Data from two surveys and commercial catch-at-age data are used with an analytical XSA model and age-disaggregated indices in the assessment of the stock (ICES, 2008a, 2009). Two commercial CPUE series are available but have not been used as they are dependent on environmental, price differential or other factors, but they show a similar overall tendency to the survey series (ICES, 2008b).
The sampling is thought to be adequate although a larger number of samples could be aged but data input to the model is of high quality, as is the assessment itself (ICES, 2008b).
According to ICES, the current strategy of harvesting 33% of the exploitable stock of cod translates into a fishing mortality of 0.45, above the precautionary fishing mortality (0.35), which is inconsistent with the precautionary approach (ICES, 2009, 2013a). Given the poor state of the stock and weak recruitment, ICES advice has been to reduce fishing mortality (F) to allow stock rebuilding. For 2014, ICES has recommended a decrease in fishing effort so that F will be less than 0.16, which corresponds to a 69% of the current fishing mortality. Additionally, a recovery plan will be necessary, aimed at rebuilding the stock to above MSY Btrigger as quickly as possible (ICES, 2009, 2013a,b). According to ICES, the management plan should incorporate strategies for a stepwise reduction of F to Fmsy by 2015, and also an harvest control rule if the SSB declines below MSY Btrigger (ICES, 2013a).
The following reference points have been defined for the stock, having remained unchanged since 2011 (ICES, 2013a):
|Precautionary approach||Blim||21,000 t|
|MSY approach||MSY Btrigger||40,000 t|
There is no specific fishing mortality (F) target reference point, but according to ICES the effort regulation scheme in place assumes a annual harvest of around 33% of the exploitable stock, which renders into an average F of 0.45.
The basis for the value of Blim was the lowest observed SSB level from which the stock had recovered at the time of the definition of the reference points, in 1998. Bpa= Blime1.645σ and Flim= Fpae1.645σ, assuming an σ of about 0.40 to account for the large uncertainties in the assessment. Fpa was set close to Fmax (0.34) and Fmed (0.38) from the 1998 assessment. The target fishing mortality, Fy, is (ICES, 2008a). Preliminary MSY reference points were also adopted in 2011 (ICES, 2013a,b).