Fisheries Infosite

Plenary (COC1A_FINAL 08)

COC1A_FINAL 08.pdf

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COC1A_FINAL 08.pdf (198.1 kb)



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. There has been a

large increase (78%) in recruited biomass on Snake Bank since the last survey in 2006, but the 2007

length frequency distribution suggests that the recruitment of juveniles (under 20 mm SL) has been

poor compared with recent years, and this could lead to reduced levels of adult recruitment to the

fishery over the next year or two. 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 lower than the estimated CAY (414 t) unless a large size (35

mm SL) at recruitment is assumed, suggesting that fishing at the level of the current TACC is likely to

be sustainable in the short term. Current reported landings (137 t) are less than both the TACC and the

estimated CAY. Annual surveys are being used to monitor the stock closely, but it is not known if

current catch limits will allow the stock to move towards a size that will support the MSY.

Document date
Thursday, 15 May 2008
Document type
V 1.3
File format
Adobe PDF
File size
198.1 kb
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Uploaded date
Friday, 7 November 2008

Search tags
Species: COC;
Stock: COC1A;

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