Working Group on the Ecosystem Effects of Fishing Activities (WGECO)

• Main Authors: Calderwood, Julia, Collie, Jeremy, Croll, Jasper, Greenstreet, Simon P. R., Griffiths, Christian, Kenchington, Ellen, Kooten, Tobias van, Lynam, Christopher P., Moriarty, M., Ragnarsson, Stefán Áki, Reid, David G., Rindorf, Anna, Savina-Rolland, Marie, Sarrazin, Victoria, Shephard, Samuel, Smith, Brian, Thompson, Murray
• Format: Book
• Language: English
• Published: International Council for the Exploration of the Sea (ICES) 2019
• Subjects: /dk/atira/pure/sustainabledevelopmentgoals/life_below_water; SDG 14 - Life Below Water; /dk/atira/pure/sustainabledevelopmentgoals/life_on_land; SDG 15 - Life on Land; Jeremy; Tora; Iceland
• Online Access: https://orbit.dtu.dk/en/publications/46feb0ae-c03b-403d-90ed-59b5ffa38b27; https://doi.org/10.17895/ices.pub.4981; https://backend.orbit.dtu.dk/ws/files/201163750/wgeco_2019.pdf

The 2019 meeting of WGECO was held at the International Council for the Exploration of the Sea, Copenhagen, Denmark from 8–16 April 2019. The meeting was attended by 16 delegates from eight countries and was chaired by Stefán Ragnarsson (Iceland) and Jeremy Collie (USA). The work conducted centred on three Terms of Reference that had been made by WGECO. In addition, a list of sensitive species prepared by WGBYC was reviewed. WGECO continued the work initiated in 2018 to examine the ecological consequences of stock rebuilding, with emphasis on benthivorous fish (ToRa). Two case studies were carried out to estimate the predation pressure of fish on benthos. In one, the consumption of benthic invertebrates by demersal fish on the US continental shelf regions was compared with their biomass in sediments. The estimated annual consumption of benthic organisms was a small proportion (<5%) of total abundance for most taxa but as high as 25% for some prey. Benthic food resources do not appear to be limiting the feeding of benthivorous fishes. The second study examined the temporal trends in diet composition and consumption rates of haddock, which has experienced a northerly shift in abundance in Icelandic waters. Some prey types showed clear trends from 2006 to 2019, while others had more variable patterns. Consumption rates of benthic invertebrates, fish and zooplankton/natantia prey types were calculated. The much greater consumption of fish prey relative to the other two prey groups was of interest. WGECO scrutinized methods to estimate density-dependent effects on fish growth and made suggestions on its estimation from stock assessment or survey data. A simulation study showed that the age-specific growth increment may not be a useful variable to test for density-dependent growth, because it depends on body size. In the WGECO 2018 report, the case had been made that North Sea plaice show density-dependent growth reduction. In 2019, we conducted a more thorough analysis of the spatial and temporal trends in ...