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Effects of bottom trawling on fish foraging and feeding

Johnson, A.F. and Gorelli, G. and Jenkins, S.R. and Hiddink, J.G. and Hinz, H. (2014) Effects of bottom trawling on fish foraging and feeding. Proceedings of the royal Society B, 282 (1799). DOI: 10.1098/rspb.2014.2336

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Abstract

The effects of bottom trawling on benthic invertebrates include reductions of biomass, diversity and body size. These changes may negatively affect prey availability for demersal fishes, potentially leading to reduced food intake, body condition and yield of fishes in chronically trawled areas. Here, the effect of trawling on the prey availability and diet of two commercially important flatfish species, plaice (Pleuronectes platessa) and dab (Limanda limanda), was investigated over a trawling intensity gradient in the Irish Sea. Previous work in this area has shown that trawling negatively affects the condition of plaice but not of dab. This study showed that reductions in local prey availability did not result in reduced feeding of fish. As trawling frequency increased, both fish and prey biomass declined, such that the ratio of fish to prey remained unchanged. Consequently, even at frequently trawled sites with low prey biomass, both plaice and dab maintained constant levels of stomach fullness and gut energy contents. However, dietary shifts in plaice towards energy-poor prey items were evident when prey species were analysed individually. This, together with a potential decrease in foraging efficiency due to low prey densities, was seen as the most plausible cause for the reduced body condition observed. Understanding the relationship between trawling, benthic impacts, fish foraging and resultant body condition is an important step in designing successful mitigation measures for future management strategies in bottom trawl fisheries.

Item Type: Article
Subjects: Research Publications
Departments: College of Natural Sciences > School of Ocean Sciences
Date Deposited: 19 Mar 2015 03:09
Last Modified: 23 Sep 2015 02:51
ISSN: 0962-8452
URI: http://e.bangor.ac.uk/id/eprint/3664
Identification Number: DOI: 10.1098/rspb.2014.2336
Publisher: The Royal Society
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