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The killer whale (Orcinus orca) behavior termed "depredation" is a major issue negatively affecting fisheries worldwide. Information on killer whale depredation in the northwestern Pacific Ocean is limited. The goal of this work was to assess the extent of killer whale depredation on the groundfish fisheries in the western Bering Sea and the Sea of Okhotsk. Observations of killer whale depredation were conducted on 8 of the 42 (19%) longline fishing vessels between October 2018 and September 2019. Killer whales depredated during 2.0% of vessel days in the western Bering Sea and 18.6% of vessel days in the Sea of Okhotsk, taking exclusively Greenland turbot (Reinhardtius hippoglossoides). Seventy-one killer whales were identified depredating on longlines in the Sea of Okhotsk, with the best estimation for the total number of killer whales depredating about 139 individuals. Results suggest that killer whale depredation is an issue for Greenland turbot longline fisheries in the northwestern Pacific. There is a strong need for mitigation measures, as this has an economic impact on the fisheries and also affects the killer whale population and associated ecosystems. [ABSTRACT FROM AUTHOR]

The North Atlantic Fisheries Organization (NAFO) has continuously lowered their advice regarding the Total Allowed Catch (TAC) for the coastal Greenland halibut fisheries in Western Greenland. This is due to concerns of overexploitation of the fishery. This paper investigates how the fishing intensity in the fishery for Greenland halibut (Reinhardtius hippoglossoides) in the Disko Bay, Greenland, affects the current and future income opportunities of coastal fishers. Through bio-economic modelling, I find presence of economic overexploitation of the Greenland halibut fish stock in the Disko Bay. Specifically, the actual Greenland halibut stock in 2019 is found to constitute only 56 pct. of the economic optimal stock size in the baseline scenario. The actual profit is almost 40 million DKK lower than the optimal profit due to higher costs of harvesting, which arise because the actual stock size is lower than the optimal and because of a suboptimal split of the TAC between vessels (above 6 m in length) and boats (6 m or below in length) in the fishery. The results presented in this article show that there is significant scope for economic optimization of the coastal Greenland halibut fishery through a temporary reduction in harvest of Greenland halibut to regenerate the stock to its optimal size and a transfer of TAC from the boat segment to the vessel segment. Notably, this article does not find that the stock of Greenland halibut in the Disko Bay is further decreasing at current (2019) harvest levels, however, this finding is contingent on the length of the data series used for the estimation of the growth model. [ABSTRACT FROM AUTHOR]

In this study, we investigate the type and quantity of selenium compounds in fish and marine organisms, using ion-pair reversed phase LC–ICP-MS, developed and applied for the analysis of Atlantic cod, Atlantic salmon, Greenland halibut, Atlantic herring, blue mussel, common crab, scallop, calanus, and Euphasia super . Of the samples examined, the lowest level of selenium was found in farmed Atlantic salmon (0.17 mg Se kg −1 dm). The total selenium extraction efficiency by phosphate buffer was 2.5 times higher in sea plankton and shellfish samples than in fish samples. Analysis of Se species in each hydrolysate obtained by proteolysis showed the presence of selenomethionine, which constituted 41.5% of the selenium compounds detected in hydrolysates of Atlantic herring and 98.4% of those in extracts of Atlantic salmon. Inorganic compounds, such as selenates and selenites, were detected mainly in sea plankton and shellfish samples (<0.13 mg Se kg −1 wm), although no correlation was found between the presence of inorganic compounds and total selenium concentration. The accuracy of the total selenium determination was validated using a certified reference material (oyster tissue (NIST 1566b)). A lyophilised powder of cod ( Gadus morhua ) was used to validate speciation analysis, enzymatic hydrolysis of lyophilised powder of cod recovered 54 ± 6% of total selenium, and SeMet constituted 83.5 ± 5.28% of selenium detected in hydrolysates. The chromatographic detection limits were, respectively, 0.30 ng mL −1 , 0.43 ng mL −1 , 0.54 ng mL −1 , 0.55 ng mL −1 , 0.57 ng mL −1 and 0.72 ng mL −1 for selenate, selenomethionine, selenite, Se-methyl-selenocysteine, selenocystine and selenomethionine selenoxide. The data on selenium concentrations and speciation presented here could be useful in estimating levels of selenium intake by seafood consumption. [ABSTRACT FROM AUTHOR]

Feeding ecology of Greenland halibut (Gr. halibut) ( Reinhardtius hippoglossoides) and sandeel ( Ammodytes sp.) larvae on the West Greenland shelf was studied during the main part of the productive season (May, June and July). Copepods were the main prey item for larval Gr. halibut and sandeel, constituting between 88 and 99% of the ingested prey biomass. For both species, absolute size of preferred prey increased during ontogeny. However, preferred copepod size in relation to larval length differed markedly. In Gr. halibut, the relative size of the prey declined during growth of the larvae, while it remained constant for sandeel at a level of 2.7% of larval length. This led to a reduction in prey niche overlap between the two species. The available prey copepod biomass differed distinctly across the shelf area. In May, the prey density of Gr. halibut was the highest in the off-shelf area in Davis Strait. In June and July, the prey-rich areas for both species were mainly located at the slopes of the banks and at the shelf break area. Gut fullness was higher in these areas than in neighbouring areas, suggesting that the larval food resource could be scarce. The feeding ecology of Gr. halibut and sandeel could explain why larval abundance indices of the two species have historically shown opposite responses to yearly environmental conditions and total zooplankton occurrence. [ABSTRACT FROM AUTHOR]

Maturity in adult female Greenland halibut Reinhardtius hippoglossoides was studied in three areas in west Greenland waters: the inshore area in Disko Bay and two offshore areas, Baffin Bay and Davis Strait. The aim was to monitor maturity changes in the inshore fjords of Disko Bay over an extended period from winter to autumn and compare these findings with specimens from Baffin Bay and the presumed spawning area in Davis Strait. A significant difference in maturity level was observed in and between the three areas. In Disko Bay maturity indices increased significantly in August and September both with respect to the gonado-somatic index ( IG) and the size in the leading oocyte cohort. In the period February to May no significant changes were observed. Mature ovaries were only observed among fish >80 cm total length and only among a fraction of these large fish. Offshore areas of Baffin Bay, even though poorly sampled, showed similar signs in the maturity indices as in Disko Bay. Relative to Disko Bay and Baffin Bay, female fish in Davis Strait had more progressed maturity indices. Furthermore, almost all fish in Davis Strait showed signs of progressed maturity contrary to Disko and Baffin Bay. A large proportion of the Greenland halibut in Disko and Baffin Bay apparently did not begin the maturation cycle until very late in their life history or were repeat spawners with a multi-year maturation cycle. These observations could thus support the hypothesis that Greenland halibut have a prolonged adolescent phase. Atresia was highest in the early phases of maturation in Greenland halibut but relatively high levels of atresia were also observed in fish in more advanced maturity phase. The first was ascribed to fecundity regulation while the latter could be linked to the fish's fitness condition but it was not possible to show this with the available condition index. [ABSTRACT FROM AUTHOR]