southern oyster drill ( Thais 

 haemastoma) onto productive oyster 

 reefs (Pollard 1973) and conversion 

 of fresher marsh vegetation to more 

 saline types. 



FISH AND WILDLIFE 



IMPLICATIONS OF 



WETLAND DETERIORATION 



FISHERIES 



The marshes of the LCR are ex- 

 tremely important to the maintenance 

 of its estuarine-dependent sport 

 and commercial fisheries. These wet- 

 lands produce vast amounts of organic 

 detritus, an important trophic com- 

 ponent of estuarine fish and shell- 

 fish productivity (Darnell 1961; Odom 

 et al. 1973). The marshes and asso- 

 ciated shallow waters of the LCR 

 are also important as nursery habitat 

 for many estuarine-dependent species. 

 This importance has been documented 

 by numerous authors, such as Herke 

 (1971), White and Boudreaux (1977), 

 Rogers (1979), and Chambers (1980). 

 There is growing evidence that the 

 amount of marsh is the most important 

 factor influencing estuarine-depend- 

 ent fishery production. Turner 

 (1979) reported that Louisiana's com- 

 mercial inshore shrimp catch is 

 directly proportional to the area of 

 intertidal vegetation, and that the 

 area of estuarine water does not seem 

 to be directly associated with shrimp 

 yields. He further noted that the 

 loss of wetlands in Louisiana has a 

 direct negative effect on fisheries. 

 Although the effects are masked by 

 large annual variations in yield, 

 wetland losses in the LCR reported by 



Craig et al. (1979) are equivalent 

 to 6.31 million pounds (2.86 million 

 kg) of shrimp harvest "lost" over the 

 past 20 years (Turner 1979). Lindall 

 et al. (1972) presented evidence 

 that shrimp and menhaden are being 

 harvested at or near maximum sus- 

 tainable yield. These species 

 accounted for nearly 99 percent of 

 the total volume of Louisiana's 

 commercial fish and shellfish land- 

 ings in 1976 (Plaisance 1977). Fur- 

 ther evidence that this is occuring 

 was presented by Harris (1973), who 

 noted that any substantial decreases 

 in marsh habitat will result in de- 

 creased estuarine-dependent fishery 

 production. An analysis of the de- 

 pendence of menhaden catch on wet- 

 lands in the LCR was conducted by 

 Cavit (1979). The findings of this 

 analysis suggest that menhaden yields 

 are greatest in those LCR estuarine 

 basins having the highest ratio of 

 marsh to open water. Based on the 

 evidence cited above, continued wet- 

 land loss in the LCR could lead to 

 serious declines in its estuarine- 

 dependent fishery. 



WILDLIFE 



Wildlife dependent on the LCR 

 marshes face serious habitat de- 

 clines as a result of future land 

 loss and saltwater intrusion. Losses 

 of fresh to intermediate marsh 

 (Chabreck 1972) or conversion of 

 these wetlands to more saline types 

 will adversely affect migratory 

 puddle ducks, as relative abundance 

 of these waterfowl in the LCR is 

 highest in these marsh types 

 (Palmisano 1973). Based on rather 

 conservative projections of declines 

 in habitat quality and abundance in 

 the LCR, it has been estimated that 

 demand for waterfowl hunting will 

 exceed available supply by 454,000 

 man-days by the year 2020 (U.S. Fish 



392 



