14_COC1A_09

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14_COC1A_09.pdf

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14_COC1A_09.pdf (172.6 kb)

Abstract
Cockles recruit to the spawning stock on Snake Bank at a size of approximately 18 mm shell length. The Snake Bank cockle population may also receive spat from other beds in the harbour. Therefore, at the current harvest size (about 30 mm shell length) there is probably a low risk of recruitment overfishing the Snake Bank population, even at high levels of fishing pressure. The risk of recruitment overfishing, however, increases as the average size of cockles harvested decreases.

The recruited biomass of cockles (>30 mm shell length) on Snake Bank declined from over 2000 t in the early 1980s to about 700 t in the early 1990s. It has since fluctuated between about 500 and 1500 t without apparent trend, falling to particularly low levels (<500 t) in 2001 and 2002. Recruited biomass in 2009 was considerably lower than that estimated from the last two surveys in 2007 and 2008 (the highest levels since 1999), but similar to that in 2006. The 2009 length frequency distribution suggests there has been a slight increase in the recruitment of juveniles (under 20 mm SL) compared with recent years (2007 and 2008), and this could lead to relatively moderate levels of adult recruitment to the fishery in the near future. Before October 2002 (when COC 1A was introduced to the QMS), the sum of the daily catch limits (584 t), and average landings between 1989–90 and 2001–02 (457 t) both greatly exceeded estimates of MAY (maximum average yield based on the average of CAY estimates over recent years). In October 2002, the commercial catch limit was reduced from 584 t to a TACC of 346 t. This current TACC is higher than the estimated CAY (239 t) unless a smaller size (28 mm SL or shorter) at recruitment is assumed, suggesting that fishing at the level of the current TACC is unlikely to be sustainable in the long term. Current reported landings (151 t) are less than both the TACC and the estimated CAY.

Document date
Sunday, 31 May 2009

Document type
V 1.3

File format
Adobe PDF

File size
172.6 kb

Reference number
2009

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M:\SCIPOL\Working Groups 2009\Plenary 2009\FINAL\MFish 2009 May Plenary\May 2009 - PDF\14_COC1A_09.pdf

Uploaded date
Wednesday, 10 June 2009

Search tags

Species: COC;
Stock: COC1A;

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