Strictly for the birds? On ecosystem services of forage fish

Abstract

Small pelagic fish like sardine, anchovy and herring feed on zooplankton and are in turn prey for fish higher up in the food chain. They are therefore expected to play a vital role in transfer of energy between levels in the food chain. Some stocks of small pelagics are extremely large and subject to very substantial fluctuations caused by environmental factors. They are also very vulnerable to exploitation due to schooling behavior and highly efficient fishing technology. Several such stocks crashed in the 20th century as a result of heavy exploitation and/or adverse environmental changes. The effect of four such stock crashes on other fisheries are reviewed and found to be limited or nonexistent. This puts into perspective a recent report from the Lenfest Foundation, which examines small pelagics and their role in the ecosystem and finds that certain sea bird populations have been severely affected by exploitation of small pelagics. The report recommends more conservative management of small pelagics to limit the effects on predators, but makes no effort to weigh this against the contribution of forage fish to food production.