Direct effects of beam trawling on macrofauna in a soft bottom area in the southern North Sea
van Santbrink, J.W.; Bergman, M.J.N. (1994). Direct effects of beam trawling on macrofauna in a soft bottom area in the southern North Sea. BEON Rapport = BEON-report, 13. Programma Bureau BEON: Den Haag. 4-44 pp.
Deel van: BEON Rapport = BEON-report. Programma Bureau BEON: Den Haag. ISSN 0924-6576, meer
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| Auteurs | | Top |
- van Santbrink, J.W.
- Bergman, M.J.N.
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| Abstract |
Direct effects of trawling with commercial 12m beam trawls on the abundance of benthic species in soft bottom area in the southern North Sea were studied by comparing densities before and after trawling. Various sampling gears were used, including a benthos dredge (Triple-D) developed especially for this study. After trawling a study area twice, mortality could be estimated for a number of species. For fish species mortality varied from 4% (small fish) to 75% (larger fish) of the numbers initially present. Mortality exceeded 100% for dab, Limanda limanda, as it rapidly immigrates into trawled area already during trawling. For invertebrate species, mortality was variable as well, and estimated at 3-19% for echinoderms, 0-85% for molluscs, 4-74% for crustaceans, < 1-56% for annelids, and 70% for anthozoans. Dab was a predominant scavenger on damaged or exposed fauna on the recently trawled seabed. The presence of infauna species in catches of the 12m beam trawls indicated, that sediment was disturbed by the tickler chains to a depth of approximately 2 to 4cm. |
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