PROJECT NUMBER
•
1999-150
PROJECT STATUS:
COMPLETED
ORGANISATION:
Department of Primary Industries and Regional Development (DPIRD) WA
SPECIES
4,221 results
Determination of patagonian toothfish age, growth and population characteristics based on otoliths
Project number:
1997-123
Project Status:
Completed
Budget expenditure:
$22,850.00
Principal Investigator:
John Kalish
Organisation:
Australian National University (ANU)
Project start/end date:
29 Jun 1997
-
2 May 2001
Contact:
FRDC
Data on fish age are essential to determine the production of fish stocks. Collection of age structure data early in the history of a fishery are particularly important to determine the natural mortality rate of a population. Data relating to the age structure of populations and growth rates can also be applied to the identification of stocks. Annual estimates of population age structure are employed to identify population responses to exploitation and environmental variability and can be used to develop more data intensive methods of population assessment (eg Virtual Population Analysis). Otoliths are the structures employed most often to estimate age of fishes and validation research at the ANU indicates that toothfish otoliths are suitable for this purpose.
A "stock" is the basic unit of management in most fisheries and identification of these units is a prerequisite to accurate assessment and effective management. There are no data on stock structure for Patagonian toothfish. As a result, we have no knowledge regarding the potential impacts of toothfish exploitation outside the AFZ on toothfish stocks within the AFZ.
Knowledge of toothfish biology is extremely limited. Given the lack of baseline biological data, it would be difficult to identify possible responses of toothfish stocks to exploitation or differences in life history characteristics among putative stocks. Identification of changes in basic life history characteristics such as age or size at maturity and timing of ontogenetic migrations are important to management of fish species within both a stock and ecosystem context.
1. Validate otolith-based age estimates for Patagonian toothfish (Dissostichus eleginoides).
2. Establish routine age estimation procedures for Patagonian toothfish.
3. Determine growth rates for Patagonian toothfish.
4. Determine age structure of the toothfish populations from the AFZ surrounding Macquarie Island and other localities
5. Determine age structure from successive years of sampling to identify possible shifts in age structure or inconsistencies in the application of the age estimation method.
6. Liaise with groups involved with modelling the dynamics of toothfish populations.
7. Apply otolith morphometrics and otolith chemistry to discrimination of possible toothfish stocks.
8. Establish an inter-agency (international) program to determine if there is variation in the interpretation of toothfish otolith sections
9. Publish reports for immediate stock assessment and management purposes and peer-reviewed articles in international journals for dissemination of results.
Final report
Assessment of seal fishery interactions in the South East Trawl Fishery (SETF) and the development of fishing practices and seal exclusion devices (SEDs) in the winter blue grenadier fishery to mitigate seal bycatch by SETF trawlers
Project number:
2001-008
Project Status:
Completed
Budget expenditure:
$287,245.00
Principal Investigator:
Richard Tilzey
Organisation:
Department of Agriculture, Fisheries and Forestry (DAFF) ABARES
Project start/end date:
30 Jan 2001
-
30 Jun 2005
Contact:
FRDC
With the continuing recovery in the size of Australian-based fur seal populations post-sealing, a corresponding increase in seal interactions with domestic fishing vessels is occurring and will continue. There is an urgent need to develop effective seal bycatch prevention procedures to prevent fishing operations from being severely curtailed, or closed down, under the Environment Protection and Biodiversity Conservation Act 1999.
Following the 1999 winter blue grenadier season, incidental seal mortalities emerged as a major issue that threatened the continuation of this fishery; at least that part of the fishery harvested by factory trawlers. These trawlers had successfully developed the fishery, increasing the total grenadier catch from about 3000 t in 1996 to over 9000 t in 1999. The processed value of the factory trawler catch is now around $20 million per year (ASIC 2003) at first sale. The seal deaths in 1999 resulted in significant pressure from some environmental groups to prevent factory trawlers access to this fishery in 2000. This action would have caused significant loss of income in this sector and possibly jeopardised the future participation of factory trawlers in the fishery. There is a strong need for such vessels to demonstrate that seal bycatch can be reduced by adopting appropriate fishing procedures and gears.
It is also likely that pressures will be brought to bear on the ‘wet boats’ fishing for blue grenadier and possibly the rest of the SEF trawl fleet to take measures to reduce incidental seal captures. The study by Knuckey et al. (2002) indicated seal bycatch to occur virtually across the whole multi-species trawl fishery. Some of the results of the development and testing of SEDs and other mitigation measures by the factory trawlers in the targeted ‘single-species’ fishery under this project may be transferable to other vessel operators in the wider multi-species fishery, helping them to avoid many potential operational problems and costs. Increasing the effectiveness of SEDs in both reducing seal mortalities and minimising fish losses would be an important step in helping to gain wider industry acceptance of the potential use of these devices.
1. To improve the effectiveness of Seal Exclusion Devices (SEDs) in blue grenadier trawl nets in reducing seal mortalities and minimising losses of fish.
