MEPS 299:257-268 (2005)  -  doi:10.3354/meps299257

ABSTRACT: The spatial and temporal structure of predator–prey relationships in the Celtic Sea was investigated for 4 commercially important predator species (cod Gadus morhua, hake Merluccius merluccius, megrim Lepidorhombus whiffiagonis, and whiting Merlangius merlangus) using stomach-content and bottom-trawl survey data for the period 1982 to 1995. Blue whiting Micromesistius poutassou were consumed more often during the summer months, whereas mackerel Scomber scombrus and Trisopterus spp. (poor cod T. minutus, Norway pout T. esmarkii, and bib T. luscus) were found more often in predator stomachs during the winter half-year. On a spatial scale, blue whiting was consumed over the shelf edge, in accordance with their higher densities in the environment, while mackerel, horse mackerel Trachurus trachurus and Trisopterus spp. were eaten more often on the continental shelf, again in agreement with their depth-related density-distribution patterns. The spatial distribution of whiting closely matched that of a key prey, Trisopterus spp. This might indicate an ‘aggregative response’ by the predator. The results of this study suggest spatial and seasonal prey-switching behaviour by cod, hake and whiting. Overall, the Celtic Sea fish community is characterised by opportunistic predators and general independence between predator and prey distributions. Interspecific predator interactions are reduced by size-, space- and time-dependent feeding behaviours.

KEY WORDS: Diet · Stomach contents · Preference · Celtic Sea · Season · Spatial distribution