Working Group on International Deep Pelagic Ecosystem Surveys (WGIDEEPS)

The Working Group on International Deep Pelagic Ecosystem Surveys (WGIDEEPS) plans and reports on the international hydroacoustic-trawl surveys on pelagic redfish in the Irminger and Norwegian seas.
The detailed planning of the international trawl/acoustic survey on pelagic redfish in the Irminger Sea and adjacent waters in June/July 2021 has been agreed by all participating countries. Prior to the meeting, the Icelandic delegation informed group members that Iceland will not participate in the June/July 2021 IDEEEPS. To cover the whole distribution area of pelagic redfish in the Irminger Sea a minimum three vessels are needed. The scope of the survey therefore needed to be altered and will be carried out in a similar manner as in 2015 where the emphasis is on covering the main distribution area of redfish in the north and south-eastern area (subareas A and B) and part of the south-western area (subarea E). Two vessels from Germany and Russia will participate in the survey and operate within an area of around 270 000 square nautical miles (NM2) in the Irminger Sea to estimate the abundance and biomass of pelagic redfish (Sebastes mentella). In the depth zone that can be surveyed by hydroacoustic measurements, i.e. shallower than the deep-scattering layer (DSL; down to about 350 m), hydroacoustic measurements and identification trawls will be carried out. Within and below the DSL (down to about 950 m), redfish abundance will be estimated by trawls. The trawl method applied is the same as in the 2009- 2018 surveys and is in line with the recommendation from ICES to study separately the stocks shallower and deeper than 500 m. As in past surveys, biological data will be collected from the redfish caught in the pelagic trawls, and hydrographical measurements will be taken on regular stations on the survey tracks.
Work on a more direct approach to biomass and abundance estimation was presented and discussed at the meeting, but no decision was taken on applying the new method for the estimation of biomass and abundance of the deep pelagic stock. Additionally, two alternative methods of standardizing the biomass index were presented and discussed, but no decision was taken on applying an alternative method in the index estimation.
It was recognized that the methods presented to the group should best be presented, discussed and tested for their applicability at a future benchmark of redfish stocks.