
EPA Science Advisory Board	Background Information

Document Name	Louisiana estuarine and coastal fisheries and habitats: Perspectives from a fish's eye view
Document Author	Chesney, Edward J. Baltz, Donald M. Thomas, R.G.
Short Description	Ecological Applications, 10, 350-366
Category	Subgroup 1: Characterization of the Cause(s) of Hypoxia
Publication Year	2000

Text:

Abstract: Stimulated by nutrients from the Mississippi River, the vast coastal wetlands of the river's past and present deltas interface with the Gulf of Mexico to form a complex and prolific marine ecosystem. This highly productive system has yielded annual fishery landings of >453.6 x 10(6) kg (1 billion pounds) since 1969. The Louisiana ecosystem has been heavily exploited and significantly altered over the years to meet the demands for coastal development, seafood production, navigation, oil exploration, flood control, and other social, economic, and industrial activities. While not all impacts can be viewed as detrimental to fisheries or their habitat, some of these habitat impacts have contributed to significant ecological problems such as saltwater intrusion, loss of coastal wetlands, and development of vast area of hypoxia along the coast. Management strategies to deal with some of these problems propose directed manipulations of the coastal environments to stop or reduce rates of degradation. Over the past 46 years, fisheries yields from Louisiana waters have remained strong. Although quantitative data are lacking to examine more than a few decades of environmental changes, an analysis of fishery-independent trends for selected inshore species of nekton over a recent 21-yr period suggests that many species have been remarkably resilient to significant changes in their habitats and pressures from exploitation. Over a longer period (60 yr), more significant changes to inshore demersal trawl assemblages are apparent, but data are lacking to conclusively identify their causes or quantitatively document the magnitude of change. We review some of the major changes that have occurred in habitat believed to be essential to fishes and review other factors likely to be significant in structuring fish populations. Given the significant number of environmental impacts affecting the system, we also discuss potential reasons why more dramatic changes in nearshore and estuarine fish populations of coastal Louisiana are not apparent.