Impacts of Fishing Activities on Benthic Habitat and Carrying Capacity:Approaches to Assessing and Managing Risk
Michael J. Fogarty
Abstract. The need to consider the direct and indirect effects of fishing activities on the productivity of marine populations, communities, and ecosystems is now widely appreciated. Fishery management strategies have traditionally centered on controlling the direct effects of harvesting on the productivity of exploited stocks. Recognition of the need to consider the broader ecosystem effects of fishing has focused attention on management strategies also designed to preserve vulnerable habitats, conserve biodiversity, and protect ecosystem goods and services. Here, it is shown that if fishing activity simultaneously results in removal of target species and in habitat degradation affecting carrying capacity, fundamental changes in the shape of the production function result, and the corresponding biological reference points are altered relative to the case where fishing only results in removal of biomass. Further, the time scales of recovery (or indeed whether recovery is possible) from an over-exploited state may depend substantially on the recovery of habitat and benthic productivity. If these effects remain unrecognized, the risk to the population(s) and the ecosystem as a result of fishing are exacerbated. Managing risk in this context entails evaluating alternative hypotheses concerning the habitat effects of fishing and tailoring management approaches to the specific risks engendered by different fishing practices. Tactical management strategies available to address these risks include (1) overall effort controls, (2) changes in gear design or fishing practices, and (3) use of various forms of spatial management strategies including marine protected areas and regions zoned for the use of particular gear types only. A full evaluation of risk will involve assessment of additional stressors in relation to fishing-related impacts on marine ecosystems.