Predation of whiting and haddock on sandeel: aggregative response, competition and diel periodicity
Abstract:The predation of haddock Melanogrammus aeglefinus and whiting Merlangius merlangus on sandeel Ammodytes marinus was investigated based on intensive sampling [performed with a bottom trawl (GOV) equipped with a small meshed codend cover; sediment samples were taken with a van Veen grab] in a restricted area of c. 15 × 20 nautical miles in the northern North Sea during a 5 day period in July 1996. The analysis of the spatial distribution of predators revealed a pronounced aggregation of whiting in the south‐west part of the area, where sandeel catches were also highest. This pattern was thought to be the result of an aggregative behaviour of whiting. The sandeel concentration most likely reflected a restricted patch of coarse sediment of the preferred grain size for sandeels to bury in. In haddock the aggregation was less obvious. Both predators fed almost exclusively on sandeel in the south‐west part of the area with haddock stomachs containing more sandeel than whiting stomachs. The stomach contents in both predators increased rapidly during the night, indicating that the predators were targeting burying sandeels. This would explain the competitive advantage of the benthivorous haddock.
Document Type: Regular Paper
Affiliations: 1: Institute of Hydrobiology and Fisheries Science, University of Hamburg, Olbersweg 24, D 22 767 Hamburg, Germany and 2: Federal Research Centre for Fisheries, Institute for Sea Fisheries, Palmaille 9, D 22 767 Hamburg, Germany
Publication date: 2004-05-01