Spotted seatrout, continued 



low marsh edges of small, saline water bodies in 

 Spartina altemiflora dominated areas (Peterson 1 986, 

 McMichael and Peters 1989, Chester and Thayer 

 1990). Individuals have also been found around oil 

 drilling platforms in the nearshore area (Stanley and 

 Wilson 1990). Juveniles and adults can occur in a 

 variety of estuarine habitats including seagrass beds, 

 mangrove-lined depressions, and in relatively deep 

 basins, tidal river mouths, channels and canals (Mok 

 and Gilmore 1983, Van Hoose 1987, Thayer et al. 

 1988, Chester and Thayer 1990, Killam et al. 1992). 

 Juveniles remain in submerged vegetation during sum- 

 mer, but may move to deeper water during the winter 

 months when water temperatures drop. Adults also 

 occur in the surf zones of barrier islands, particularly in 

 fall months (Perry 1970). 



Substrate : The substrate for larvae is highly variable. 

 Vetter (1977) states larvae are dependent on grass 

 beds, while Benson (1982) indicates that the deep 

 channels near grass beds may serve as their initial 

 habitat ratherthan algae and muddy sand (Tabb 1 961 ), 

 prior to movement into the grass bed as juveniles. In 

 Louisiana, where inshore salinities can be fairly low 

 due to the influence of the Mississippi River, nursery 

 habitat is probably higher salinity lower bays and the 

 nearshore Gulf of Mexico (Herke et al. 1984). Juve- 

 niles and adults are generally associated with 

 seagrasses, particularly Halodule and Thalassia, but 

 they are also common over sand, sand-mud, or me- 

 dium to soft, mud-detritus substrates, shallow muddy 

 areas, oil platforms and shell reefs (Benson 1982, 

 Peterson 1986, Rutherford et al. 1989a, McMichael 

 and Peters 1 989, Chester and Thayer 1 990, Killam et 

 al. 1992). 



Physical/Chemical Characteristics : 

 Temperature: Spotted seatrout appear to have a high 

 capacity for metabolic compensation for dealing with 

 the wide extremes in temperature that occur in the 

 estuarine habitats that they exploit on a year-round 

 basis (Vetter 1982). 



Temperature - Eggs: Eggs and yolk sac larvae have an 

 optimal temperature of 28°C, but have been hatched 

 experimentally at 32°C (Taniguchi 1980, Gray and 

 Colura 1 988). However, complete survival is expected 

 between 23. 1 ° and 32.7°. Eggs incubated at 20°C had 

 a lower mean hatch rate (Gray and Colura 1988). 



Temperature - Larvae and Juveniles: Larvae and juve- 

 niles have been collected in temperatures of 5° to 36°C 

 (Wang and Raney 1971, Perret et al. 1980, Benson 

 1 982, Rutherford et al. 1 989a, Killam et al. 1 992); their 

 preferred temperatures range from 20° to 30°C (Arnold 

 etal. 1976). 



Temperature - Adults: Adults prefer temperatures from 

 15° to 27°C, and may move seaward if estuarine 

 temperatures become extreme (Mahood 1974). 

 Simmons (1957) reported active feeding and move- 

 ment between 4° to 33°C with gradual acclimation; 

 however, sudden drops in temperature can result in 

 mass mortality (Gunter 1 941 , Moore 1 976). Tempera- 

 tures for spawning range from 20° to 30°C (Benson 

 1982). 



Salinity - Eggs: The highest hatch rates for experimen- 

 tally incubated eggs have been reported to occur at 1 5 

 to 25% and 1 9 to 38%o at 28°C (Shepard 1986, Gray 

 and Colura 1988), and it is suspected that in lower 

 salinities in the wild, survival may be reduced (Tabb 

 1966). The optimum salinity for eggs has been re- 

 ported to be 28.1%o (Killam et al. 1992). These eggs 

 had a significantly lower hatch rate at 5%o and all eggs 

 died at any temperature when the salinity was 45%o. 

 Eggs at 5%° would also sink to the bottom, which would 

 probably increase mortality in the wild. A critical 

 minimum (0% o ) and a critical maximum (50%o) has been 

 determined that corresponds to 0% embryo survival at 

 28°C (Shepard 1986). Salinity acclimation of parents 

 may also affect salinity tolerance of eggs (Gray and 

 Colura 1988). 



Salinity - Larvae: Spotted seatrout larvae are consid- 

 ered the most euryhaline of all sciaenid larvae (Killam 

 et al. 1 992). They have been collected in Florida from 

 8.0 to 40.0%o (Rutherford et al. 1989a, Killam et al. 

 1992) and optimal salinity has been reported to range 

 from 20 to 35%o in hatchery conditions (Arnold et al. 

 1976, Killam etal. 1992). 



Salinity - Juveniles: Juveniles seem to prefer mesohaline 

 and polyhaline waters where salinities range from 8 to 

 25%o (Peterson 1986). They have been collected in 

 waters with salinities ranging from to 48%o (Gunter 

 1 945, Wang and Raney 1 971 , Wagner 1 973, Peterson 

 1 986, Rutherford et al. 1 989a, Killam et al. 1 992). 



Salinity - Adults: Adults are considered euryhaline and 

 have been collected over a salinity range of 0.2 to 75%o 

 (Simmons 1957, Perret et al. 1971, Mercer 1984, 

 Killam et al. 1992). Juveniles and adults appear to 

 prefer moderate salinities (Wagner 1973). Optimum 

 salinities, as judged by swimming performance, oc- 

 curred at salinities of 20 to 25%° (for fish with a total 

 length (TL) of 174-438 mm), but were reduced above 

 and below these salinities (Wakeman and Wohlschlag 

 1 977). They are rarely collected below 1 0%o or above 

 45%o in south Texas waters. 



Dissolved Oxygen: Fish kills of spotted seatrout that 

 were due to low dissolved oxygen (DO) concentrations 

 have been reported in Mississippi (Etzold and Christ- 



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