Red drum, continued 



stage, averaging less than 0.06 mm/day or more (Lee 

 etal. 1984). 



Juvenile Size Range : Transformation to the juvenile 

 stage occurs at a total length (TL) of approximately 12 

 mm (Ditty and Shaw 1994). The size range for the 

 juvenile stage is from 8.0 mm SL until about 40 mm TL 

 (Gunter 1 945, Peters and McMichael 1 987). Above 10 

 mm TL, pigment rapidly appears with distinctive color 

 patterns at about 25 mm TL. Twenty to 50 dark distinct 

 blotches are present at this point from the lateral line to 

 the dorsal fin on each side of the trunk. At 36 mm TL, 

 a pronounced chromatophore enlargement at the base 

 of the upper part of the caudal fin appears that results 

 in the characteristic black ocelli. Juveniles are morpho- 

 logically identical to adults by 42 mm TL except for a 

 slightly more pointed caudal fin and lack of distinct 

 ocelli. Ocelli are faintly visible at 50 mm TL and are very 

 apparent at 75 mm TL. Brown lateral blotches enlarge 

 with the fish until it reaches 1 50 mm TL, and then tend 

 to fade and finally disappear (Pearson 1 928, Simmons 

 and Breuer 1962). Growth tends to be sporadic in 

 juveniles, averaging 18.8 mm TL/month or 20.4 mm 

 SL/month for the first 7.5 months of life (Bass and 

 Avault 1975). Other estimates based on Texas red 

 drum report sizes of 320 to 360 mm SL for the first year, 

 500 mm SL for the second year, 550 to 600 for the third 

 year, 875 mm SL for the sixth year, 925 mm SL for the 

 seventh year, and 975 to 1000 mm SL for the eighth 

 (Miles 1950). Growth has been expressed modally in 

 year class lengths of: 340 mm SL first year, 540 mm SL 

 second year, 640 mm third year, 750 mm SL fourth 

 year, 840 mm SL fifth year; 330 to 356 mm first year, 

 484 to 559 second year, 660 to 762 mm third year, 890 

 to 965 fourth or fifth year (Johnson 1978). Growth is 

 rapid until age 4 or 5 years and then slows markedly 

 (Murphy and Taylor 1990). Sexual maturity occurs at 

 the end of the third, fourth, or fifth year with 5 year old 

 fish constituting the bulk of the spawning population. 

 Males mature at smaller sizes than females with most 

 mature at age 1 or 2, and all mature by age 3 years. 

 Some females are mature by age 3, and all are mature 

 by age 6 years (Pearson 1928, Simmons and Breuer 

 1962, Johnson 1978, Benson 1982, Murphy and Tay- 

 lor 1 990). Red drum generally mature at approximately 

 700 to 800 mm TL (Miles 1950, Simmons and Breuer 

 1962), with 50% of the males maturing when they 

 reach a fork length (FL) of 529 mm and 50% of the 

 females mature by 825 mm FL (Murphy and Taylor 

 1990). Smaller ripe fish are occasionally found. Ma- 

 ture fish have been collected in Texas as small as 425 

 mm TL. Males are presumed to mature at a smaller 

 size than females and have been reported to reach 

 maturity at 320 to 395 mm in Mississippi. Another study 

 reported ripe males 500 mm SL and ripe females 550 

 mm SL from Texas samples (Gunter 1 945, Miles 1 950, 

 Perretetal. 1980). In Florida, some males and females 



are mature by 400 and 600 mm FL, respectively (Yokel 

 1966, Murphy and Taylor 1990). A Louisiana study 

 reported spawnable males ranging 779 to 1 1 30 mm TL 

 and spawnable females ranging 850 to 1 135 mm TL 

 (Hein and Shepard 1 986a). Wilson and Nieland (1 994) 

 reported that both males and females reach maturity in 

 the northern Gulf of Mexico at four years of age, when 

 females are 690-700 mm fork length (FL) and 4.0-4.1 

 kg total weight (TW), and males are 660-670 mm FL 

 and 3.4-3.5 kg TW. 



Age and Size of Adults : Average adult size is 800 to 850 

 mm SL (Pearson 1 928, Miles 1 949). This is a long lived 

 species with fish surviving over 37 years (Johnson 

 1 978, Mercer 1 984, Beckman et al. 1 988, Murphy and 

 Taylor 1 990). A 36 year old female was 995 mm FL and 

 weighed 1 1 .96 kg, and a 37 year old male was 940 mm 

 FL and weighed 10.49 kg (Beckman et al. 1988). 

 Pearson (1928) recorded a 1520 mm TL fish. The 

 largest red drum caught by hook and line was caught 

 in North Carolina waters and weighed 42.69 kg (WRGF 

 1991). The red drum fishery is largely comprised of 

 newly recruited fish. The mean size and age of this 

 population depends heavily on recent recruitment 

 (Tilmant et al. 1989). Beckman et al. (1988) have 

 derived Von Bertalanffy growth equations for both 

 sexes of red drum by length and by weight. 



Food and Feeding 



Trophic Mode : All free swimming life stages are car- 

 nivorous. Juveniles appear to hunt for food using a 

 sweep style method to search for suitable prey (Fuiman 

 and Ottey 1993). 



Food Items : The red drum diet consists of food items 

 from five major groups: copepods, mysid shrimp, am- 

 phipods, decapods, and fish (Bass and Avault 1975, 

 Levine 1 980). Utilization of these groups is determined 

 by prey size and availability (Boothby and Avault 1 971 , 

 Bass and Avault 1975, Overstreet and Heard 1978, 

 Morales and Dardeau 1 987), and so their dominance 

 in the diet of red drum may vary among locations. 



Larvae: The major prey of larval red drum are copep- 

 ods, including cyclopoids, calanoids, and harpacticoids, 

 as well as various other zooplankton (Bass and Avault 

 1975, Benson 1982, Peters and McMichael 1987). 

 Larvae up to 9 mm TL subsist on copepods and their 

 nauplii that range from 0.06 to 1 .5 mm TL (Bass and 

 Avault 1975, Comyns et al. 1989). The calanoid 

 Acartia sp. is eaten most frequently, but species of 

 cyclopoids, harpacticoids, and other calanoids are 

 also consumed. 



Juveniles: Although they appear in the diet of juveniles 

 10 to 39 mm TL, copepods cease to be important in 

 volume by 1 to 1 9 mm TL. Mysid shrimp, particularly 



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