2. To assess the effectiveness of fishing techniques aimed at minimising seal bycatch.
3. To gather full biological information from all seal fatalities.
4. To achieve full observer coverage of freezer-trawler activities during the 2001 and 2002 winter grenadier fishery and monitor seal numbers around vessels and all seal-trawl interactions.
5. To gather information on seal movements/residence time in the winter grenadier fishery.
Final report
ISBN:
978-1-925983-05-0
Author:
Richard Tilzey
Final Report
•
2007-04-30
•
2.06 MB
2001-008-DLD.pdf
Introducing a Code of Fishing Practice aimed at avoiding seals appeared to halve the incidence of seal bycatch in this fishery. In SED trials, the problems of fish-loss via the SED escape hatch and net blockage via the SED grid were solved by changes in SED design. Although the effectiveness of most SED designs in reducing seal bycatch could not be quantified, the forward facing, ‘top-hatch’ SED design used in 2002 significantly lowered the incidence of seal bycatch in midwater trawl nets. Trials with this design are continuing. Some of the major factors that influence the probability of seal bycatch occurring in this fishery were delineated. Biological sampling of seal fatalities showed the dominant seal bycatch to be sub-adult male Australian fur seals habituated to foraging from trawl nets. Seal tracking studies developed a novel method of tagging seals at sea and indicated that a comparatively small and intransient sub-set of their population interacted with this fishery.
The following recommendations were made in the winter grenadier fishery: use open, forward-facing, ‘top-hatch’ SEDs (or a more effective design if one is developed) in all midwater net shots (or as directed for research purposes); continue the Code of Fishing Practice; continue the shot-by-shot recording of seal bycatch in the SEF1 logbook and maintain a level of scientific observer coverage and biological data collection; and, continue trials of the ‘top-hatch’ SED and gather more information by using underwater filming on the timing and depth–frequency of net entry by seals, and the circumstances of net entry that place seals at risk.
The following recommendations were made in the rest of the SEF trawl fleet: Priority should be given to assessing the nature and extent of seal-fishery activities across the fishery; The Code of Fishing Practice should be followed where practicable; and, At this juncture, SED use should be confined to large midwater trawl nets in areas where seals are known to be common, as more assessment of SED effectiveness is needed before extending their usage.
Project results also assisted the goal of obtaining accreditation for the SEF under a Section 33 determination under this Act.
Keywords: Blue grenadier trawl fishery, seal bycatch mitigation, Seal Exclusion Devices, Australian fur seal biology.
Project products
PROJECT NUMBER
•
1999-112
PROJECT STATUS:
COMPLETED
ORGANISATION:
University of Tasmania (UTAS)
SPECIES
PROJECT NUMBER
•
2016-406
PROJECT STATUS:
COMPLETED
Australian Society for Fish Biology: Scientific networking, early career development and international engagement
The 2019 ASFB conference was held in Canberra from 14 to 17 October, 2019 at the National Library of Australia, ACT. The conference theme of “Communicate to illuminate & inspire" encouraged the 251 delegates (including 62 students) from across Australia, New Zealand, Europe, South Africa,...
ORGANISATION:
Australian Society For Fish Biology Inc
PROJECT NUMBER
•
2003-045
PROJECT STATUS:
COMPLETED
Stock discrimination of blue-eye trevalla (Hyperglyphe antarctica) from Australian shelf waters and offshore seamounts and New Zealand
This work is principally about identifying the best method for examining the population structure of blue-eye trevalla (Hyperoglyphe antarctica). It is not, and was never intended to be, an exhaustive assessment of stock structure of blue-eye trevalla in Australia’s Fishing Zone. As such,...
ORGANISATION:
Agriculture Victoria
SPECIES
PROJECT NUMBER
•
1992-040
PROJECT STATUS:
COMPLETED
Investigation of methods to age abalone
Management of the valuable Australian abalone fishery is difficult because catch/effort information for abalone does not provide warnings of declining stocks. In fact abalone fisheries in Alaska, California and Mexico have collapsed or declined dramatically, with little warning. Management must rely...
ORGANISATION:
University of Melbourne
PROJECT NUMBER
•
2010-738
PROJECT STATUS:
COMPLETED
SCRC: Reducing inflammation in the elderly with a high seafood diet
With ageing, the inflammatory process is aggravated and it is becoming increasingly recognised that chronic, low-grade inflammation is associated with increased risk for cardiovascular, and a number of other, chronic diseases. The role of nutrition in the development and resolution of inflammation...
ORGANISATION:
Flinders University
PROJECT NUMBER
•
1997-111
PROJECT STATUS:
COMPLETED
Catch-at-age, age at first spawning, historical changes in growth, and natural mortality of SBT: an integrated study of key uncertainties in population biology and dynamics of SBT, based on direct estimates of age from otoliths
The CCSBT has recognized for a number of years that a better understanding of the population biology and demographics of southern bluefin tuna (SBT) is necessary for improved population modeling and stock assessments. In 1996, the CCSBT Scientific Committee identified three areas where our...
ORGANISATION:
CSIRO Oceans and Atmosphere Hobart
SPECIES
PROJECT NUMBER
•
2008-314.14
PROJECT STATUS:
COMPLETED
ORGANISATION:
Murdoch University
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