoring, Population modelling, Simulation, Tropical snapper.

Australia’s tropical snapper fisheries harvest six main Lutjanid species. They are the Crimson, Saddletail, and Goldband snappers, Red Emperor, Golden snapper and Mangrove Jack. These fish live up to 40 years of age, weigh up to five to ten kilograms and are highly valued for commercial marketing. The fisheries operate in tropical offshore waters across northern Australia from the Kimberley coast to the Gulf of Carpentaria. The fisheries are primarily commercial using demersal trawl, trap and line fishing gear. The fisheries have a long and varied history of foreign and domestic exploitation. Indicative foreign harvests were two to five kilotonnes per year up to 1990. After 1990, foreign vessel permits were removed and domestic fishing expanded landing in the order of two to three kilotonnes of tropical snappers annually.

In 2007, NAFC listed tropical snapper research as a priority. Past assessments and management settings required revision. New monitoring data on snapper abundance and age composition were needed for assessment of stock status and contemporary management procedures. In response, northern fisheries jurisdictions and the FRDC commissioned tactical research to develop a survey / observer structured fishery monitoring program and critically evaluate the potential use of data. A total of 39 data sets and a range of analyses were used in this process.

Statistical analyses of commercial fishery catch rates quantified variances to establish abundance indicators from structured monitoring. The variances were used to calculate the number of survey / observer days required to monitor tropical snapper catch rates (e.g., standardised number of fish caught per unit area swept by trawling). This result was required to ensure accurate monitoring of catch rates and fish ages so the data were directly aligned for estimation of fishing mortality or, possibly, biomass.

Keywords: Age frequencies, Catch curves, Catch rate standardisation, Fishery management, Lutjanidae, Monitoring, Population modelling, Simulation, Tropical snapper.

Australia’s tropical snapper fisheries harvest six main Lutjanid species. They are the Crimson, Saddletail, and Goldband snappers, Red Emperor, Golden snapper and Mangrove Jack. These fish live up to 40 years of age, weigh up to five to ten kilograms and are highly valued for commercial marketing. The fisheries operate in tropical offshore waters across northern Australia from the Kimberley coast to the Gulf of Carpentaria. The fisheries are primarily commercial using demersal trawl, trap and line fishing gear. The fisheries have a long and varied history of foreign and domestic exploitation. Indicative foreign harvests were two to five kilotonnes per year up to 1990. After 1990, foreign vessel permits were removed and domestic fishing expanded landing in the order of two to three kilotonnes of tropical snappers annually.

In 2007, NAFC listed tropical snapper research as a priority. Past assessments and management settings required revision. New monitoring data on snapper abundance and age composition were needed for assessment of stock status and contemporary management procedures. In response, northern fisheries jurisdictions and the FRDC commissioned tactical research to develop a survey / observer structured fishery monitoring program and critically evaluate the potential use of data. A total of 39 data sets and a range of analyses were used in this process.

Statistical analyses of commercial fishery catch rates quantified variances to establish abundance indicators from structured monitoring. The variances were used to calculate the number of survey / observer days required to monitor tropical snapper catch rates (e.g., standardised number of fish caught per unit area swept by trawling). This result was required to ensure accurate monitoring of catch rates and fish ages so the data were directly aligned for estimation of fishing mortality or, possibly, biomass.

Keywords: Age frequencies, Catch curves, Catch rate standardisation, Fishery management, Lutjanidae, Monitoring, Population modelling, Simulation, Tropical snapper.

It is now widely recognized that fisheries can have impacts on marine species, habitats and ecosystems beyond the direct impacts of fishing on target species. For example, hundreds of species are regularly caught and discarded in many trawl and longline fisheries and in particular, interactions with threatened species are a concern in many fisheries. Impacts on habitats and ecological communities as a result of fishing activities have also been documented. To address these broader impacts of fishing, ecosystem-based fisheries management (EBFM) has emerged as a complementary approach to single-species management. Development of practical methods to implement EBFM has generally lagged the policy mandates, and so development of scientific and management tools to support practical implementation has been critical.

Moves towards EBFM have also evolved in Australian fisheries during the past decade, driven by a number of policy directions and initiatives. These include: (i) a national approach to ecologically sustainable development; (ii) development of fisheries legislation that incorporates explicit reference to wider ecological impacts of fishing (e.g. the Fisheries Management Act 1991); (iii) new environmental legislation that assesses fisheries against environmental standards (e.g. the Environmental Protection and Biodiversity Conservation Act 1999); and (iv) Australia’s Oceans Policy, which also adopts an explicit ecosystem-based approach to management.

