Bluefish, continued 



uncommon in the eastern Gulf off of the Florida coast 

 (Ditty and Shaw 1995). Recreational catch data sug- 

 gest that bluefish are more common off of Louisiana 

 and Texas, and less common along the Florida Gulf 

 coast (Ditty and Shaw 1995). 



Life Mode 



Both eggs and larvae are pelagic and planktonic 

 (Lippson and Moran 1974, Norcross et al. 1977). 

 Juveniles and adults are pelagic and nektonic. This is 

 a migratory species in which both large juveniles and 

 adults school, but usually separately. Adults are diur- 

 nal, and are active all daylight hours (Pullen 1962, 

 Parker 1965, Olla et al. 1970, Olla and Studholme 

 1972, Hardy 1978, Bargeret al. 1978, Benson 1982). 

 Swimming speed increases at dawn and decreases 

 during the late afternoon and evening (Walford et al. 

 1978). 



Habitat 



Ty pe: This species inhabits temperate and warm tem- 

 perate zones, generally in continental shelf waters 

 (Wilk 1977). Eggs and larvae are found in continental 

 shelf waters, usually over depths <1 00m. Larvae move 

 inshore sometime during theirfirst growing season and 

 are occasionally found in the mouth of bays. They were 

 collected from water depths ranging from 34 to 183 m 

 in one study, with all but one captured in waters >49 m 

 deep (Moe 1972, Lippson and Moran 1974, Norcross 

 et al. 1974, Barger et al. 1978, Benson 1982). Eggs 

 and larvae are found in euhaline (marine) salinities 

 (Barger et al. 1978, Benson 1982). Juveniles have 

 been reported from both inshore and offshore areas in 

 clear and turbid waters. Inshore collections include 

 such habitats as along ocean beaches, lagoons, 

 sounds, bays, barrier island passes, estuaries, and 

 bayous. 



Juveniles are known to enter estuaries, and may 

 remain there for several months at a time on the U.S. 

 east coast (Juanes et al. 1993, McBride et al. 1993). 

 Movement into these areas may benefit survival and 

 growth due to shelter and food resources (Gunter 

 1945, Arnold et al. 1960, Pullen 1962, Zimmerman 

 1969, Perret et al. 1971, Franks et al. 1972, Norcross 

 et al. 1 974, Hardy 1 978, Benson 1 982). Early juveniles 

 (1 4.0-1 6.5 mm) can be found as far as 96 km offshore. 

 Juveniles are usually found above the thermocline, 

 with a reported depth range of 1 .1 to 26 m deep (Clark 

 et al. 1969, Zimmerman 1969, Franks et al. 1972, 

 Norcross etal. 1974, Hardy 1978). Juveniles have also 

 been collected considerable distances up rivers in New 

 England (Norcross et al. 1 974, Hardy 1 978). Salinities 

 from which juveniles are reported range from fresh to 

 euhaline (Gunter 1945, Pullen 1962, Parker 1965, 

 Perret et al. 1 971 , Franks et al. 1 972, Hardy 1 978). 



Adults have been captured in nearshore areas of 

 barrier islands and their passes, and along island 

 beaches on the Gulf side, but are not common in low- 

 salinity estuarine areas. Adults may move into or near 

 estuaries to feed (Simmons 1 957, Franks et al. 1 972, 

 Swingle 1977, Benson 1982). They prefer shallow 

 water, near dropoffs from shoal and banks (Shipp 

 1 986). However, they may occur in water as deep as 

 100 m (Lund 1961, Franks et al. 1972, Hardy 1978), 

 and during the spawning season, they have been 

 reported up to 1 48 km offshore in the Mid-Atlantic Bight 

 (Norcross et al. 1974). In Texas, they are sometimes 

 found in association with schools of gulf menhaden 

 (Breuer 1949). 



Substrate : Juveniles have been found over bottoms of 

 shell and sandy shell with hard packed mud (Pullen 

 1962, Zimmerman 1969). Bottom types for all life 

 stages are probably many and varied due to the pelagic 

 and wide ranging nature of this species. 



Physical/Chemical Characteristics : 

 Temperature - Eggs: In one laboratory study, eggs 

 fertilized in vitro were successfully incubated in a 

 temperature range of 18 to 22.2°C, with an average 

 temperature of 20.0°C until hatching (Deuel et al. 

 1966). Eggs in the wild occur from 18 to 26.3°C 

 (Norcross et al. 1974). 



Temperature - Larvae: In one study of 1 8 specimens, 

 larval bluefish were reported in the Gulf of Mexico over 

 a temperature range of 23.2 to 26.4°C (Barger et al. 

 1 978, Benson 1 982). Ditty and Shaw (1 995) collected 

 70 larval bluefish in the northern Gulf of Mexico at a 

 mean temperature of 24.6°C, with a range of 22.4 to 

 26.9°C. Minimum temperature has been suggested as 

 21 °C (Hardy 1978). 



Temperature - Juveniles: Juveniles have been re- 

 corded in temperatures from 1 4.8 to 31 .2°C in the Gulf 

 of Mexico (Gunter 1945, Pullen 1962, Perret et al. 



1971, Wang and Raney 1971, Franks et al. 1972, 

 Hardy 1978). Water temperatures below 10°C are 

 considered lethal for this life stage (Lund and Maltezos 

 1 970), but these temperatures generally don't occur in 

 the Gulf of Mexico. 



Temperature - Adults: The temperature range recorded 

 for adults is 1 8-21 .0°C (Deuel et al. 1 966, Franks et al. 



1972, Norcross et al. 1974). Swimming speed is 

 significantly affected by temperature with stressful 

 behavior noted below 1 1 .9°C and above 29.8°C (Olla 

 and Studholme 1971). Adults can survive tempera- 

 tures as low as 7.5°C temporarily (Lund and Maltezos 

 1970). 



205 



