Further, the focus was also on estimating damages that can be caused by intensive bottom trawling taking place in areas inhabited by snow crabs. Finally, initial testing by using biodegradable plastic materials in pots and bottom trawls were carried out during this time to test whether the new materials can be used to reduce marine plastic pollution. The participants involved scientists and students from UiT The Arctic University of Norway and Heriot-Watt University and a senior advisor from the Norwegian Directorate of Fisheries.
Part of this research trip focused on research building upon earlier results that were obtained by SFI Dsolve and within UArctic networking project “Networking for increasing sustainability in snow crab fisheries in the Arctic” slightly more than a year ago (more information about that is available here: https://dsolve-sfi.no/en/uarctic-project-workshop-held-onboard-rv-helmer-hanssen). Specifically, the present research focused on testing different escape gap sizes in the snow crab pot fishery. Our estimates can be included to supplement the current knowledge and provide an insight of what is the most optimal escape gap size and design for optimally exclude undersized and small snow crabs while the pots are on the seabed considering minimum size regulations and the requirements by Norwegian snow crab fishery. This knowledge will be valuable for further developing escape gaps made of biodegradable plastic materials in collaboration with NORNER AS within the newly funded FHF project “Develop, produce and test biodegradable escape gaps for snow crab pots”.
This development of using biodegradable materials instead of non-biodegradable materials such as high-density polyethylene plastic when producing escape gap plates is crucial for reducing plastic pollution and potential continuous capture (“ghost fishing”) by derelict snow crab pots (see earlier estimates of ghost fishing in snow crab fishery here: https://dsolve-sfi.no/en/new-study-estimates-the-extent-of-ghost-fishing-in-the-snow-crab-fishery). The degradation of the material would make a larger area available for snow crab escapement, effectively reducing ghost fishing of larger snow crabs. This will also supplement escape opening from use of biodegradable twine, a regulation introduced since 2024 in snow crab pot fishery. During our research cruise, we also tested the potential use of fully biodegradable plastic netting in pot construction, and wood fibre ropes produced by Norsk Fletteri AS around the top and bottom ring. We plan to continue these tests of biodegradable pot material durability, both escape gap plates, netting and ropes, onboard a commercial fishing vessel later during this fishing season.
Since snow crab fishery in Norwegian part of the Barents Sea takes place in an area that is used for bottom trawling for capture of Deep water shrimps outside the snow crab fishing season, the question is whether bottom trawling can negatively impact snow crab habitats. These effects can be caused by both, direct damage to snow crab of different sizes and by resulting plastic pollution in the area and thus is increasingly of relevance to address. Over the last years a large number of modern trawlers have exploited the traditional shrimp grounds for several weeks in areas now also inhabited with snow crab.
Modern shrimp trawling is performed with large trawls in double or triple configurations. Each trawl has a heavy rockhopper footrope and between each trawl a centre weight of several tons enables correct geometry and bottom contact between the otter boards. A modern triple trawl configuration weigh 30-40 tons in air and there are questions about how the intensive trawling in these areas affect the snow crab stock. Microplastics from synthetic rubber, nylon and polyester produced by bottom trawling and other fisheries are likely to end up in the diet for fish, shrimps and crabs. A study made in the Pechora Sea (Russia) found that 35% of captured snow crab had ingested plastics ((Research): Microplastics in the Arctic Benthic Fauna: A Case Study of the Snow Crab in the Pechora Sea, Russia | Springer Nature Link).
More information on the findings from this research trip will follow.
