World Conference on Natural Resource Modeling

Using Integral-Projection Models to Understand Oyster Demography and Management

High Country Conference Center

Oysters species are an important resource, both ecologically and economically. Yet, overfishing and habitat degradation have led to the loss of approximately 85% of oyster reefs worldwide. To best restore and manage these damaged populations, it is necessary to understand factors that influence population demography. Here, I use an age- and size-structured integral-projection model to study demographic patterns and management of the Pacific oyster, Crassostrea gigas. Model selection shows that incorporating age structure, in addition to size structure, is essential to capture important population patterns in this system. An elasticity analysis shows that population growth rate is most sensitive to changes in the survival of the largest and smallest individuals. This analysis indicates a slot limit (i.e. imposing both a maximum and minimum size limit on harvesting) could be an effective management strategy. I will describe how patterns in stable age and size distributions differ between populations that are increasing and decreasing in size, and how these patterns can be used to determine population status and restoration success. Finally, I discuss how the model can be extended to account for positive and negative feedbacks, as well as non-local recruitment, and how these additional biological complexities influence the dynamics and management of Pacific oyster populations.