Assessment Model
Type: Age-structured
Integrated Catch at Age analysis (ICA)
Methodology
Integrated Catch at age analysis (Patterson and Melvin 1996) uses separable virtual population analysis (VPA) (Pope & Shepherd, 1985) with weighted tuning indices. ICA was applied for the Aegean anchovy tock and it was based on commercial catch data (2000-2006) and tuning indices were the biomass estimates from acoustic surveys and Daily Egg Production Method (DEPM) estimates over the period 2003-2006, that were used as relative indices of abundance.
Overall Assessment Results
This assessment suggestions should be taken as preliminary and cautionary, as this ICA assessment for this area it is based on a short time series of data.The major component of the stock were the 1-year-old and 2-year-old-anchovy (i.e. the recruitment to the fishery). An increasing trend in the number of recruits of age 0 was observed in 2006. Furthermore, TB and SSB estimates showed sharp increase and recovery of the stock. Fishing mortality seems to level out since 2004.
Opposed to the results of a previous preiliminary ICA assessment (GFCM 2007: 4 years of separable constraints and M=1.2) lower levels of exploitation rate have been estimated. Specifically, the highest value of the exploitation rate was estimated in 2003, followed by a decrease well below the empirical level for stock decline (E>0.4, Patterson 1992) for small pelagic in 2004, 2005 and 2006.
Monitoring should be continued on an annual basis and a time series extension is required in order to be able to suggest reliable Reference Points for this fishery. Monitoring of the status of the stock with fisheries independent techniques is essential for this fishery.
Scientific Advice
For management considerationsThe major component of the stock were the 1-year-old and 2-year-old-sardine (i.e. the recruitment to the fishery). The current assessment of ICA for anchovy indicated high levels of exploitation rate but with a decreasing trend since 2003, below the empirical level for stock decline (E<0.4, Patterson 1992) for small pelagic.
Further monitoring of the fishery is required in order to produce reliable and effective Reference Points for the anchovy GSA22 fishery. This fishery is considered as fully exploited. However this has to be confirmed in following years as this assessment is based on a short time series of data and the anchovy stock should be monitored in an annual basis.
By these results we consider fishing effort should not increase beyond the current levels. This should allow to maintain the curre Fishing mortality.
Monitoring of the status of the stock with fisheries independent techniques in an annual basis is essential for this fishery.
The possibility of a change in the closed period for the survey should be examined. Shift in the closed fishing period (present: mid December to end of February) towards the post recruitment period of anchovy (e.g. October to December) or the post recruitment period of sardine (e.g. February to April) to allow the fishery to recover and more individuals of anchovy and sardine to enter the fishery at an older age.
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