WETLAND LOSSES AND COASTAL FISHERIES: 

 AN ENIGMATIC AND ECONOMICALLY SIGNIFICANT DEPENDENCY 



R. Eugene Turner 



Center for Wetland Resources 



Louisiana State University 



Baton Rouge, LA 70803 



ABSTRACT 



Louisiana's coastal fishing industry landings are limited by the area of coastal 

 wetlands, not open water. The relationship is not sufficiently understood, but is 

 demonstrable through the life history patterns of all the commercially important species, 

 organism density in the vicinity of altered and natural wetland-water edges, experiments 

 in predation, and correlation analysis of landings data and wetland quantity and quality. 

 The management implications are that wetland area should be conserved in order to 

 maximize for the largest potential fisheries yields. The impact of previous wetland 

 losses are not well documented because of lack of good landings data that accounts for 

 both year-to-year environmental influences and a changing fishing effort. At a projected 

 1% wetland loss rate over the next 20 years, the commerical fishing industry will 

 experience a potential one billion dollar loss spread throughout the industry (exclusive of 

 the recreational value). Thus with a mere 10% reduction in the present loss rates, the 

 annual savings would be 5 million dollars. 



CORRELATION OF FISHERIES AND WETLANDS 



Across the broad geographic perspective of coastal environments it seems quite 

 clear that where wetlands and estuaries are large in area there are likely to be 

 substantial fishing industries nearby. To be sure, many fishing operations are nowhere 

 near wetlands, for example, the tuna and anchovy fisheries; but it is generally true that 

 if one can find a good-sized coastal wetland-estuary on the map and a suitable harbour 

 nearby that there is commerce in locally-caught fish and invertebrates. 



This correlation is easily shown with species such as penaeid shrimp whose 

 worldwide price is stable and high. Within an area, such as Louisiana, coastal wetland 

 area is directly correlated with the commerical landings of shrimp caught in inshore 

 waters (Figure I). Since the annual inshore catch is a fairly uniform percentage of the 

 total annual catch, the relationship is true for all landings vs. wetland area in Louisiana. 

 Worldwide, the weight caught per area wetland does vary within the geographic limits of 

 distribution of penaeids (Figure 2). We might show similar graphs for blue crab landings 

 (Turner and West, unpublished) or, if we had the landings data, for many species whose 

 life history involved a period of migration between coastal wetlands and open water. The 

 relationship between landings and open water, in contrast, is not a statistically 

 significant one, though it appears to be negative (Turner 1977). Furthermore, for shrimp, 

 at least, it is also true that the species of shrimp landed is directly related to the kinds 

 of vegetation present in the estuary. Brown shrimp in Louisiana, for example, are 



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