Population Dynamics Variation of Blue Catfish during Its Introduction and Expansion in Virginia Tidal Rivers: A Bayesian Hierarchical Approach

Blue Catfish (BCF) was introduced as a trophy species into James, Rappahannock and York Rivers of Virginia since 1970s and 1980s. Their populations in the rivers have been found to expand rapidly into many tributaries in the Chesapeake Bay, and have recently been called as invasive species. Because of lacking a stock assessment model, fisheries management for this species becomes very problematic.  Understanding and modeling population dynamics of BCF during its expansion and adaptation to this new ecosystem becomes critically important for its management.  A Bayesian hierarchical approach was used to model the population dynamics of the BCF in James, Rappahannock and York Rivers.  BCF has been found to show differences in individual fish growths and population growth rates among these three rivers based on survey catch rates over time.  Based on available total catch of catfishes, catch composition of different catfishes and the BCF catch rates time series, a Bayesian hierarchical state-space time varying model was developed to consider the potential heterogeneity in population dynamics of BCF in these 3 rivers and the potential changes in population growth rate during its expansion.  Our population dynamics modeling is important for BCF fisheries management in the near future.