Historical Analysis of Species Biomass Distributions of Commercially and Recreationally Important Fish Species in Coastal Louisiana

The Louisiana deltaic ecosystem is experiencing dramatic changes, primarily as a result of leveeing the Mississippi River during the early parts of the 20^th century.  A long-studied consequence of anthropogenic containment of the river has been extensive habitat loss in the coastal ecosystem due to subsidence and sea level rise. Direct and indirect effects of anthopogenically-induced habitat loss on commercially and recreationally important fish populations have not been adequately addressed.  This study utilizes 40 years of fishery independent data to hind-cast historical distributions of some of the most abundant and economically important species in deltaic plain estuaries.  Data are analyzed and input into contour mapping software to visualize species abundance distributions through time and space.  Spatial and temporal analyses help elucidate patterns of abundance when used in concert with physical data such as salinity and changes in fish habitat (e.g., the ratio of marsh edge to open water).   Preliminary results suggest that recreationally important species, such as red drum (Sciaenops ocellatus) that prefer lower salinities in estuarine nursery areas, decreased in abundance in areas where saltwater has intruded well into the upper reaches of the estuary.  Long-term data sets, such as the one used in this study can reveal ecological patterns that can help fisheries managers determine the distribution and abundance of economically important species. Future analyses will help to determine if restoration scenarios proposed for Louisiana will help to mitigate some of the negative impacts on fish density due to land loss and other habitat changes.