Report of the Inter-Benchmark Protocol on New Species (Turbot and Sea bass

• Main Author: ICES
• Format: Text
• Language: English
• Subjects: envir; geo; Kattegat; Turbot
• Online Access: https://archimer.ifremer.fr/doc/00124/23485/21314.pdf; https://archimer.ifremer.fr/doc/00124/23485/

Inter-Benchmark Workshop on NEW species (IBPNEW) met in Copenhagen (Den-mark) from 1–5 October 2012 to perform a benchmark assessment on the stocks of turbot and sea bass. All the terms of reference were addressed. In hindsight, the five days that were available for this workshop were too short. Although most work re-garding the ToRs was finished before the end of the workshop, large parts of the report still needed to be finished at the end of the meeting, and this caused consider-able delay in the delivery of the final report. For turbot in the North Sea ecoregion, the group recommends that turbot from the Skagerrak/Kattegat is not included in the Greater North Sea stock, but treated sepa-rately or combined with the Baltic stock. This recommendation is based on considera-tions of the life-history characteristics of turbot (low larval dispersal, strong spawning site fidelity, limited migrations of the species) and the observed genetic patterns. The western limit of the North Sea stock would remain between IVc and VIId. Further progress on the assessment of turbot in IIIa could be made in WGNEW or WGBFAS. Landings, effort and survey index data for Turbot in Area IV were collated. These data were made available by earlier working groups and projects, such as ICES WGNEW and the NESPMAN project. Two different stock assessments were per-formed on the data: ASAP (NOAA toolbox) and a spline-based statistical catch-at age model. The spline-based statistical catch-at-age model was proposed as a model to be used in future WGNSSK groups. The model is run on the landings-at-age data avail-able since 1975 combined with the BTS-ISIS and SNS survey indices and the Dutch beam trawl fleet cpue as tuning indices. Given the assessment model results, the FMAX reference point on the yield-per-recruit curve was estimated and was well-defined. The assessment results indicate that the fishing mortality in the most recent years has been higher than FMAX. No short-term forecast methodology was proposed, and when used for management ...