FISHERY BULLETIN: VOL. 70, NO. 2 



abundant species. A low-salinity record of 0.1%c 

 was obtained from Riceboro Creek. 



ORDER TETRAODONTIFORMES 



Three marine species (in three families) in 

 this order were represented mostly by small 

 numbers of juveniles. Nearly all specimens 

 were collected in the lower reach and beach hab- 

 itats. One planehead filefish (Monacanthus 

 hispidus) was recorded for a low salinity of 

 11.87ff. The planehead filefish was in the estuary 

 from April to September at 21.8° to 31.3°C. The 

 northern puffer {Sphoeroides maculatus) and 

 striped burrfish {Chilomycterus schoepfi) were 

 in the estuary from April to November or De- 

 cember when the temperature was reduced to 

 approximately 11° to 16°C. 



LIFE CYCLES OF ESTUARINE SPECIES 



Many fishes found in estuaries follow the ma- 

 rine-estuarine life cycle pattern described by 

 Gunter (1967). They spawn in the ocean and 

 the young enter the estuarine and beach waters 

 where the salinity is reduced. The estuary ap- 

 parently provides them with a nursery ground 

 that is rich in food and a refuge from certain 

 predators, diseases, and parasites that do not 

 thrive in the rigors of highly variable salinities 

 and temperatures. Young of coastal species 

 often have greater tolerance to reduced salinities 

 than adults (Gunter, 1961). Young Atlantic 

 menhaden even require low salinities for devel- 

 opment (June and Chamberlin, 1959). Gunter 

 (1967) noted: "The preponderant macroorga- 

 nisms, both in numbers of species and individu- 

 als, are mostly motile species which undergo the 

 general type of life history described above. In 

 southern waters these are the mullet (Mugil) , 

 menhaden, croakers (sciaenids), shrimp and 

 crabs. Vast numbers of these animals may be 

 found in estuaries at one time or another and in 

 general the very smallest sizes are found in the 

 lower salinities." Some species that spawn in 

 high-salinity waters but were represented pre- 

 dominantly by young in two low-salinity estu- 

 arine habitats (oligohaline creek and low-salini- 

 ty tidal pools) included the spot, striped mullet, 



hogchoker, southern flounder, ladyfish, tarpon, 

 and snook. The Atlantic menhaden, silver perch, 

 and Atlantic croaker were euryhaline and rep- 

 resented in the upper reach primarily by young. 



Since estuaries are being destroyed by pollu- 

 tion, dredging, and filling, it is important to rec- 

 ognize which species are found in estuaries as 

 adults or young. Dependence of the young of 

 marine species on the estuaries is the basis of 

 the nursery ground concept (Gunter, 1967). I 

 expand the nursery ground concept to include 

 all species that are commonly represented by 

 young (defined herein as sexually immature) 

 in estuaries, whether they were spawned in the 

 ocean, estuary, or fresh water. 



A total of 168 species is listed for coastal 

 waters (Table 2). The number of species re- 

 corded for the estuary is 136 when the numbers 

 of species found only in the freshwater habitat 

 (17) and only along the beach (15) are excluded. 

 The beach and estuary are treated as a single 

 complex here because of their similar fish species 

 compositions. The estuary and beach complex 

 functions as a nursery ground to various 

 degrees for 78 species. Some young sharks 

 and rays that were commonly caught by angling 

 (Dahlberg and Heard, 1969) are included in 

 the compilation. Two species that spawn in 

 fresh water, the anadromous American shad and 

 the white catfish, are also included. The family 

 Sciaenidae includes 13 species that have young 

 dependent on the rich estuarine waters. These 

 sciaenids are the most important group of sport 

 fishes on the Georgia coast and they are poten- 

 tially important commercial fishes. Atlantic 

 menhaden that are reared in the estuaries are 

 caught off'shore in large numbers with purse 

 seines. Vitally important in the food chain are 

 forage species such as the bay anchovy, Atlantic 

 silverside, and rough silverside. 



Some organisms that are indigenous to bay or 

 estuarine waters, or at least normally complete 

 their life cycle in these waters, include certain 

 "copepods and planktonic species," several spe- 

 cies of molluscs including the American oyster, 

 certain gobioid and cyprinodontid fishes, and a 

 palaemonid shrimp (Gunter, 1967). I have not 

 found fish species that are restricted by salinity 

 tolerances to estuarine waters throughout their 



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