It is now widely recognized that fisheries can have impacts on marine species, habitats and ecosystems beyond the direct impacts of fishing on target species. For example, hundreds of species are regularly caught and discarded in many trawl and longline fisheries and in particular, interactions with threatened species are a concern in many fisheries. Impacts on habitats and ecological communities as a result of fishing activities have also been documented. To address these broader impacts of fishing, ecosystem-based fisheries management (EBFM) has emerged as a complementary approach to single-species management. Development of practical methods to implement EBFM has generally lagged the policy mandates, and so development of scientific and management tools to support practical implementation has been critical.

Moves towards EBFM have also evolved in Australian fisheries during the past decade, driven by a number of policy directions and initiatives. These include: (i) a national approach to ecologically sustainable development; (ii) development of fisheries legislation that incorporates explicit reference to wider ecological impacts of fishing (e.g. the Fisheries Management Act 1991); (iii) new environmental legislation that assesses fisheries against environmental standards (e.g. the Environmental Protection and Biodiversity Conservation Act 1999); and (iv) Australia’s Oceans Policy, which also adopts an explicit ecosystem-based approach to management.

It is now widely recognized that fisheries can have impacts on marine species, habitats and ecosystems beyond the direct impacts of fishing on target species. For example, hundreds of species are regularly caught and discarded in many trawl and longline fisheries and in particular, interactions with threatened species are a concern in many fisheries. Impacts on habitats and ecological communities as a result of fishing activities have also been documented. To address these broader impacts of fishing, ecosystem-based fisheries management (EBFM) has emerged as a complementary approach to single-species management. Development of practical methods to implement EBFM has generally lagged the policy mandates, and so development of scientific and management tools to support practical implementation has been critical.

Moves towards EBFM have also evolved in Australian fisheries during the past decade, driven by a number of policy directions and initiatives. These include: (i) a national approach to ecologically sustainable development; (ii) development of fisheries legislation that incorporates explicit reference to wider ecological impacts of fishing (e.g. the Fisheries Management Act 1991); (iii) new environmental legislation that assesses fisheries against environmental standards (e.g. the Environmental Protection and Biodiversity Conservation Act 1999); and (iv) Australia’s Oceans Policy, which also adopts an explicit ecosystem-based approach to management.

It is now widely recognized that fisheries can have impacts on marine species, habitats and ecosystems beyond the direct impacts of fishing on target species. For example, hundreds of species are regularly caught and discarded in many trawl and longline fisheries and in particular, interactions with threatened species are a concern in many fisheries. Impacts on habitats and ecological communities as a result of fishing activities have also been documented. To address these broader impacts of fishing, ecosystem-based fisheries management (EBFM) has emerged as a complementary approach to single-species management. Development of practical methods to implement EBFM has generally lagged the policy mandates, and so development of scientific and management tools to support practical implementation has been critical.

Moves towards EBFM have also evolved in Australian fisheries during the past decade, driven by a number of policy directions and initiatives. These include: (i) a national approach to ecologically sustainable development; (ii) development of fisheries legislation that incorporates explicit reference to wider ecological impacts of fishing (e.g. the Fisheries Management Act 1991); (iii) new environmental legislation that assesses fisheries against environmental standards (e.g. the Environmental Protection and Biodiversity Conservation Act 1999); and (iv) Australia’s Oceans Policy, which also adopts an explicit ecosystem-based approach to management.

It is now widely recognized that fisheries can have impacts on marine species, habitats and ecosystems beyond the direct impacts of fishing on target species. For example, hundreds of species are regularly caught and discarded in many trawl and longline fisheries and in particular, interactions with threatened species are a concern in many fisheries. Impacts on habitats and ecological communities as a result of fishing activities have also been documented. To address these broader impacts of fishing, ecosystem-based fisheries management (EBFM) has emerged as a complementary approach to single-species management. Development of practical methods to implement EBFM has generally lagged the policy mandates, and so development of scientific and management tools to support practical implementation has been critical.

Moves towards EBFM have also evolved in Australian fisheries during the past decade, driven by a number of policy directions and initiatives. These include: (i) a national approach to ecologically sustainable development; (ii) development of fisheries legislation that incorporates explicit reference to wider ecological impacts of fishing (e.g. the Fisheries Management Act 1991); (iii) new environmental legislation that assesses fisheries against environmental standards (e.g. the Environmental Protection and Biodiversity Conservation Act 1999); and (iv) Australia’s Oceans Policy, which also adopts an explicit ecosystem-based approach to management.

