Journal Article

Management implications of interactions between fisheries and sandeel-dependent seabirds and seals in the North Sea

Robert W. Furness

in ICES Journal of Marine Science

Published on behalf of ICES/CIEM

Volume 59, issue 2, pages 261-269
Published in print January 2002 | ISSN: 1054-3139
Published online January 2002 | e-ISSN: 1095-9289 | DOI: http://dx.doi.org/10.1006/jmsc.2001.1155
Management implications of interactions between fisheries and sandeel-dependent seabirds and seals in the North Sea

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The lesser sandeel, Ammodytes marinus, is a key food for many seabirds and seals, and is also the target of the largest single-species fishery in the North Sea. Despite claims that sandeel fishing has harmed dependent predator populations, census data show that most seabirds and grey seals increased in numbers as the fishery grew and reached peak harvest. Generally high breeding success of black-legged kittiwakes at North Sea colonies also suggests that sandeel abundance has remained good for breeding seabirds at the broad scale, though local and small-scale effects of sandeel fishing should not be overlooked. VPA and CPUE data suggest that abundance increased as the fishery grew. A negative correlation between sandeel recruitment and total stock size preceding spawning suggests that there is now resource competition (bottom-up control). Bioenergetics modelling indicates that predatory fish take far more sandeel than taken by the industrial fishery or wildlife. Effects of decreases in predatory fish stocks have been greater than increases in the take by seabirds and seals and by the fishery. Thus, overall, there appears to have been a reduction in mortality during the last 30 years. Changes in predatory fish abundances, especially mackerel and whiting, may influence sandeel stocks more than changes in industrial fishery, at least at the scale of the North Sea as a whole. These interactions imply that seabird and seal food supply in terms of sandeel may be strongly dependent on decisions regarding management of stocks of mackerel and gadoids. The overwhelming influence of predation on “food-fish” by predatory fish may be a feature of many marine food webs worldwide, where “fishing down the food web” has occurred, and this has clear management implications if wildlife and fisheries are to coexist.

Keywords: fishery management; conservation; Ammodytes marinus; industrial fishing; predator-prey interactions; harvesting; trophic transfer; top predator; bioenergetics

Journal Article.  0 words. 

Subjects: Environmental Science ; Marine and Estuarine Biology

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