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FISHERY-ORIENTED MODEL OF MARYLAND OYSTER POPULATIONS
Citation:
Jordan, S J. AND J. Vanisko. FISHERY-ORIENTED MODEL OF MARYLAND OYSTER POPULATIONS. Presented at National Shellfisheries Association, New Orleans, LA, April 13-17, 2003.
Description:
We used time series data to calibrate a model of oyster population dynamics for Maryland's Chesapeake Bay. Model parameters were fishing mortality, natural mortality, recruitment, and carrying capacity. We calibrated for the Maryland bay as a whole and separately for 3 salinity zones. Simulations indicated that a long-term declining trend in the Maryland bay-wide stock of harvestable oysters could be reversed by controlling fishing mortality and enhancing recruitment. For example, an exponential increase in stock size was predicted by simulating a 40% reduction in fishing mortality; initial losses to the fishery were more than compensated by large gains after a few years. In the low salinity zone, where the harvestable stock has been maintained largely by relaying seed oysters, recruitment rates are too low to support a significant population increase, but stocks in the medium and high salinity zones appear to have potential for recovery within 10-20 years. The model is sensitive to mortality and recruitment rates, but not to carrying capacity, which is much larger than current stock sizes. Measures of uncertainty for model predictions include (1) confidence limits for mean predicted trends, and (2) percentage of iterative simulations that satisfy specified criteria.