It is now widely recognized that fisheries can have impacts on marine species, habitats and ecosystems beyond the direct impacts of fishing on target species. For example, hundreds of species are regularly caught and discarded in many trawl and longline fisheries and in particular, interactions with threatened species are a concern in many fisheries. Impacts on habitats and ecological communities as a result of fishing activities have also been documented. To address these broader impacts of fishing, ecosystem-based fisheries management (EBFM) has emerged as a complementary approach to single-species management. Development of practical methods to implement EBFM has generally lagged the policy mandates, and so development of scientific and management tools to support practical implementation has been critical.

Moves towards EBFM have also evolved in Australian fisheries during the past decade, driven by a number of policy directions and initiatives. These include: (i) a national approach to ecologically sustainable development; (ii) development of fisheries legislation that incorporates explicit reference to wider ecological impacts of fishing (e.g. the Fisheries Management Act 1991); (iii) new environmental legislation that assesses fisheries against environmental standards (e.g. the Environmental Protection and Biodiversity Conservation Act 1999); and (iv) Australia’s Oceans Policy, which also adopts an explicit ecosystem-based approach to management.

It is now widely recognized that fisheries can have impacts on marine species, habitats and ecosystems beyond the direct impacts of fishing on target species. For example, hundreds of species are regularly caught and discarded in many trawl and longline fisheries and in particular, interactions with threatened species are a concern in many fisheries. Impacts on habitats and ecological communities as a result of fishing activities have also been documented. To address these broader impacts of fishing, ecosystem-based fisheries management (EBFM) has emerged as a complementary approach to single-species management. Development of practical methods to implement EBFM has generally lagged the policy mandates, and so development of scientific and management tools to support practical implementation has been critical.

Moves towards EBFM have also evolved in Australian fisheries during the past decade, driven by a number of policy directions and initiatives. These include: (i) a national approach to ecologically sustainable development; (ii) development of fisheries legislation that incorporates explicit reference to wider ecological impacts of fishing (e.g. the Fisheries Management Act 1991); (iii) new environmental legislation that assesses fisheries against environmental standards (e.g. the Environmental Protection and Biodiversity Conservation Act 1999); and (iv) Australia’s Oceans Policy, which also adopts an explicit ecosystem-based approach to management.

It is now widely recognized that fisheries can have impacts on marine species, habitats and ecosystems beyond the direct impacts of fishing on target species. For example, hundreds of species are regularly caught and discarded in many trawl and longline fisheries and in particular, interactions with threatened species are a concern in many fisheries. Impacts on habitats and ecological communities as a result of fishing activities have also been documented. To address these broader impacts of fishing, ecosystem-based fisheries management (EBFM) has emerged as a complementary approach to single-species management. Development of practical methods to implement EBFM has generally lagged the policy mandates, and so development of scientific and management tools to support practical implementation has been critical.

Moves towards EBFM have also evolved in Australian fisheries during the past decade, driven by a number of policy directions and initiatives. These include: (i) a national approach to ecologically sustainable development; (ii) development of fisheries legislation that incorporates explicit reference to wider ecological impacts of fishing (e.g. the Fisheries Management Act 1991); (iii) new environmental legislation that assesses fisheries against environmental standards (e.g. the Environmental Protection and Biodiversity Conservation Act 1999); and (iv) Australia’s Oceans Policy, which also adopts an explicit ecosystem-based approach to management.

It is now widely recognized that fisheries can have impacts on marine species, habitats and ecosystems beyond the direct impacts of fishing on target species. For example, hundreds of species are regularly caught and discarded in many trawl and longline fisheries and in particular, interactions with threatened species are a concern in many fisheries. Impacts on habitats and ecological communities as a result of fishing activities have also been documented. To address these broader impacts of fishing, ecosystem-based fisheries management (EBFM) has emerged as a complementary approach to single-species management. Development of practical methods to implement EBFM has generally lagged the policy mandates, and so development of scientific and management tools to support practical implementation has been critical.

Moves towards EBFM have also evolved in Australian fisheries during the past decade, driven by a number of policy directions and initiatives. These include: (i) a national approach to ecologically sustainable development; (ii) development of fisheries legislation that incorporates explicit reference to wider ecological impacts of fishing (e.g. the Fisheries Management Act 1991); (iii) new environmental legislation that assesses fisheries against environmental standards (e.g. the Environmental Protection and Biodiversity Conservation Act 1999); and (iv) Australia’s Oceans Policy, which also adopts an explicit ecosystem-based approach to management.