Development of sustainable fisheries management and monitoring for sensitive soft-bottom habitats and species in the Kattegat
The Kattegat is home to an intensive bottom trawl fishery for Norway lobsters ( Nephrops norvegicus ), and although the fishery on the target species is sustainable, intensive bottom trawling is known to significantly impact sensitive seabed habitats and species. In this project, we investigated how...
| Main Authors: | , , , , , |
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| Format: | Book |
| Language: | English |
| Published: |
DTU Aqua
2020
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| Subjects: | |
| Online Access: | https://orbit.dtu.dk/en/publications/f152dbab-bfc8-4daa-92e3-2957a2583784 https://backend.orbit.dtu.dk/ws/files/219133507/372_2020_Development_of_sustainable_fisheries_management_and_monitoring_for_sensitive_v2.pdf https://www.aqua.dtu.dk/-/media/Institutter/Aqua/Publikationer/Rapporter-352-400/372-2020-Development-of-sustainable-fisheries-management-and-monitoring-for-sensitive-v2.ashx |
| Summary: | The Kattegat is home to an intensive bottom trawl fishery for Norway lobsters ( Nephrops norvegicus ), and although the fishery on the target species is sustainable, intensive bottom trawling is known to significantly impact sensitive seabed habitats and species. In this project, we investigated how bottom trawling for N. norvegicus affects the seabed fauna and the demersal fish assemblages in the Kattegat by sampling selected stations with bottom grabs and trawls, by recording the fauna on the seabed with a towed video camera, and by counting and identifying the species attracted to baited stereo-video cameras. The sampling stations were primarily located in the deeper, soft sediment areas where N. norvegicus is abundant, but samples were also collected in shallower areas where sensitive species had been identified in previous investigations. Prior to sampling, local fishers were interviewed to identify potential areas of N. norvegicus habitats that were ‘de facto’ closed to fishing due to the presence of obstacles on the sea bed, such as reefs and boulders. In some of these areas, side scan sonar was used to map the seabed. Results from previous investigations and maps of fishing intensity were used to select the sampling locations, in order to ensure that a bottom fishing pressure gradient ranging from zero to high intensity was represented in the sampling design. Four different sampling devices were deployed to compare their individual suitability to record different elements of the seabed and demersal fauna. The sediment grab sampler mostly contained invertebrate species that dwell in the sediment (infauna) and some of those which reside on the surface of the seabed (epifauna). The towed video camera primarily recorded the larger (megafauna) epifaunal species. These included epifaunal invertebrate species known to be sensitive to bottom trawling, such as sea pens ( Virgularia mirabilis, Pennatula phosphorea ), northern horse mussel ( Modiolus modiolus ), tube building crustaceans ( Haploops spp.), and ... |
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