Stock assessment of tarakihi in TAR 7

Project: Stock assessment of tarakihi in TAR 7
Project Code: TAR2004/01
Start Date: 1 October 2004
Completion Date: 28 February 2008
Vessel Use: Nil

Overall Objectives:

1. To develop a stock assessment model for Tarakihi (Nemadactylus macropterus) in TAR 7

Specific Objectives:

1. To conduct sampling in fish processing sheds and determine the length and age structure of the commercial catch of tarakihi in TAR 7. Annual target coefficients of variation (c.v.) for the catch at age is 30% (mean weighted c.v. across all age classes).
2. To age tarakihi otoliths collected from the 2005 trawl survey.
3. To carry out a stock assessment of this fishery, including estimating biomass and sustainable yields.

Rationale:

General

Tarakihi is one of the most important inshore commercial fish species (6119 t in 2001–02), and is a major recreational target species. Catches in TAR 7 have remained stable at about 900–1100 t, just under the level of the TACC, over the past 8 years. However, recent trawl surveys have suggested a decline of about 30% over the same period. The 2003 WCSI trawl survey also indicated some recent weak year classes for the TAR 7 stock.

Objective 1

A commercial catch sampling programme is proposed which would supplement the otoliths collected during the TAR 7 trawl surveys. This would provide estimates of commercial catch composition and trawl selectivity. The proposed research would be cost-effective as tarakihi could be added to the existing catch sampling programme for john dory, gurnard and snapper. A three year shed sampling programme is proposed.

Objective 2

Otoliths for the earlier surveys have already been read.

Objective 3

Stock assessment results, available by 25 March 2006, will be based on surveys conducted up to April 2005 and on a selectivity function derived from one years shed sampling. Shed sampling will continue for an additional two years to allow for a better estimation of selectivity for future assessments. If the full three years of commercial catch sampling for TAR 7 reveals that the selectivity function based in the first year’s samples is inaccurate, a revision of the stock assessment will be necessary.

Strategic Relevance

The objective of this project is consistent with Strategic Objectives iii and v of the Fisheries Resources goal in 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:

• TAR 7

The project is estimated to cost between $150,000-$200,000.