Coastal Sciences, Gulf Coast Research Laboratory
Ocean Science and Engineering
© 2020 National Shellfisheries Association. All rights reserved. The possibility that the economics of the oyster fishery impose a self-limitation on overharvesting has been proffered on occasion. The inefficiency of harvesting by the fishery has been evaluated and estimates of the exploitation rate permissible under conditions of maximum sustainable yield have been obtained in previous studies. The question becomes to what extent does the inefficiency of harvest interact with the economics of the fishery to compromise ready detection of overfishing? This study explores the possibility that the constraint of economics on the fishery occurs at oyster exploitation rates that are higher than maximum sustainable yield, leading ineluctably to overfishing if unconstrained and to the appearance of unduly limited fishing if properly constrained. A model is developed that simulates oyster harvesting by dredging. This model tracks vessel behavior and fishery performance in economic terms (CPUE) under varying stock densities and dredge efficiencies. Simulation results show that stock density and on-deck culling speed have the strongest effect on time required, profitability, and effectiveness of harvest, whereas dredge efficiency has a lesser influence. Evaluation of simulations shows that overfishing occurs at a stock density that provides near-optimal economic returns. The oyster fishery does not perceive a decline in the stock under sustainable conditions, as the on-deck processing capacity enables the catch rate to remain relatively stable until the stock declines well below sustainable levels. The consequence of setting fishing regulations such that a decline in catch is perceived is to assure routine and substantive overfishing, thereby creating a potential conflict between apparent and real sustainability. This conflict may explain the inability of state regulatory authorities to impose limitations consistent with long-term resource stability. The perception that a decline in the rate of catch should be observed under standard effort-based regulatory controls is a principal challenge that must be overcome if sustainability is to become normative in the U.S. oyster fishery.
Journal of Shellfish Research
(2020). The "Challenge" of Depletion: Why the Oyster Fishery is Not Self-Regulating. Journal of Shellfish Research, 39(2), 291-302.
Available at: https://aquila.usm.edu/fac_pubs/18244