Working Group on the Integrated Assessments of the Barents Sea (WGIBAR)
reportposted on 2019-01-01, 00:00 authored by ICESICES
Since the 1980s, the Barents Sea has gone from a situation with high fishing pressure, cold con-ditions and low demersal fish stock levels, to the current situation with high levels of demersal fish stocks, and warm conditions.Ecosystem state: The ongoing warming was associated with increased water and air tempera-ture, larger area covered by Atlantic (>3°C) and Mixed (0-3°C) warm water masses and decreased ice coverage both during winter and summer. The warming was also associated with increased primary and secondary (macro zooplankton such as krill and jellyfish) production, increased fish recruitment (age 0) which triggers positive development of fish stocks (cod, haddock, deep water redfish, capelin and herring). Increased production and adequate fishing pressure in relation to stock size led to cod and haddock stock size increasing to record high levels and the capelin stock withstanding the high predation level. Large fish stocks have distribution ranges extending fur-ther north, where feeding environmental conditions were suitable due to warming. The number of whales, which use the Barents Sea as summer feeding area, increased or stabilized in last dec-ades. Several seabirds populations from coastal colonies stay or migrate in to the Barents Sea to feed and moult, possibly increased in total number. Arctic fish and benthos communities showed opposite trends, decreased in numbers and distribution most likely due to increased predation and competition pressure from boreal species. A true arctic fish, polar cod, showed decreased stock size and recruitment failure in the traditional area, the south-eastern Barents Sea. Reduc-tion of ice cover and warmer temperature condition in addition to increased predation from a large cod stock are some of reasons for the polar cod stock decrease.Human pressure: The assessment for several commercially important stocks indicated that the stocks has been fished sustainably and have remained well above precautionary reference limits. The present (2016–2021) minke whale quota is considered precautious, conservative, and protec-tive for the minke whale population in the Northeast Atlantic. Catches of harp seals in recent years have been much lower than the quotas. The AIS tracking of vessel in the Barents Sea in August, 2012 to 2018, indicated an increased fisheries effort east of Svalbard and also an increase in passenger vessels to the Svalbard area. The effect on the marine ecosystem of the increased tourist traffic is not known, but the possibility for more littering is a potential risk. Large-scale monitoring of marine litter since the 2010, showed that plastic dominated number of observa-tions with marine litter, while textile, paper, rubber and metal was observed occasionally.Expected changes in the coming years: Oceanic systems have a “longer memory” than atmos-pheric ones. According to the expert evaluation, the Atlantic water temperature in the Murman Current is expected to decline slightly but remain typical of warm years. Due to high tempera-tures and low sea-ice extent in recent years, the ice coverage of the Barents Sea is expected to remain below normal. The WGIBAR group updated most of the time-series data and established additional time-series for the oceanographic conditions, mesozooplankton and 0-group fish, based on WGIBAR-subar-eas for the Barents Sea. The WGIBAR working group provides knowledge of the status, changes, relationships, and processes in the ecosystems to the Joint Russian-Norwegian Fisheries Com-mission, the Joint Russian-Norwegian Environmental Commission, the Norwegian Ministry of Climate and Environment, fisheries organizations, and different ICES working groups and dis-seminates their results at scientific conferences and by scientific publications and public papers.
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