312 
Fishery Bulletin 117(4) 
0.003 - 
0.002 - 
>, 
Th 
c 
<D 
Q 
0.001 - 
0.000 - 
300 600 900 
Total length (mm) 
Figure 1 
Density plots of total length for all snowy grouper (Hyporthodus 
niveatus ) captured during 1979-2012, off North and South Carolina, 
with 4 gear types: Kali pole, long bottom longline (LBLL), short bot¬ 
tom longline (SBLL), and snapper reel. The unit for density is the 
relative proportion of fish that were caught with a particular gear 
type. /i=number of fish sampled. 
The results of analyses of size and age distributions, 
mean length, mean age, and size at age all indicate signif¬ 
icant differences among periods. Density plots comparing 
TL by period show similarities in overall size range; 
however, a Kolmogorov-Smirnov test revealed 
that the size, as well as age, distributions were 
significantly different among periods (P<0.001; 
Fig. 2, A and B). In addition, both mean TL and 
mean age differed significantly among periods 
(Tukey’s honestly significant difference: adjusted 
P<0.001). The mean size and age offish increased 
from 584 mm TL and 5.5 years in the 1990s to 
632 mm TL and 6.8 years in the 2000s (Table 2); 
however, these values are noticeably less than the 
means of 714 mm TL and 11.8 years for samples 
from the 1980s. Size at age of specimens caught 
only with bottom longline gear (long and short) 
was significantly different between the 2 recent 
periods, the 1990s versus the 2000s, for ages 3-12, 
except it remained the same for age 4 (minimum 
n> 20, P<0.05). A significant decrease in size at age 
was detected for age 3 and ages 6-12, with size at 
age increasing only for age 5 (Table 3). 
The analyses of von Bertalanffy growth param¬ 
eters revealed some differences among periods 
(Fig. 3, Table 4). Growth curves for the 1990s and 
2000s had the same growth coefficient (k-0.12), 
with a slight decrease of the asymptotic length 
(L<J in the 2000s. The 1980s had the lowest k value 
(0.085) and the lowest (1004 mm TL) (Table 4). 
Sexual pattern 
Conclusive evidence for the diagnosis of sexual 
pattern has not been presented previously for 
snowy grouper. We confirmed that this species is 
a protogynous hermaphrodite by the capture of individu¬ 
als having gonads with 1) a-stage atresia in vitellogenic 
oocytes within developing male tissue and 2) sperm 
sinuses in the gonadal wall (Fig. 4). The results of 
Table 1 
Number of snowy grouper (Hyporthodus niveatus ) for which otoliths and gonads were examined per 
period by gear type. Specimens were caught off North and South Carolina as part of fishery-independent 
(FI) and fishery-dependent (FD) surveys during 3 periods: 1982-1985, 1993-1994, and 2008—2012. Val¬ 
ues in the “Other” row represent the total numbers combined for the following gear types: hook and line, 
University of Rhode Island high-rise trawl, blackfish trap, experimental trap, Florida trap, and unknown. 
Number of fish 
Otoliths examined Gonads examined 
Gear type 
Source 
1980s 
1990s 
2000s 
1980s 
1990s 
2000s 
Long bottom longline 
FI 
53 
0 
5 
70 
0 
5 
FD 
22 
1215 
999 
0 
146 
1074 
Short bottom longline 
FI 
0 
0 
379 
0 
0 
389 
Kali pole 
FI 
94 
0 
0 
82 
0 
0 
Snapper reel 
FI 
115 
1 
0 
204 
1 
0 
FD 
57 
308 
10 
1 
22 
0 
Chevron trap 
FI 
0 
78 
83 
0 
77 
82 
Other 
FI 
10 
2 
15 
11 
2 
16 
Total 
351 
1604 
1491 
368 
248 
1566 
