AN ECOLOGICAL STUDY OF GEORGIA COASTAL FISHES 



Michael D. Dahlberg^ 



ABSTRACT 



The distribution of fishes in relation to ecological factors was studied in a Georgia estuary 

 and adjoining beach and coastal plain creek waters to establish fundamental base lines 

 for the ecology of a relatively undisturbed section of the coast. The distributions of 168 

 fish species were related to nine recognizable habitats, temperature, and salinity. Length 

 frequencies and spawning seasons were determined for most of the trawled species that 

 contributed significantly to fish production in the estuary. 



Collecting by a variety of techniques permitted evaluations of types of life cycles, of 

 diversity in the various aquatic habitats, and of distribution patterns within the estuarine 

 complex and adjoining waters. Numbers of species collected in nine aquatic habitats 

 were as follows: beach - 114, lower reach of the estuary - 100, high marsh - 56, upper 

 and middle reaches - 61, oligohaline creek - 40, fresh water - 39, tidal canal - 22, low- 

 salinity tidal pool - 22, high-salinity tidal pool - 37. 



Estuaries are highly productive and support im- 

 portant sport and commercial fisheries. A ma- 

 jority of the nation's commercial finfish and 

 shellfish species and many coastal sport fishes 

 utilize the estuarine environment during at least 

 part of their life cycle. Estuaries are important 

 recreational areas, especially for fishing, partly 

 because of their proximity to civilization. Un- 

 fortunately, this proximity and lack of pollution 

 controls have resulted in mass degradation of 

 the nation's estuaries through pollution, filling, 

 and dredging. Pre-pollution studies are essen- 

 tial for the precise evaluation of the ecological 

 impact of stresses on estuaries. The normal 

 functioning of estuaries must be understood be- 

 fore scientists can evaluate the effects of var- 

 ious stresses on estuaries. There is an urgent 

 need to determine the significance of coastal ha- 

 bitats to the various life history stages of coastal 

 fishes. The central Georgia coast presents an 

 opportunity to study the ecology of fishes in a 

 relatively undisturbed estuary and establish 

 fundamental base lines for the detection and 

 evaluation of pollution. Aspects of fish ecology 

 that have been selected for examination include 



^ University of Georgia, Marine Institute, Sapelo Is- 

 land, GA 31327; present address: Virginia Institute 

 for Scientific Research, 6300 River Road, Richmond, VA 

 23229. 



(1) distribution of fishes in relation to recogniz- 

 able habitats, salinity, and temperature, (2) size 

 frequencies and spawning seasons of many 

 abundant species, (3) diversity of fishes in each 

 of nine habitats, and (4) types of life cycles. 



Except for the Brunswick and Savannah re- 

 -gions, Georgia estuaries are relatively free of 

 pollution. However, certain Golden Isles along 

 the Georgia coast are being considered for strip 

 mining for titanium and phosphate. A nuclear 

 power plant is under construction on the lower 

 Altamaha River. Recent developments in the 

 estuary studied herein include a kraft paper mill, 

 a shrimp culture farm that may not be completed, 

 and an interstate highway that may alter tidal 

 flushing. 



A complete picture of species distributions and 

 size in coastal waters can be obtained only if all 

 major habitat types are examined (Springer 

 and Woodburn, 1960) . Extensive trawling and 

 seining were undertaken to achieve this goal. 

 Comparisons with other studies are complicated 

 by the difference in types and numbers of hab- 

 itats sampled and differences in collecting meth- 

 ods. 



There has been little work on the ecology of 

 fishes of the U.S. Atlantic coast between Cape 

 Hatteras, N.C., and northern Florida. Tagatz 

 (1968) surveyed the fishes of St. Johns River, 



Manuscript accepted January 1972. 



FISHERY BULLETIN: VOL. 70, NO. 2, 1972. 



323 



