Summary : Table 3.26 summarizes, by basin, the 

 estimated 1973 value of the commercial fish and fur 

 industry in the Chenier Plain. The value of the com- 

 bined industries is approximately $12 million. About 

 73% of this is the estuarine-dependent fishery, most of 

 the remainder is the fur industry. Because of its exten- 

 sive estuarine-dependent fishery, the Calcasieu Basin 

 supports the largest combined industry. Despite their 

 size, the Sabine and Mermentau basins have industries 

 that are not as valuable. The Mermentau Basin has no 

 significant estuarine-dependent offshore fishery, and 

 in the Sabine Basin, man's activities have resulted in 

 serious fishery decline. 



Trapping and Commercial Fisheries Activities that 

 Affect the Environment. The major ecological impact 

 of trapping and commercial fisheries is the direct har- 

 vest pressure on the resource. In addition to the har- 

 vest of fish and mammals, there is the immense loss 

 of the small fishes and shellfishes trapped in the trawls 

 along with the harvested shrimp. It has been estimated 

 that shrimp comprise only 5 to 32% of most trawl 

 catches on a weight basis (Klima 1976). The non- 

 commercial species are usually returned to the water, 

 but few survive, and most become part of the detritus 

 food base of the estuarine system prematurely. Ap- 

 parently there have been no investigations into the ef- 

 fect of this loss of small fishes and shellfishes on estu- 

 arine ecosystem dynamics. In areas of intensive shrimp 



fishing, trawling could influence the trophic structure 

 because it would tend to favor omnivorous feeders 

 over top carnivores. Trawls also re-suspend bottom 

 sediments and nutrients, increasing water turbidity. 

 This increased turbidity of estuarine and nearshorc 

 Gulf waters is evident during periods of intensive trawl- 

 ing. 



Seafood processing plants produce detrimental 

 discharges, but with a few exceptions these seem to 

 be minor. Discharges from menhaden processing plants 

 south of Calcasieu lake near Cameron, Louisiana, con- 

 tributed significantly to the high colifonn counts that 

 caused closure of the oyster beds in the lake late each 

 summer. 



Construction of docks and other facilities for the 

 industry produces local ecological impacts. Canals 

 significantly influence the inshore hydrologic flow. 

 The large, deep channels in the Chenier Plain were 

 constnicted primarily for ocean-going freigliters and 

 tankers, but many of the smaller navigation channels 

 are used extensively by the commercial fishing fleet. 

 Pirogue ditches constructed by trappers can, in hy- 

 drologically critical places, erode rapidly into major 

 waterways (Davis 1973). There are about 3,400 km 

 (2,100 mi) of navigation channels in the Chenier Plain 

 (table 3.27). 



Table 3.26. Estimated value (S x 1000) of commercial fishes, shellfishes, and the 

 fur industry in the Chenier Plain (1973)*. 



Summarized from tables 3.17, 3.22. and 3.25. 



46 



