Modeling Fish and Shellfish Distributions in the Mobile Bay Estuary, USA

Brenda Rashleigh 1, Mike Cyterski 1, Lisa Smith 2 and Janet Nestlerode 2

1 U.S. Environmental Protection Agency, Athens, Georgia
2 U.S. Environmental Protection Agency, Gulf Breeze, Florida

Estuaries in the Gulf of Mexico provide rich habitat for many fish and shellfish, including those that have been identified as economically and ecologically important. For the Mobile Bay estuary, we developed statistical models to relate distributions of individual species and species assemblages to two dozen water quality and habitat variables in a geo-referenced database. A hierarchical cluster analysis was performed on Mobile Bay fish and shellfish abundance data from 123 samples to identify groups of co-occurring species. Fifteen clusters were used subsequently in a discriminant analysis with water quality and habitat variables; a 65% success rate in classifying the fish assemblages was achieved. Next, habitat variables were used to develop predictive habitat models for individual species. Fish and shellfish responded most strongly to patterns of salinity, depth, substrate, and water chemistry. Results from this work could be used to guide restoration of degraded estuarine habitat, which is a key environmental goal of the National Estuary Program. Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy.

Modeling Fish and Shellfish Distributions in the Mobile Bay Estuary, USA

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