|Utilization of discarded fish by scavenging seabirds behind whitefish trawlers in Shetland|
|Hudson, A.V.; Furness, R.W. (1988). Utilization of discarded fish by scavenging seabirds behind whitefish trawlers in Shetland. J. Zool. (1987) 215(1): 151-166. dx.doi.org/10.1111/j.1469-7998.1988.tb04890.x|
|In: Journal of Zoology (1987). Zoological Society of London: London. ISSN 0952-8369, more|
Marine birds; ANE, British Isles, Scotland, Shetland I. [gazetteer]; Marine
Although the availability of discarded fish from trawlers has been suggested as a cause of population increases of scavenging seabirds in the British Isles during this century, the study described here provides the first quantitative data on the utilization of discard fish by different seabird species. Around Shetland in summers 1984 and 1985, great black-backed gulls, gannets and great skuas obtained most discard fish. On average, larger scavenging species swallowed larger fish, and dropped less. The proportion of discards dropped increased with fish size. Haddock and whiting were mainly consumed but many gurnards and most flatfish were rejected by seabirds and allowed to sink. The large size of discards from Shetland trawlers puts smaller scavenging seabirds (herring and lesser black-backed gulls, great skuas) at a competitive disadvantage; great black-backed gulls and gannets exploit discards most effectively.