The snow crab ( Chioneocetes opilio ) fishery in the Barents Sea is carried out by large offshore vessels, as the fishing grounds are located far from shore and the gear must be transported back and forth over long distances. Therefore, fishers use stackable conical pots that allow large numbers of pots to be carried on deck for each trip. One of the drawbacks of using stackable pots is that the entrance is at the vertex of the conical pot, which fishers claim does not provide the desired fishing efficiency. Thus, the goal of this study was to determine whether a different pot design would improve the catch efficiency of snow crabs. We investigated the efficiency of a new type of pot called the moon pot, which provides continuous increased bait odour intensity as snow crabs make their way towards the entrance of the pot. This alteration was expected to increase catch efficiency compared to that of the conical pots used by the fleet today. However, experimental fishing results showed that the modified pots had significantly lower catch efficiency than the standard conical pots, as only ~66% of the number of crabs caught by the conical pots were caught in the moon pots. The main reason for this reduced catch efficiency likely was the initial steepness of the moon pot, which may have made it difficult for crabs to reach the pot entrance. These results demonstrated that pot design can dramatically affect catch efficiency of snow crabs.
Sorting grids and square mesh panels are the two most-applied technical devices to supplement codend size- and species-selection in demersal trawls. In the Barents Sea gadoid fishery, the compulsory size-selectivity system comprises a mesh section with a sorting grid followed by a diamond mesh codend. We tested the size-selective performance of a new sorting section that comprised a sorting grid combined with a square mesh panel as a potential alternative for the grid sections currently in use. The new sorting section was shorter and therefore more maneuverable than the existing sorting grid sections. The investigation was carried out on cod and the bycatch species redfish. The grid was found to contribute to the largest proportion of fish release, and the release through the square mesh panel was low. But, the results showed that the grid was successful at guiding fish not escaping through the grid to a second selection process in the panel. However, the square mesh panel did not result on the intended release efficiency except for the smallest sizes of fish, most likely because the guiding angle of the grid and the square meshes in the panel used did not provide a suitable escape path for the desired size range of fish. Therefore, optimizing the mesh size/shape in the panel and/or the guiding angle for the grid potentially could lead to the desired selectivity pattern in the new sorting section.
Commercial harvesting of snow crab (Chionoecetes opilio) in the Barents Sea started in 2012 by Norwegian fishing vessels. This new fishery has significant bait requirements, representing an emerging conservation challenge. In this study, we evaluate the performance of five alternative (natural) baits manufactured from the waste stream of existing and sustainably managed harp seal (Pagophilus groenlandicus) and minke whale (Balaenoptera acutorostrata) capture. Five different types of new bait were evaluated, including seal fat (SF), seal fat with skin (SFS), seal meat with bone (SMB), whale fat with skin (WFS), and whale meat with fat (WMF). A comparative fishing experiment was conducted onboard a commercial snow crab fishing vessel in the Barents Sea (May–June, 2016) to evaluate the performance of traditional bait (squid, Illexs spp.) and alternative baits at catching snow crabs. Performance of the different baits were compared on the basis of the number of commercial crab caught per trap haul catch per unit effort (CPUE) and carapace width (CW). Our results showed that SF and SFS performed equally well to traditional bait, with no statistical difference in CPUE (p-value = 0.325 and 0.069, respectively). All of the other experimental baits significantly decreased CPUE, when compared to squid. No significant effect of bait treatment on CW was detected and the cumulative distribution of CW was the same between control traps and each of the bait treatments. Overall the results indicated that SF and SFS represent a viable alternative to replace traditional bait, addressing a key conservation challenge in this bait intensive snow crab fishery.
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