International Council for the Exploration of the Sea
WGIBAR 2015_Full report.pdf (285.94 kB)

Second Interim Report of the Working Group on the Integrated Assessments of the Barents Sea (WGIBAR)

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posted on 2015-01-02, 00:00 authored by ICESICES
The Working Group on the Integrated Assessments of the Barents Sea (WGIBAR), met from 1–4 June 2015 at Kirkenes, Norway, to assess the state of the Barents Sea (BS). The BS is currently changing and the state differs from previous periods. The recent period is characterized by warming, decreased ice cover, expansion of boreal stocks north-wards into the Arctic subregion of BS, large and thriving stocks of cod, haddock and capelin, and moderate fishing pressure. Main points are:• 2014 was relatively warm, although cooler than the peak year 2012. Bottom temperature was above the long-term mean for most of the BS, whereas sea surface temperature was below average in the northeastern BA.• In 2014, stronger than usual northwesterly winds prevailed. This caused ice cover in September to be the largest for the last 20 years, which restricted survey coverage and led to highly uncertain stock estimates of capelin and polar cod.• The mesozooplankton biomass shows a slight decline since 2006, but was still at a relatively high level in 2014. The declining trend reflected a decrease in the proportion of large mesozooplankton, indicating a significant ecolog-ical change to smaller zooplankton forms, which are of less value to plank-ton-eating fish.• Krill has been at a relatively high level in the recent warm period (since 2004), but the 2014 data suggest a substantial decline. Pelagic amphipods (in particular Themisto libellula) declined significantly in recent years. Declines in these macrozooplankton groups are expected to have trophic conse-quences for many consumers in the BS foodweb.• Capelin is the major grazer of zooplankton in the BS, with high biomass (>3*106 t) over the past 7 years resulting in high predation pressure on zoo-plankton. Capelin stomach fullness and growth has decreased in the recent years, possibly reflecting qualitative changes in the zooplankton commu-nity.• The cod stock is currently large (~3.5*106 t). Along with a high biomass of haddock, the increase in the cod stock has led to a declining trend in the ratio of pelagic to demersal fish biomass (currently about one-to-one).• The large cod stock exerts a strong predation pressure on capelin (estimated annual consumption ~3.5*106 t in 2014). The recruitment of capelin has been good in recent years, and the capelin stock has sustained the high cod pre-dation. However, in 2014 the 0-group index of capelin was below the long-term mean.• Polar cod has shown a strong decline in recent years, from a peak of ~2*106 t around 2006. As a key species, this is likely to have major trophic implica-tions in the foodwebs of the northern BS.• Minke whales, harp seals and cod are main piscivores in the BS, and as the cod stock has grown the condition of the other two species has declined.• Snow crab are increasing in abundance and expanding westwards.• Catches of capelin, cod, haddock, redfish, Greenland halibut and shrimp were about 1.3*106 t in 2014, a decrease from the peak in 2011 (1.5*106 t ).• Fisheries management plans are implemented for all main stocks in the re-gion.


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