WyanskI et al.; Growth, population age structure, and aspects of the reproductive biology of Epinephelus niveatus 



209 



Figure 7 



Histological section of gonad tissue from a 787-mm-TL snowy grouper captured in July 

 in which transition to male is nearly completed. Chromatin nucleolar (arrows) and 

 perinucleolar oocytes are still present. Bar = lOOp. 



mature female was 483 mm, and the largest imma- 

 ture female was 634 mm. The estimate of Lj^ was 

 486 mm (logit model; 95Vf CI=449-509 mm) and A-^ 

 was not estimated owing to the absence of specimens 

 younger than age 3. A third data set, specimens col- 

 lected by NMFS during 1973-81 primarily from head- 

 boats, exhibited a pattern of size at maturity similar 

 to that found for the 1980-85 samples, though sample 

 sizes were <10 in every length intei'val and only three 

 specimens were <55 1-575 mm (Table 8). 



Snowy grouper were in spawning condition from 

 April through September based on the presence of 



hydra ted oocytes (Fig. 9A) and postovulatory follicles 

 ( Fig. 9B ), with no obvious peak period ( Fig. 10 ). Given 

 the small sample sizes for October through March, 

 the spawning season could be longer. Ninety-nine 

 female specimens were captured in spawning condi- 

 tion. Seventy-two percent of the specimens were col- 

 lected on research vessels off South Carolina (32°28' 

 to 32"50'N ) at depths of 176-232 m, primarily during 

 May and July through September. The remaining 

 27 fish in spawning condition were collected during 

 April through August on headboats off South Caro- 

 lina, on research vessels off North Carolina between 

 Cape Fear and Cape Lookout, and by commercial 

 fishermen on the upper continental slope off North 

 and South Carolina; exact location data were not 

 recorded. Commercial fishermen reported approxi- 

 mate locations of 32°36' to 33°51'N and depths of 

 189-302 m for spawning fish. 



Trawl collections during exploratory squid cruises 

 in June 1978 also provided evidence that snowy grou- 

 per spawn on the upper continental slope (Fig. 1). 

 Four large catches ( 1160 fish/8776 kg), which were 

 made at depths of 180-316 ni off North Carolina, 

 South Carolina, and Georgia (not shown), ranged 

 from 90 to 520 snowy grouper per tow. Tow distance 

 ranged from 7.4 to 18.5 km and estimates of snowy 

 grouper density ranged from 2.2 fish/ha to 10.9 fish/ha 

 (13.5 kg/ha to 79.5 kg/ha). Although the reproduc- 



