Dew et al: Model for assessing populations of Crassostrea ariakensis in Chespeake Bay 



767 



tions are done in terms of energy, which then is converted 

 into population size. Because the available Suminoe oyster 

 data were demographic instead of bioenergetic, we felt a 

 demographic population dynamics model made defensible 

 use of available information. Additionally, the equations 

 of the time-dependent energy flow model included param- 

 eters such as filtration rates, respiration, assimilation, and 

 reproduction efficiency. These parameters have yet to be 

 determined for the Suminoe oyster. 



The scope of our model could be easily expanded to in- 

 vestigate more detailed scenarios and outputs. Economic 

 aspects could be modeled to examine cost and profit and 

 loss relationships for commercial production of triploid 

 Suminoe oyster under various assumptions. In addition, 

 the model could be adapted to a monthly instead of yearly 

 time step, allowing managers to examine effects of stock- 

 ing at different times of the year. The model could be made 

 more spatially explicit, allowing managers to examine the 

 probability of a population becoming self-sustaining over 

 a larger area encompassing multiple deployment sites. 

 Physical processes of water flow may have important ef- 

 fects on oyster recruitment. In our model, we assumed that 

 water flow mimicked that in the James River, Virginia, as 

 described in Mann and Evans (1998). Hence, our model is 

 most appropriate for ecosystems where, as in the James 

 River, larvae remain in the approximate area of their 

 production. Clearly, this would not be the case at all sites. 

 In sites where advection of larvae into or out of the area 

 is at issue, one or more terms would have to be added to 

 the model to account for such movement. Additional work 

 is needed to assess a wider range of management options 

 and potential risks. 



Acknowledgments 



This work was supported by the Virginia Sea Grant Col- 

 lege Consortium. We are also grateful for support and help 

 given by Gustavo Calvo, Patricia Flebbe, Rodger Mann, and 

 Alison Williams. 



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