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Seasonal variation in the importance of pelagic fish in the diet of piscivorous fish in the Moray Firth, NE Scotland: a response to variation in prey abundance?

Seasonal variation in the importance of pelagic fish in the diet of piscivorous fish in the Moray... Species-ranked frequency distributions (k-dominance curves) indicated that the three pelagic fish species, herring, sprat and sandeel, contributed between 37% and 86% of the total fish biomass of the Moray Firth in June 1992, September/October 1993 and January 1994. The assemblage was dominated by the six most abundant species which accounted for 96% of the fish assemblage biomass in all three surveys. Two piscivorous fish species, whiting and haddock, were sufficiently abundant to have an impact on the pelagic fish prey resource. The percentage by weight of fish in the diets of both whiting and haddock increased with increasing predator length. Over 60% of the diet of whiting greater than 12 cm in length consisted of fish and little seasonal variation in this fraction was apparent. The percentage of fish in the diet of haddock was much lower and showed considerable seasonal variation. It exceeded 50% only in haddock of over 30 cm length, and only in June 1992 and January 1994. The piscivorous fraction of the whiting population biomass varied between 55% in September/October 1993 and 99% in June 1992. Only in June 1992 were haddock considered to be a serious predator of pelagic fish in the Moray Firth when 40% of the haddock biomass could be considered to be mainly piscivorous. The species composition of the fish fraction of the diets of both whiting and haddock showed considerable seasonal variation. For both predators it consisted almost exclusively of sandeels in June 1992 when the fish assemblage was dominated by sandeels. At other times, when sandeels were much less abundant in the water column and clupeids and gadoids more common, sprats were taken by the smaller whiting and haddock and small whiting by the larger predators. This difference in diet was attributed to larger predators being able to cope with larger prey. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png ICES Journal of Marine Science Oxford University Press

Seasonal variation in the importance of pelagic fish in the diet of piscivorous fish in the Moray Firth, NE Scotland: a response to variation in prey abundance?

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References (38)

Publisher
Oxford University Press
Copyright
© Published by Oxford University Press.
ISSN
1054-3139
eISSN
1095-9289
DOI
10.1006/jmsc.1997.0258
Publisher site
See Article on Publisher Site

Abstract

Species-ranked frequency distributions (k-dominance curves) indicated that the three pelagic fish species, herring, sprat and sandeel, contributed between 37% and 86% of the total fish biomass of the Moray Firth in June 1992, September/October 1993 and January 1994. The assemblage was dominated by the six most abundant species which accounted for 96% of the fish assemblage biomass in all three surveys. Two piscivorous fish species, whiting and haddock, were sufficiently abundant to have an impact on the pelagic fish prey resource. The percentage by weight of fish in the diets of both whiting and haddock increased with increasing predator length. Over 60% of the diet of whiting greater than 12 cm in length consisted of fish and little seasonal variation in this fraction was apparent. The percentage of fish in the diet of haddock was much lower and showed considerable seasonal variation. It exceeded 50% only in haddock of over 30 cm length, and only in June 1992 and January 1994. The piscivorous fraction of the whiting population biomass varied between 55% in September/October 1993 and 99% in June 1992. Only in June 1992 were haddock considered to be a serious predator of pelagic fish in the Moray Firth when 40% of the haddock biomass could be considered to be mainly piscivorous. The species composition of the fish fraction of the diets of both whiting and haddock showed considerable seasonal variation. For both predators it consisted almost exclusively of sandeels in June 1992 when the fish assemblage was dominated by sandeels. At other times, when sandeels were much less abundant in the water column and clupeids and gadoids more common, sprats were taken by the smaller whiting and haddock and small whiting by the larger predators. This difference in diet was attributed to larger predators being able to cope with larger prey.

Journal

ICES Journal of Marine Science – Oxford University Press

Published: Feb 1, 1998

Keywords: whiting haddock seasonal variation predator–prey relationships pelagic fish resource prey abundance

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