Working Group on International Deep Pelagic Ecosystem Surveys (WGIDEEPS)

The objective of The Working Group on International Deep Pelagic Ecosystem Surveys (WGIDEEPS) is to plan and conduct international deep pelagic ecosystem surveys in the Irminger Sea and adjacent waters and in the Norwegian and Barents Seas. The main focus of the group is to measure abundance and map the distribution of beaked redfish (Sebastes mentella). The participating nations are Germany, Iceland, Norway and Russia.The group had some success transferring data from the WGIDEEPS surveys into the ICES-DATRAS data-base including the Norwegian Sea International Deep Pelagic Surveys (NS-IDPS) for 2009, 2013, and 2016, and the Icelandic Irminger Sea International Deep Pelagic Surveys (IS-IDPS) for 2009. This will allow for future efficient and transparent access to WGIDEEPS data.The group discussed a new method for the estimation of abundance and biomass of redfish in the deeper layers in the Irminger Sea. Testing of this proposed method should be a future goal.The group also aimed to set up a formal procedure for the use and transfer of Norwegian survey data to other ICES groups including Arctic Fisheries Working Group (AFWG) and The Working Group on the Integrated Assessments of the Norwegian Sea (WGINOR). Estimated numbers-at-age from the pelagic sur-vey in the Norwegian Sea were presented at the 2018 benchmark assessment and used in the analytical assessment for the stock.The 2017 Workshop on Monitoring Technologies for the Mesopelagic Zone (WKMESO) improved collabo-ration with other ICES expert groups and WGIDEEPS plans to continue developing pathways for improved coordination.The working group also worked on planning and reporting of the surveys in the Irminger Sea and Norwe-gian Sea. The Irminger Sea survey was planned during the meeting in February 2018, was conducted in June/July 2018 and the outcome of the survey was published in the WGIDEEPS interim report in August 2018. Originally, Germany, Iceland and Russia planned to carry out the survey, but technical and other problems meant that Iceland and Germany were not able to participate. Accordingly, the scope of the sur-vey had to be altered and the emphasis was on the detailed coverage of the pelagic redfish above and below 500 m depth in in the northeast part of the survey area. About 103 000 NM2 were covered compared to 340 000 NM2 in 2013.The survey in the Norwegian Sea conducted by Norway in August 2019 showed (1) the extended survey area still does not cover the full extent of the population of beaked redfish in the Norwegian Sea, (2) biomass estimates for 2019 are back in the range of surveys prior to 2016, suggesting that the low estimates for 2016 are due to the bulk of the population being out of the survey area or due to methodological reasons, (3) the observed length structure and the slightly reduced mean length suggest that both the old fish in the popu-lation and the new cohorts observed in 2016 are growing and that young fish become more important nu-merically as the mean length is reduced.