Benchmark workshop on capelin (WKCAPELIN)
The benchmark workshop on capelin (WKCAPELIN) was set up to develop benchmark assessments for the Barents Sea capelin and the Iceland-East Greenland-Jan Mayen capelin stocks. These stocks are distributed in ICES subareas 1, 2, 5, and 14.
For Barents Sea capelin, a modification of the existing model approach, which includes multispecies elements (predation by cod), was generally endorsed. Changes to the model approach that were endorsed in the meeting included using a type III rather than type II consumption model; a time averaged (most recent 5 years) CV at age for the autumn survey; 14 cm was to be used as the maturation length cut-off; M and F were now assumed to be constant from January to March; and the year used for the Blim calculation was changed to avoid the early period of the time-series with a low herring stock. Despite these changes, the model results are relatively consistent with the previous assessment.
For Iceland-East Greenland-Jan Mayen (IGJM) capelin, a modified version of the existing model approach, which includes multispecies elements (predation by cod), was generally endorsed. The Autumn survey now has a maximum weight of 1/3rd in the final assessment. The revised model has lower biomass levels and Blim than the previous assessment, but the relation between Blim and average SSB is largely unchanged.
Both stocks are managed as escapement strategy fisheries, with Bescapement based on Blim. The only defined reference point is therefore Blim, and there are no F reference points. Bpa is not needed for either stock, as the HCRs are explicitly based on having a 95% chance to avoid going below Blim.
The workshop evaluated that the approach taken by Barents Sea and IGJM represents best available science following ICES procedures. The two existing HCRs are considered as precautionary as is typical for any ICES escapement strategy. Furthermore, the HCRs have functioned successfully for a number of years (since 1991 for Barents Sea, and since 2015 for IGJM). Provided no significant change is made to the HCR or to the performance of the underlying models, the rule should continue to be as precautionary as previously. It should be noted that the Blim for the Barents Sea previously included a safety factor, raising Bescapement to 200kt. Following current ICES procedures, the safety factor is no longer included in the Blim value. However, the evaluation here that the existing HCR remain precautionary is based on a HCR in which Bescapement retains the safety factor (i.e. remaining at 200kt). Any alternate HCR would require a separate evaluation.
Published under the auspices of the following ICES Steering Group or Committee