Estuary, it produced only about half 

 the average harvests of white shrimp, 

 brown shrimp, and blue crab and less 

 than a tenth of the oysters during 

 1962-76 (National Marine Fisheries 

 Service 1962-1977a). The Colorado 

 River, in the eastern arm of the es- 

 tuary, provides 65 percent of the 

 gauged flow to the estuary and is the 

 principal source of fresh water. 

 This quantity is only half of the 

 Colorado River flow because the other 

 half has discharged directly to the 

 Gulf since 1936 when a man-made chan- 

 nel was cut through the Matagorda 

 Peninsula. Some historical records 

 (Moore 1907) suggest that a much 

 greater oyster production occurred 

 when the entire Colorado River flowed 

 to the bay and there were few up- 

 stream diversions. Other presenta- 

 tions at this symposium will address 

 efforts by numerous individuals, 

 agencies, environmental organiza- 

 tions, and fisherman organizations 

 to have the entire flow of the Colo- 

 rado River directed once again into 

 the estuary. This will provide more 

 fresh water, nutrients, detritus, 

 and sediments to support the estu- 

 ary's productivity. 



A recent draft report on this 

 estuary by the Texas Department of 

 Water Resources (1979c) indicated 

 that approximately the present an- 

 nual median flow would be needed to 

 maintain current fishery harvests. 

 In a study performed for the Corps 

 of Engineers, van Beek and Gagliano 

 (1980) concluded that two primary 

 biological effects would result from 

 rediversion of the Colorado River 

 into Matagorda Bay: (1) increase in 

 area of productive wetland and aqua- 

 tic habitat, and (2) decrease in the 

 average salinity coupled with period- 

 ic flushing with freshwater floods 

 from the river. Rediversion should 

 result in a major enhancement of 



fishery harvests because of these ef- 

 fects. The other major source of 

 freshwater inflows is the Lavaca-Na- 

 vidad river system, which drains into 

 the upper reaches of Lavaca Bay. In- 

 flows will be reduced when the Pal- 

 metto Bend reservoir on the Navidad 

 is completed and its yield signifi- 

 cantly utilized. 



Guadalupe (San Antonio) 



The Guadalupe (San Antonio) es- 

 tuary represents 11 percent of the 

 state's estuarine area, but provides 

 a somewhat higher percent of Texas 

 estuarine harvests of white shrimp, 

 brown shrimp, and blue crabs (Nation- 

 al Marine Fisheries Service 1962- 

 1977b). Parker (1955:210) noted in 

 1953, "During low-salinity years the 

 reefs were composed primarily of 

 Crassostrea virginica " (the Ameri- 

 can oyster) and, " Penaeus setiferus , 

 the commercial white shrimp, virtu- 

 ally disappeared from the bays with 

 the increase in salinity" (from 

 1948-1953). 



An extensive 33-month study by 

 the Texas Parks and Wildlife Depart- 

 ment concluded that an annual aver- 

 age inflow of 2.5 to 3.8 times es- 

 tuarine volume would provide opti- 

 mum conditions in this estuarine 

 system for shellfish production, 

 with emphasis on white shrimp. A 

 commercial shellfish production a- 

 bove 1.5 million pounds possibly 

 could be maintained with a minimum 

 annual inflow of 2.0 times 

 estuarine volume (Childress et al. 

 1975). A Texas Department of Water 

 Resources study (1979d) estimated 

 that annual flows comparable to the 

 current annual median inflows (3.3 

 times estuarine volume) would be 

 required to maintain the present an- 

 nual bay fishery harvests, which 



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