The Spatial Dynamics of Blue Crab in Chesapeake Bay
Blue crabs in the Chesapeake Bay have been subject to immense harvesting pressure by commercial and recreational fishers. There is compelling evidence that this pressure has been impacting crab populations throughout the Bay. For example, overall abundance of all age groups is down, and average size is decreasing. Consequently, reproductive potential may be compromised because of reduced sizes of males and lower numbers of mature females. Most stakeholders in Maryland and Virginia recognize the need for a program of sustainable management that is based on a scientific understanding of blue crab growth and behavior. Surprisingly, very little is known regarding blue crab growth and longevity, information critical to the development of predictive models linking crab population dynamics to fishing pressure and habitat. Traditional tagging methods to make such assessments in other fisheries do not work, because crabs grow by molting their shells and thus discard mechanical tags. On the other hand, rearing crabs in the laboratory cannot realistically simulate growth under different environmental conditions with sufficient accuracy to give reliable growth data. In this project, Thomas Miller will maintain crabs in cages in widely dispersed locations throughout the Bay over the course of two growth cycles in order to determine differences in growth attributable to habitat. Using these basic data, he will then develop mathematical models of blue crab growth that should enable resource managers to predict the implications of various strategies such as habitat conservation, protected areas or gear restrictions for maximizing harvests and sustaining populations.
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Thomas J. Miller
Chesapeake Biological Laboratory
University of Maryland Center for Environmental Science
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