Competition between Fisheries and Seabird Communities

Abstract

Publisher Summary Seabird studies have been prominent in the development of general theories of animal population regulation. Many British seabird populations have increased in numbers during this century and some of these increases have been both rapid and prolonged. Such large population changes may suggest that density-dependent control of population is unimportant or may be taken as evidence that food supplies have improved. There has been a tendency to neglect seabird diets and feeding ecology, particularly outside the breeding season, and few biologists have succeeded in placing seabirds in context with the other components of marine ecosystems. Seabirds are generally the top predators in marine ecosystems, and as such are potential competitors with commercial fisheries. There have been demonstrable changes in ecosystem structure in many seas and oceans as a result of overfishing, as well as natural climatic or oceanographic fluctuations. This chapter discusses the evidence suggesting that seabirds are an important component of many marine ecosystems, in that they consume more than a trivial quantity of the production of lower trophic levels, and examine the changes in seabird abundance, which have taken place in many parts of the world, apparently as a response to alterations in lower trophic levels of the marine ecosystems. It then examines the evidence concerning ways in which seabird population dynamics may be affected by food quality or availability, and assess the likely influence of some current trends in the management of fisheries.