Young-of-the-year spot and Atlantic croaker are 

 found in nursery areas from late winter to early sum- 

 mer. Postlarval and early juvenile croakers usually con- 

 centrate near sources of fresh or brackish waters that 

 flow through marshes and deltas or over tidal flats be- 

 fore entering bays. Studies within marshes (Herke 

 1971, Conner and Truesdale 1972, Arnoldi et al. 1973) 

 indicate that the deeper low-salinity areas are the pri- 

 mary nursery habitat for postlarval and early juvenile 

 croakers. In contrast, postlarval and juvenile spot are 

 usually found in brackish to saline marsh areas (Parker 

 1971, Sabins 1973). Adults of both species tend to 

 concentrate in deeper, firm-bottomed inland open 

 water areas (especially over and near reefs), while 

 young fishes tend to occupy shallow, soft-bottomed 

 areas (Reid 1955, White and Chittenden 1976). 



Greatest concentrations of Atlantic croaker in in- 

 land open water areas along the Louisiana coast are in 

 the Chenier Plain (Perret et al. 1971). In the nearshore 

 Gulf, croakers contribute more than half of the average 

 catch per effort (by weight) in the industrial bottom- 

 fish trawl fishery (Moore et al. 1970). Spot, on the ave- 

 rage, account for only 1 1% of the demersal catch in the 

 North Central Gulf of Mexico (Roithmayer 1965). 



Although no analyses of croaker or spot food 

 habits have been conducted in the Louisiana Chenier 

 Plain, investigations in northern Gulf estuaries indicate 

 that they are roughly similar throughout the area 

 (Pearson 1929, Gunter 1945, Reid 1955, Reid et al. 

 1956, Darnell 1958, Parker 1971, Day et al. 1973). In 

 Barataria Bay, croakers are more onmivorous, feeding 

 on micro- and macrobenthic animals, small fishes, and 

 organic detritus (Day et al. 1973). Darnell (1958) re- 

 ported on the feeding habits of Atlantic croaker in 

 Lake Pontchartrain. Very young fish (less than 25 mm 

 or 1 in) subsist largely on zooplankton (epecially the 

 copepod Acartia tonsa). Croakers (35 to 50 mm or 1 to 

 2 in) fed primarily on small benthic organisms. Larger 

 juveniles and young adults (50 to 200 mm or 2 to 8 in) 

 fed primarily on organic detritus. Adult croakers fed 

 mainly on small fishes, shrimp, crabs, and mollusks. 



Darnell (1958) reported that spot undergo two 

 feeding stages in the course of individual development. 

 Very young spot graze mainly on plankton, but they 

 also eat microcrustaceans. Adults are chiefly bottom 

 feeders. Major crustaceans consumed by spot include 

 harpacticoid copepods, ostracods, isopods, and arnphi- 

 pods. As growth continues, bottom-burrowing organ- 

 isms such as the brackish-water clam, Rangia cuneata, 

 and organic detritus constitute a large portion of the 

 diet. 



Feeding activity patterns of croaker and spot dif- 

 fer (Darnell 1958). Young croakers (less than 75 mm 

 or 3 in) feed at low intensity in the early morning, 

 gradually increase to a peak in eariy afternoon, and 

 taper off toward evening. Intermediate-sized fish (75 to 

 150 mm or 3 to 6 in) feed moderately throughout the 

 day with a slight increase in feeding intensity toward 

 evening. Adult croakers feed moderately throughout 

 the day, but show a greater feeding intensity during the 

 mid-morning and early evening hours. Spot feed mostly 

 at twilight and during the hours of darkness. 



Various sizes of Atlantic croaker prefer different 

 temperatures and salinities. Parker (1971) collected 

 croakers ' in abundance ' at salinities from 0.2%o to 

 35.1%o and concluded that salinity per se had little 

 effect on their distribution. His data, however, as well 

 as those reviewed by Copeland and Bechtel (1971) and 

 Conner and Truesdale (1972), indicate that young At- 

 lantic croaker prefer slightly or mo.'erately brackish 

 waters. Croakers have been encountered at tempera- 

 tures of 0.4° to 38° C (32° to 100° F). The young ap- 

 pear to be well adapted to 6° to 20° C (45° to 68° F), 

 but older fish are noticeably absent at temperatures 

 below 10° C or 50° F (Parker 1971, Gallaway and 

 Strawn 1974). 



Spot also exhibit a wide salinity and temperature 

 tolerance. Adults appear to avoid temperatures below 

 10° C (Parker 1971, Perret et al. 1971). In contrast to 

 Atlantic croakers, very young spot appear to prefer 

 brackish to high-salinity areas as nurseries. 



5.5.6 SPOTTED SEATROUT (Cynoscion nebulo- 

 sus) and RED DRUM (Sciaenous ocellata) 



Spotted seatrout and red drum are highly valued 

 estuarine-dependent sport and food fishes that inhabit 

 coastal waters of the Gulf, estuaries and marshes. Both 

 have a strong tendency to school. 



Spotted seatrout do not have strong migratory 

 habitats. Since they tend to be resident in a given 

 coastal area, catastrophic depletion of a local popula- 

 tion could have serious long-term effects (Tabb 1966). 

 Despite their non-migratory tendencies, spotted sea- 

 trout are frequently stimulated to move from one area 

 to another because of particular ecological conditions. 

 For example, this species tends to congregate along 

 beaches for short periods when prolonged southeastern 

 winds result in lower turbidities. 



Most young red drum migrate seasonally from 

 their spawning grounds near tidal passes to nearby in- 

 shore nursery grounds. Adults and older juveniles, 

 called ' rat reds ' by fishermen, migrate to low-salinity 

 marsh lakes, bayous and canals during cold months. 

 They move into inundated grassy areas with high tides, 

 and retreat from them with outgoing tides. Large adults 

 ('bull reds ') migrate to the outer reaches of estuaries 

 and shallow waters of the Gulf to spawn (Pearson 1929, 

 Simmons and Breuer 1962). 



Although spotted seatrout spend most of their life 

 in estuaries (Tabb 1966), adults and larger juveniles 

 commonly inhabit nearshore Gulf waters. Red drum 

 are also sometimes widespread in the nearshore Gulf 

 and adjacent estuaries. 



The ecology of spotted seatrout is based largely on 

 the studies of Tabb (1966) in the more saline and less 

 turbid estuaries of western Florida and southern Texas. 

 He noted that one of the principal deficiencies in 

 knowledge about the species is the lack of data on 

 regional differences in habitats. For example, most of 

 the classical studies indicate a strong dependence upon 

 shallow ' grass flats ' as nursery habitat for postlarval 



257 



