This report provides an overview of the ecological effects—both direct and indirect—of current fishing practices. Among the consequences are changes in the structure of marine habitats that ultimately influence the diversity, biomass, and productivity of the associated biota; removal of predators, which disrupts and truncates trophic relationships; and endangerment of marine mammals, sea turtles, some seabirds, and even some fish. Fishing can change the composition of ecological communities, which can lead to changes in the relationships among species in marine food webs. These changes can alter the structure, function, productivity, and resilience of marine ecosystems.
The repeated patterns of overfishing, bycatch mortality, and habitat damage are so transparent that additional science adds only incrementally to further documentation of immediate effect. Although it is always possible to find exceptions to these patterns, the weight of evidence overwhelmingly indicates that the unintended consequences of fishing on marine ecosystems are severe, dramatic, and in some cases irreversible.