Biomass estimation for snapper in SNA 1

Project: Biomass estimation for snapper in SNA 1
Project Code: SNA2004/05
Start Date: 1 October 2004
Completion Date: 31 December 2007
Vessel Use: None

Overall Objectives:

1. To estimate biomass of snapper (Pagrus auratus) in SNA 1.

Specific Objectives:

1. To carry out a mark-recapture programme in order to estimate the absolute biomass of snapper in SNA 1 and the selectivity of the main fishing methods used in the SNA 1 fishery.

Rationale

General

The snapper fishery is New Zealand’s largest inshore finfish fishery by value. SNA 1 is the largest snapper fishery with a current TACC of 4500 t out of the total snapper TACC for all areas combined of 6494 t. Snapper also form important fisheries for recreational fishers and Maori, but the annual catch is not known reliably.

Biomass estimates are important components of the stock assessment modelling of this fishery. The model requires absolute biomass estimates at intervals of about 5 years. Between absolute biomass estimates, stock age composition is monitored by market sampling and the catch-atage data is fundamental to the age-structured models for estimating and validating annual recruitment and hence biomass. The last estimate of absolute biomass for SNA 1 was determined from a mark-recapture programme during 1993/94.

Objective 1

The design of the next tagging programme will be determined in the research project SNA2003/05. Improved estimates of selectivity are also required for SNA 1 and the markrecapture programme design will provide for these estimates. It is proposed that the tag release phase is completed in the spring-summer of 2005-06 with preliminary results available in 2007.

Strategic Relevance

All the objectives in this project are consistent with the Fisheries Resources goal in the Ministry of Fisheries Strategic Research Directions document.

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:

• SNA 1

The project is estimated to cost between more than $1.5 million.