A Prey-Based Habitat Model to Inform Recovery Actions for Atlantic Sturgeon in Delaware Estuary

Recovery of Atlantic Sturgeon (Acipenser oxyrinchus oxyrinchus) will likely requirea better understanding of the physical and biological factors that drive habitat utilization at critical life stages.  Recent collaborative research in the Delaware River Estuary has produced spatial datasets of the biotic and abiotic composition of its benthos which can be used to better understand the drivers of sturgeon distribution.  In this study, we examine the importance of benthic invertebrate composition in determining concentration areas of late-stage juvenile sturgeon.  We created benthic faunal maps through a two-stage process. Using benthic invertebrate samples (n=234) stratified by salinity and sediment type, we defined invertebrate communities using cluster analysis.  We then determined the environmental thresholds (bathymetry, salinity, sediment type) that predicted the distribution of species clusters using classification and regression trees (CART) to yield a seamless map of benthic habitats which represent biologically-relevant environmental thresholds.  In this first phase of our work, we examine the relationship between juvenile sturgeon distribution and the distribution of benthic habitat types. Our ultimate goal is to develop a prey-based habitat model that can inform recovery actions for Atlantic Sturgeon in the estuary.  Upon development we hope that a more generalized form of the model may be suitable recovery actions for other sturgeon species.