Red drum, continued 



ends in early January with peaks occurring in mid- 

 Septemberthrough October, and then declining (Welsh 

 and Breder 1924, Gunter 1945, Yokel 1966, Boothby 

 and Avault 1 971 , Christmas and Waller 1 973, Heffernan 

 1973, Sabins and Truesdale 1974, Perret et al. 1980, 

 Holt et al. 1 981 a, Benson 1 982, Overstreet 1 983, Lee 

 et al. 1 984, Hein and Shepard 1 986a, Peterson 1 986, 

 Matlock 1987, Van Hoose 1987, Murphy and Taylor 

 1990). Gonadosomatic index (GSI) studies in the 

 northern Gulf of Mexico suggest an 8 to 9 week 

 spawning season, mid-August to early October (Wil- 

 son and Nieland 1994). Based on the presence of 

 larval red drum in the northern Gulf of Mexico, it can be 

 inferred that spawning occurs August through Novem- 

 ber, with a peak from September through October 

 (Ditty 1986, Ditty et al. 1988). Spawning principally 

 occurs in nearshore coastal waters on the Gulf side of 

 barrier islands, usually in or near the passes and 

 channels between islands where currents can carry 

 the eggs to shallow inside waters (Higgins and Lord 

 1 926, Pearson 1 928, Gunter 1 945, Breuer 1 957, Yokel 

 1 966, Sabins and Truesdale 1 974, Perret et al. 1 980, 

 Holtetal. 1981a, Benson 1982, Lee et al. 1984, Hein 

 and Shepard 1986a, Matlock 1987, Peters and 

 McMichael 1987, Murphy and Taylor 1990). Freshly 

 spawned eggs were recovered during one investiga- 

 tion in water depths ranging from 1 .5 to 2.1 m (Johnson 

 and Funicelli 1991). One study estimated spawning 

 occurring 7.3 to 21.9 m offshore of a natural pass in 

 Texas (Heffernan 1973). In Florida, ripe adults have 

 been collected 4.8 km offshore in the Gulf of Mexico 

 suggesting that some offshore spawning may also 

 occur (Murphy and Taylor 1 990). Some spawning can 

 also occur inside large estuaries. Spawning activities 

 are initiated in early evening or night (Guest 1 978, Holt 

 et al. 1981b, Overstreet 1983, Johnson and Funicelli 

 1991), in an average salinity of 28%o and in tempera- 

 tures of 21 ° to 24°C (Hopkins et al. 1 986, Johnson and 

 Funicelli 1991). 



Fecundity : Captive fish spawn repeatedly and produce 

 large numbers (about 1 million per spawn) of small 

 buoyant eggs (Vetter et al. 1983). The estimated 

 number of oocytes from a female with a standard 

 length (SL) of 758 mm was 61,998,776 when calcu- 

 lated by volumetric means or 94,513,172 using the 

 gravimetric method (Overstreet 1983). In one experi- 

 ment, 10 to 12 spawns per fish over 90 to 100 days 

 were typical with one captive fish spawning 31 times 

 over 90 days, while another reported 3 females spawn- 

 ing 52 times in 76 days producing an estimated total of 

 60 million eggs. Captive fish spawned about 1 million 

 eggs per spawn during the first 45 days, dropping to 1 

 to 100 thousand thereafter. The maximum recorded 

 spawn was 2,058,000 perfish during one night (Arnold 

 et al. 1979, Overstreet 1983), and a maximum indi- 

 vidual annual fecundity is estimated as 30,000,000 for 



9 to 14 kg fish (Overstreet 1983). In the northern Gulf 

 of Mexico, Wilson and Nieland (1994) reported a 

 typical batch spawning frequency of 3 days, and a 

 batch fecundity range of 160,000 to 3.27 million eggs 

 for females 3 to 33 years old. 



Growth and Development 



Egg Size and Embryonic Development : Eggs develop 

 oviparously. They are buoyant, and their shape is 

 spherical with a mean diameter of 0.95 mm and a range 

 of 0.86 to 0.98 mm diameter (Ditty and Shaw 1994). 

 Usually one and up to six clear oil globules averaging 

 0.27 mm (0.24-0.31 mm) are present. Theperivitelline 

 space varies in size, but is generally less than 2% of the 

 egg diameter (Holt et al. 1981b, Vetter et al. 1983). 

 Eggs spawned at 24°C and 28%> hatch in 19 to 20 

 hours (Arnold et al. 1979), 22 hours when spawned at 

 23°C and 36%o (Vetter et al. 1 983), and 28 to 29 hours 

 at 22 to 23°C (Holt et al. 1981b). Live eggs float with 

 the oil globule on top, and animal pole downward. Holt 

 et al. (1 981 b) has thoroughly described the embryonic 

 development of this species. Hatching usually occurs 

 in late summer to early winter, peaking in September 

 and October (Matlock 1987). 



Age and Size of Larvae : Larvae are less than 8.0 mm 

 SL, and those 8 to 15 mm SL are considered transi- 

 tional juveniles (Peters and McMichael 1 987). Larvae 

 are either transparent with no pigment patterns at 

 hatching, or have a compressed band of dendritic 

 melanophores on the ventral surface of the body in the 

 yolk sac region (Holt et al. 1981b). Newly hatched 

 larvae are negatively buoyant with a SL range of 1.71 

 to 1 .79 mm (mean 1 .74). Three days after hatching, at 

 25°C, the mouth forms, eyes are pigmented, and more 

 time is spent swimming to stay near the surface. The 

 swim bladder is well developed by day 4 and larvae 

 remain in a horizontal position in the water column with 

 little effort (Holt et al. 1 981 b). The yolk sac is present 

 in larvae 3 to 5 mm TL, but has disappeared at 7 mm 

 TL. Temperature has a pronounced effect on larval 

 growth (Holt et al. 1 981 b, Lee et al 1 984, Comyns et al. 

 1 984). In laboratory raised fish, the yolk sac stage can 

 range from 40 hours at 30°C to 85 hours at 20°C (Holt 

 et al. 1981a, Holt et al. 1981b), and larval weight 

 increase can average 17.74 |ig/day at 24° and 30.25 

 (ig/day at 28°C. Larvae in the field grow at faster rates 

 than similar aged laboratory spawned larvae (Comyns 

 et al. 1989). Wild larvae have an average weight gain 

 of 141 |ig/day at 27.8° to 29.0°C. The growth rate for 

 wild larvae smaller than 4 mm is about 0.3 mm/day, but 

 growth increases rapidly in sizes greater than 4 mm 

 (0.42 mm/day for 4 to 6 mm larvae). Two distinct 

 growth periods are evident in early larval development. 

 One extends from hatching through depletion of the 

 yolk sac, while the other begins with the onset of active 

 feeding. Growth rate in terms of SL was low in the first 



296 



