CHAPTER 2. USE OF THE ESTUARINE ZONE 



The predominant uses of any particular estuarine area depend on 

 historical and economic development, population pressures, and the 

 kinds of natural resources available for exploitation. The socio- 

 economic environment of the estuarine zone is the direct result of the 

 value of the estuarine zone as a means of sustenance, a place to live 

 and work, a source of enjoyment, and a means of transportation. This 

 chapter describes that environment in terms of how the biophysical 

 environment is exploited to serve man's needs and shows conceptually 

 how valuable it is to his society (IV-2-1) . 



The major values of the estuarine zone to society form the framework 

 for discusing the relationships of individual uses, their compatibil- 

 ity with other uses, and the physical modification that has taken place 

 to support these uses. 



Section 1. Sustenance: Use as a Fish and Wildlife Habitat 



FISH 



Estuarine dependence is a convenient term for describing a nor- 

 mally complex biological interrelationship between the estuarine en- 

 vironment and an aquatic organism. This dependence includes a vast 

 spectrum of biological relationships. Practically all of the sports fish 

 species are dependent upon the estuarine zone for one or more phases 

 of their life development, and approximately 65 percent of all commer- 

 cial fish species are estuarine-dependent. The discussion in chapter 1 

 concerning life in the estuarine zone described the nature of estuarine 

 dependence and gave examples of several estuarine-dependent species 

 important to human society. 



Many fish species live their entire lives in the estuarine zone and are 

 well-adapted to this type of environment. The oyster, for example, has 

 lived in the estuary for millions of years, as evidenced by the huge 

 deposits of shell on the bottoms of bays. The shallow water, salty 

 substrate, and intermediate salinities are ideal for oyster culture. 



Other species may use the estuary only as a passage zone on their 

 way to freshwater streams or to the open ocean. However, in doing so, 

 they also utilize the high production of food that is characteristic of 

 estuaries. Even some continental shelf species, such as bluefish, and 

 most marine predators (including tuna), can be considered depend- 

 ent upon the estuary as an ultimate source of most of their food. 



The economically important fish species are those sought by either 

 the sports fisherman or the commercial fisherman ; however, the sports 

 fishes are usually taken by hook or with hand-held equipment. Table 

 IV.2.1 lists some of the more important estuarine-dependent species 

 of sports and commercial fish and shellfish. It also shows the type of 

 dependency of each. 



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