Stock assessment of TRE 7
Project: Stock assessment of TRE 7
Project Code: TRE2004/02
Start Date: 1 October 2004
Completion Date: 30 September 2005
Vessel Use: None
Overall Objectives:
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To conduct a stock assessment for trevally (Pseudocaranx dentex) in TRE 7, including estimating biomass and sustainable yields
Specific Objectives:
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To update the descriptive analysis of the TRE 7 fishery up to the end of the 2003/04 fishing year.
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To analyse age and length frequency data for trevally collected by the shed sampling programme up to the 2003/04 fishing year for input into a stock assessment model.
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To review and summarise the historical biological data (including length frequency, sex ratio, otoliths, and reproductive condition data) for trevally collected from the shed sampling programme and other sources and the use of these data as inputs into a stock assessment.
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To update the standardised CPUE indices for TRE 7 up to the end of the 2003/04 fishing year.
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To conduct a stock assessment, including estimating biomass and sustainable yields for TRE 7.
Note:
The specific objectives for this project may be modified after the Pelagic Fisheries Stock Assessment Working Group reviews the outputs of some current into the sensitivity of the current assessment to M and improvements to the standardised CPUE index.
Rationale:
General
What is the current stock status of trevally in TRE 7? The most recent assessment of the TRE 7 stock was reported in early 2003 and was of concern to fishery managers. The Pelagic Fisheries Stock Assessment Working Group recommended improvements to the assessment approach, which are currently underway. Additional catch and effort data will be available with which to update the assessment in 2004/05.
Trevally is caught around the North Island and the north of the South Island. Combined commercial landings totalled 3,179 t in 2001/2002, with a landed value around $ 3 million. The largest fisheries in 2001/2002 were in TRE 7 (1,852 t) and TRE 1 (1,086 t). In the southern coastal mixed trawl fishery, trevally is taken mostly in targets tows and in conjunction with snapper. Trevally is popular with recreational fishers with annual recreational catches estimated to be about 75 t in TRE 7.
Objective 1
Project TRE2000/02 undertook a stock assessment for TRE 7. Subsequent to that assessment, further research was recommended on CPUE standardisation and the sensitivity of the model to M (including consideration of an age-specific mortality structuring of the model). That research is currently underway.
The outputs of that research and additional input data (additional years in the CPUE indices, additional catch data and additional catch sampling data) will be available by late 2004. This project will use the existing assessment approach to revise and update the TRE 7 stock assessment. Additional issues to be considered in the revised assessment as discussed by the PELWG include modification of the likelihood to reflect the data collection methods, consideration of annual variation in growth and/or selectivity, increase the plus group, incorporation of a prior for BO and the provision of more advanced diagnostics.
The project should also include an analysis of best approaches for future data collection, in particular optimisation of any shed sampling programme.
Strategic Relevance
This project forms a part of the programme to provide the information on sustainable yields and stock status required for the sustainable utilisation of New Zealand’s fisheries resources, a part of the trevally medium-term research plan and a part of the pelagic fisheries medium term research plan. This project is consistent with the Ministry of Fisheries Strategic Research Directions document.
Cost Recovery Information:
The percentage allocation for this project will be attributed to the following Fishstock according to rule 9.1 of the Fisheries (Cost Recovery) Rules 2001:
The project is estimated to cost between $50,000 - $100,000.