Estimation of snapper year class strength in SNA 2
Project: Estimation of snapper year class strength in SNA 2
Project Code: SNA2004/04
Start Date: 1 October 2004
Completion Date: 31 May 2006
Vessel Use: None
Overall Objectives:
- To estimate the year class strengths of snapper (Pagrus auratus) in SNA 2.
Specific Objectives:
- To carry out sampling and estimate the relative proportion at age and length of recruited snapper sampled from the commercial catch in SNA 2 during 2004/05. The target coefficient of variation (c.v.) for the catch at age will be 20 % (mean weighted c.v. across all age classes).
Note:
The duration of this project will be 20 months, 1 October 2004 to 31 May 2006. This will allow the successful tenderer time to sample the fishery for 12 months and present the results to the Fishery Assessment Working Group meetings in 2006.
Rationale:
General
The snapper fishery is New Zealand’s largest inshore finfish fishery by value. SNA 2 is a small stock, but is regionally important, with a current TACC of 315 t. The TAC for this stock was increased in 2002 to 450 t with allowances for customary Maori (14 t), recreational fishing (90 t), and other sources of mortality attributable to fishing (31 t). Estimates of catch from the last recreational survey in this area were much higher than the current allowance but are considered to be unreliable.
The fishery has been monitored in recent years by catch at age sampling. In the absence of any abundance indices the stock assessment model uses the catch at age data to determine mortality in the stock.
Objective 1
The aim of shed sampling is to estimate the age and length structure of the commercial landings of snapper. These data are required to determine estimates of relative year class strength in the population models used to assess the status of SNA 2. Shed sampling was last carried out in SNA 2 in 2002-03.
The Snapper Research Planning Group suggested that sampling every 3 years would provide an indication of recruitment patterns in the stock to allow stock status to be monitored. It is proposed here to carry out the sampling one year earlier to allow the stock assessment to be updated in 2006.
Strategic Relevance
All the objectives in this project are consistent with 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:
• SNA 2
The project is estimated to cost between $50,000 — $100,000.