Report of the Workshop on implementation studies on concurrent length sampling (WKISCON2)

The Workshop on Implementation Studies on Concurrent Length Sampling (WKISCON2), chaired by Liz Clarke, Scotland, and Nuno Prista, Portugal, met 16–19 June 2015 in Sukarrieta, Spain. The meeting was attended by 12 experts from nine in-stitutes, covering seven member countries.WKISCON2 originated from a request from RCM NA and the 11th Liaison Meeting to ICES WGCATCH to set up a workshop that would evaluate the utility of the data being collected by concurrent sampling. The aims of the workshop were to review the implementation of concurrent sampling for lengths by Member States (MS), identify current uses and benefits of data collected in this way, consider the statistical arguments for carrying out concurrent sampling of landings, and evaluate the implications of discontinuing current at-sea and onshore concurrent sampling. In the preparation for the workshop, two questionnaires and a data call were sent to 23 DCF National Corre-spondents (with replies from 17 institutes) and 45 ICES Expert Groups (30 replied). This evidence was analysed in subgroups and complemented with plenary discussions throughout the week.

WKISCON2 concluded that:

Overall, WKISCON2 concludes that the implementation of concurrent sampling of landings onshore and at-sea has provided benefits in terms of provision of data for more species. However, more than concurrent sampling itself, statistically sound sampling of the full range of species caught should be the overall aim of future revisions of the DCF and a return to strict stock based sampling should not be an option. To achieve statistically sound sampling of commercial catches various statistical approaches may be valid, concurrent sampling being one among them.