Modeling oyster populations: The effect of density and food supply on production

A time-dependent model has been developed to assess the response of oyster populations to environmental variables and the importance of population density in optimizing yield under varying climatic and hydrologic conditions. Food supply in a typical Gulf of Mexico bay, Galveston Bay, would appear to be just adequate in most years to maintain a healthy, productive oyster population. Any decline in food supply, by reduced food content, lower current velocity, lower temperature or increased population density, dramatically reduces yield and can eliminate reproductive capacity. The effect of temperature on filtration rate exerts an overriding influence, establishing, much more so than respiration, the energy balance of the organism, whether or not the population grows and reproduces, and to what extent current velocity and food supply affect productivity. The effect of decreased food supply, for any reason, is felt more strongly at higher latitudes. Large adult oysters probably have a negative energy balance during the winter in colder climes, except under the most favorable of food supply conditions. By contrast, higher temperatures at lower latitudes reduces somatic growth and, consequently, yield because more of the yearly net productivity is expended in reproduction