Gulf flounder, continued 



Life Mode 



Eggs and larvae are planktonic. Postlarvae become 

 demersal after metamorphosis. Juveniles and adults 

 are demersal (Bond 1979). 



Habitat 



Ty pe: Eggs are marine and neritic. Larvae are marine 

 and neritic, becoming estuarine. Juveniles and adults 

 are estuarine and marine. Adults are neritic, and are 

 found offshore as far as the mid-continental shelf in 

 depths up to 50 m. They prefer shallow waters (<30 m) 

 of bays and the nearshore Gulf of Mexico (Ginsburg 

 1952, Miller 1964, Powell 1974, Stokes 1977, Benson 

 1982). It rarely enters areas with reduced salinities, 

 and never enters freshwater (Gilbert 1986). It is 

 considered probable that gulf flounder in excess of 2 or 

 3 years of age reside exclusively in the Gulf (Stokes 

 1977). 



Substrate : Gulf flounder typically occur over hard sand 

 bottoms. Juveniles have been reported in association 

 with seagrass beds (Ginsburg 1952, Reid 1954, 

 Springer and Woodburn 1960, Stokes 1977, Fischer 

 1978, Hoese and Moore 1977). 



Physical/Chemical Characteristics 

 Temperature: The reported range of temperatures 

 where the Gulf flounder occurs is 8.3° to 32.5° C (Reid 

 1 954, Springer and Woodburn 1 960, Wang and Raney 

 1971, Stokes 1977). 



Salinity: This fish ranges from the seawater zone to the 

 seaward end of the mixing zone of estuaries. It 

 reportedly prefers higher salinities (>20%o) (Gunter 

 1945, Powell and Schwartz 1977). Collections have 

 been reported from salinities ranging from 6 to 60%o 

 (Reid 1954, Simmons 1957, Springer and Woodburn 

 1960, Williams and Deubler 1968, Wang and Raney 

 1 971 , Topp and Hoff 1 972, Powell 1 974, Stokes 1 977, 

 Powell and Schwartz 1977). Williams and Deubler 

 (1 968) reported that postlarvae are found in estuarine 

 habitats at salinities >22% . In North Carolina, juveniles 

 were collected in salinities ranging from 6 to 35%o, but 

 the majority occurred above 20% o (Powell and Schwartz 

 1977). 



Turbidity: Stokes (1 977) stated that Gulf flounder were 

 not present in waters with turbidity greater than 65 

 Jackson Turbidity Units (JTU). 



Migrations and Movements : Adults migrate out of the 

 estuaries to neritic offshore waters during fall and 

 winterto spawn. Timing of the movement is associated 

 with the advent of falling water temperatures. Stokes 

 (1 977) reported that the Gulf flounder begins to move 

 offshore when water temperatures fall from 23° to 

 14.1 °C, and that peak immigration of juveniles coin- 



330 



