Oyster Reef Restoration as a Fisheries Management Tool

Abstract

Global declines in fish stocks over the past several decades have been caused by a combination of factors, including overfishing, habitat destruction, and water quality degradation. Despite the complexity of the problem, fisheries management traditionally focuses on effort reductions for individual fish stocks to rebuild populations. This single species management approach is often unsuccessful. Habitat restoration, however, is rarely included in management strategies and few studies have addressed the effectiveness of habitat restoration as a fisheries management tool. In the coastal southeast United States, the eastern oyster, Crassostrea virginica is an economically and ecologically important species. Oysters act as ecosystem engineers by building structurally dynamic reefs, providing habitat, cycling nutrients, and filtering water, thereby increasing water clarity. Oyster population declines have motivated state agencies, academic institutions, and local communities to initiate oyster reef habitat restoration projects. In addition to augmenting oyster populations, the restored reefs also provide essential habitat for a variety of economically and ecologically important fish and shellfish including black sea bass (Centropristis striata), gag grouper (Mycteroperca microlepis), sheepshead (Archosargus probatocephalus), gray snapper (Lutjanus griseus), and stone crab (Menippe mercenaria). The potential for restored oyster reefs to enhance the abundance and population growth rate of reef associated fish, and thereby offset catch reduction, has not been fully examined. This research assessed the biological and economic effectiveness of oyster restoration as a fisheries management tool for black sea bass. We hypothesize that: (H1) population growth rate of black sea bass will increase with increasing oyster reef area; and (H2) that the extent of oyster reef necessary to reach a stable population growth rate for black sea bass would be greater than the current area of restored reef in the Southeast United States. We used a computer simulation model to examine the black sea bass population growth rate response to oyster reef restoration, and to assess the economic costs and benefits of oyster reef restoration, fishing mortality reduction, and management inaction. The population growth rate of black sea bass increased with increasing oyster reef area; a total of 52.166 km2 of oyster reef was necessary to stabilize the population growth rate of black sea bass and thereby offset fishing mortality reduction to the fishery. When the economic benefits of black sea bass, gag grouper, gray snapper, sheepshead and stone crab recreational and commercial fishing were included, oyster reef restoration was the most economically effective management option evaluated compared to fishing mortality reduction or management inactions. These results suggest that the habitat restoration is an economically effective, holistic management option for rebuilding fish populations.