35 research outputs found
Barents Sea Shrimp - stock assessment report 2022/23
Since the 1980s, the Barents Sea has gone from a situation with high fishing pressure, cold conditions and low demersal fish stock levels, to the current situation with high levels of demersal fish stocks, reduced fishing pressure and warm conditions.Barents Sea Shrimp - stock assessment report 2022/23publishedVersio
Infaunal and epifaunal secondary production in the Barents Sea, with focus on snow crab (Chionoecetes opilio) prey resources and consumption
Since the first observation of snow crab (Chionoecetes opilio) in the Barents Sea in 1996, the population has increased significantly, supporting a commercial fishery on the Norwegian shelf since 2012. To investigate whether the availability of benthic prey organisms may support a continued geographical snow crab expansion, benthic invertebrate production was studied across the central parts of the Barents Sea and around Svalbard, where snow crabs are currently absent or at low densities. Annual productivity (P/B ratio) from 66 stations collected by grab and beam trawl was estimated using a multiparameter artificial neural network model. Mean infaunal productivity and production were 0.43 yr−1 and 38.4 g ww m−2 yr−1, respectively, while the epifaunal production was considerably lower with 2.5 g ww m−2 yr−1. The proportions of epi- and infaunal production suitable as prey for snow crab were 98 and 96%, respectively. Areas close to the Polar Front represent the most attractive snow crab foraging region, having the highest benthic secondary production, high estimated primary production, and bottom water temperatures within the snow crab’s preferences. At snow crab densities of 12800 ind. km−2, high enough to support commercial fishing, their mean consumption rate was estimated to be around 1.5 g ww m−2 yr−1, which amounts to 4% of mean infaunal prey production. Food availability is, therefore, not expected to be a hindrance to further population expansion of the snow crab in the Barents Sea.publishedVersio
Assessment of the Cod Stock in NAFO Division 3M
An assessment of the cod stock in NAFO Division 3M is performed. A Bayesian model, as used in the last
assessments, was used to perform the analysis. As there are inconsistencies with total catch of last year, a prior was
added for 2011 catch. Results indicate a fairly substantial increase in SSB, reaching a value well above Blim. The sixyears
retrospective plot shows that the recruitment is overestimated every year. Three year projections indicate that
fishing at the Fstatusquo level should allow SSB to increase slowly, although abundance will remain at levels below
those observed at the beginning of the series. If the fishing mortality were return to the levels seen before 1995,
stock recovery would become improbable
Modelled dispersal of snow crab (Chionoecetes opilio) larvae and potential settlement areas in the western Barents Sea
Since the mid-1990s, a snow crab (Chionoecetes opilio) population has established in the eastern Barents Sea. Spawning females and newly hatched larvae are now also found in the central Barents Sea, warranting speculations on a further westward colonization by pelagic larvae. Here, we model the potential for larval dispersal and settlement into uncolonized areas in the western Barents Sea. We used a biophysical model of ocean currents and hydrography, coupled with a Lagrangian dispersal algorithm and larval survival functions as response to temperature. The model predicts limited dispersal from the central Barents Sea to western areas, primarily due to a mismatch between prevailing temperature regimes and temperature tolerances for the different larval stages. In addition, there was limited westward transport of water masses with temperatures that would allow completion of the pelagic larval development. We speculate that for larvae to successfully supply benthic recruits to the remaining uncolonized areas in the western Barents Sea, adult crabs would first need to establish new spawning aggregations, for example along the western slopes of the Barents Sea shelf. Immediate implications are limited potential for expanding the fishery to the western areas of the Barents Sea.publishedVersio
Assessment of the Cod Stock in NAFO Division 3M
An assessment of the cod stock in NAFO Division 3M is performed. A Bayesian model, as used in the last
assessments, was used to perform the analysis. As there are inconsistencies with total catch of the last three years,
a prior was added for 2011 and 2012 catch and the Daily Catch Report data were used in 2013. Results indicate a
general increase in SSB since 2005, reaching a value well above Blim since 2009