Cross-site comparisons of Gulf Sturgeon prey assemblages throughout the northern Gulf of Mexico reveal regional differences

摘要

Gulf Sturgeon, Acipenser oxyrinchus desotoi, is listed as threatened, with critical habitat designated throughout the northern Gulf of Mexico (GOM) to protect, in part, areas where feeding occurs. Because not all critical habitat appears to provide equivalent foraging value, reliably identifying areas of relatively high vs. low prey density coupled with appropriate sediment composition may provide important management considerations. Examination of existing benthic datasets (1980-2006) across the Gulf Sturgeon's range revealed potential prey assemblages differed geographically, with a dominance of amphipods on the northwest coast of Florida, lower overall potential prey densities in the north-central GOM, and relatively high gastropod and bivalve densities in Louisiana. Within sites, high prey densities frequently occurred where high Gulf Sturgeon activity levels previously were identified in telemetry studies, suggesting the historical benthic data sets provide information relevant to foraging habitat. Gulf Sturgeon prey assemblages were correlated with physical parameters at 11 of 14 sites examined and physical parameters included in these correlations differed between eastern and western regions. Gulf Sturgeon prey assemblages were typically correlated with depth and % sand where sand content was high, such as the eastern portion of the sturgeon's range, as well as parts of both Mississippi Sound and Chandeleur Sound. In contrast, depth, % TOC, and DO were associated with prey assemblages in areas with low sand content in Louisiana and Alabama. These regional results indicate that management approaches on spatial scales smaller than the northern GOM should be considered.