The data used in the assessment are from catch-at-age and one age-structured acoustic survey index performed on an Age-based analytical model (NFT-ADAPT). The stock size was overestimated for many years resulting in TAC advice that lead on average to a higher fishing mortality (F) than intended by the target (F0.1= 0.22). Contrarily to the previous assumptions, the Ichthyophonus infection is now estimated to have caused significant infection mortality in 2009-10. Despite the remaining uncertainties in the estimates of the 2008 and 2009, the quality of the assessment has improved. Discards are considered ‘negligible’, thus not included in the assessment (ICES, 2013a). A domestic stock assessment and scientific advice are also provided annually by the Icelandic Marine Research Institute (MRI).
ICES advice for 2008/2009 and 2009/2010 was to keep fishing effort at Fpa corresponding to a catch of 131,000 and 75,000 tonnes, respectively. For the 2011/2012 season, no initial advice was provided by ICES in light of the assessment uncertainty associated with the Ichthyophonus infection (ICES, 2012a). But the prevalence of Ichthyophonus infection was then considered much lower, and infection mortality to only have been significant in 2009 and 2010. Based on this assumption that the stock is currently well above the reference points, ICES has recommended, on the basis of the MSY approach, catches in 2013/2014 of no more than 87,000 tonnes (ICES, 2013a).
F0.1 (= 0.22), which has been used as the target fishing mortality (Fpa) for many years, forming part of the present management strategy, is considered by ICES to be consistent with the MSY approach (ICES, 2012a).
The following biological reference points have been defined for this stock: Blim = 200,000 tonnes; Bpa=MSY Btrigger = 300,000 tonnes. Fpa(=F0.1) =0.22, which has been used as a target. FMSY was recently estimated and is the same as Fpa (= 0.22) (ICES, 2012a).
According to the latest assessment, the stock is being harvested “sustainably” and at “full reproductive capacity” (ICES, 2013a). The 2012 fishing mortality was estimated at 0.22, i.e., at Fpa = 0.22. After a decreasing trend from 2008 to 2011 (likely due to the Ichthyophonus infection that affected the stock) spawining biomass has increased since and is currently well above the reference pints MSY Btrigger (=Bpa). SSB in the beginning of 2013 was estimated at 541 thousand tonnes, well above the reference points. The latest recruiting year classes are strong and apparently have not been affected by the Ichthyophonus infection (ICES, 2013a; MRI, 2013).
Fishing mortality (F) was above Fpa during most of the time series until 2008, but has decreased sharply in 2009 (F = 0.08). It has been increasing since and is currently at Fpa. Spawning biomass was in high levels until 2008, but decreased considerably from 2009 to 2011 likely due to mortality associated with Ichthyophonus infection of the stock. As a result, and due to more restrictive TACs between 2009 and 2012, landings also decreased considerably during this period, from around 150 thousand tonnes to around 45-50 tonnes. The infection seems however to only have significantly affected the stock during 2009-10 and SSB has been increasing since 2011. In 2013, SSB was estimated to be well above Bpa (ICES, 2013a,b).