FISHERY BULLETIN: VOL. 86, NO. 2 



a low of 8% in May to a high of 45% in September 

 (Table 5). An average of 27.5% of the females 

 captured during the spawning season were run- 

 ning ripe, corresponding to an average spawning 

 frequency of once every 3.6 days or 50 times dur- 

 ing the 6-mo spawning period. 



The spawning frequency was also estimated 

 from females that were undergoing final oocyte 

 maturation (FOM) between the hours of 0600 and 

 1400 in April, May, July, and August 1984 and 

 1985 (Table 5). For comparison, the actual per- 

 centage of running ripe females captured during 

 the same months is also presented. An average of 

 42.8% of the females examined for final oocyte 

 maturation from April through August were 

 undergoing FOM. Therefore, average spawning 

 frequency was once every 2.3 days, or 80 times 

 during the 6-mo spawning season. 



Spawning frequency was also estimated from 

 the percentage of females captured with ovaries 

 containing postovulatory follicles (POF). An av- 

 erage of 13.1% of the females captured had 

 ovaries which contained POF ranging from 12 

 hours to 2 days old. This would correspond to a 

 spawning frequency of once every 7.6 days or 24 

 times during the spawning season. 



Finally, the spawning frequency of four female 

 C. nebulosus in the laboratory under conditions of 

 controlled temperature and photoperiod were ex- 

 amined (Table 6). The fish spawned from 1 to 10 

 times each month for 17 months, an average of 17 

 spawns per individual over a 12-mo period (Table 

 6). This would correspond to a spawning fre- 

 quency of once every 21 days. 



DISCUSSION 

 Sexual Maturity and Spawning Season 



Male spotted seatrout reached sexual maturity 

 at a smaller size than females which appears to be 

 a fairly common phenomenon in spotted seatrout 

 throughout its range (see Mercer 1984 for a re- 

 view). Both male and female spotted seatrout in 

 South Texas reached sexual maturity at a size 

 similar to that reported for other groups of C. 

 nebulosus along the Gulf Coast (Moody 1950; 

 Klima and Tabb 1959; Overstreet 1983) and at a 

 smaller size than along the East Coast (Tabb 

 1961; Brown 1981). 



Running ripe females were captured only be- 

 tween one hour before and two hours after sunset 

 in South Texas, suggesting a high degree of syn- 

 chrony in spawning fish. Collections of newly fer- 



Table 5. — Percentage of spotted seatrout spawning (RR) or under- 

 going final oocyte maturation (FOf^) in South Texas. Data on 

 spawning fish collected April 1982-f^ay 1985. Data on fish under- 

 going FOM collected April 1984-IVIay 1985. 



Table 6. — Number of spawns and average 

 water temperature by month for four female 

 spotted seatrout contained in a 30,000 L tank in 

 Porl Aransas, TX, under conditions of con- 

 trolled temperature and photoperiod, July 

 1974-November 1975. Expenmental proce- 

 dures descnbed in Arnold et al. (1976). 



tilized eggs during a 25-h period after sunset (Holt 

 et al. 1985) provides supporting evidence for this 

 spawning synchrony. 



Both histological data and GSI values showed 

 spotted seatrout have an extended spawning sea- 

 son in South Texas. Gronadal recrudescence began 

 in January in male and in February in female 

 spotted seatrout. Spawning commenced in April 

 and continued until the end of September. Other 

 studies of C. nebulosus along the Gulf and East 

 coasts of the United States have also reported 

 long spawning seasons (Mercer 1984). Addition- 

 ally, other sciaenids have extended spawning sea- 

 sons (Merriner 1976; White and Chittenden 1977; 

 DeVries and Chittenden 1982; Love et al. 1984), 



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