Foraging strategies of deep-sea fish

Abstract

The structure of the stomach contents of 33 species of fish caught at depths between 400 and 2900 m in the Rockall Trough is analysed for information on foraging strategies of individual species. One representative (a single) or several representatlves (a multiple ~ncidence) can occur in stomachs. The contents of stomachs range from 1 to about 200 individual prey ~tems. of a prey species These items can comprise singles, singles and a multiple incidence, or singles and CO-occurring multiple incidences. Relations between the numbers of items occurring as slngles or multiple incidences and the total number of items in the stomachs of the different species of fish were examined. An attempt is made to analyse the progressive accumulation of items in stomachs as they become fuller. Results suggest that fish such as the benthopelagic feeding macrourids are exploiting multi-species patches of prey. Four types of general feeding strategies appear to be present among the specles. Ten species are primarily opportunistic feeders that occasionally feed repetitively on single prey species. Five species are also opportunistic feeders but lock-on to a single prey species that they exploit repetitively fairly regularly. Four species feed opportunistically on single items but in addition feed repetitively on 1 or more preferred prey species. Six species combine opportunistic and repetitive feeding much more closely to exploit a wide variety of resources. Data on the remaining 8 of the 33 species were not adequate to define their feeding strategies.