Interactions Between Breeding Seabird and Pelagic Fish Populations in the Southern Benguela Region

Abstract

ABSTRACT: A bioenergetics model was used to estimate the quantity of pelagic fish eaten and the energy consumed by 3 species of breeding seabirds in the Saldanha Bay fishing ground in the Southern Benguela Region off the west coast of South Africa. The 3 species - jackass penguin Spheniscus demersus, Cape gannet Sula capensis, and Cape cormorant Phalacrocorax capensis -were estimated to consume a total of 16,500 t of fish yr-', of which 11,800 t were anchovy Engraulis capensis Gilchrist. This represented a total consumption of 1.3 X 108 Kj. Annual consumption of fish by the 3 seabird species was estimated to represent 30 % of the mean annual catch in the Saldanha Bay fishing ground, based on a mean commercial fishery landing of 55,000 t per year. This figure is similar to that estimated forfor several other oceans where breeding seabirds and a commercial fishery coexist.