738 
Fishery Bulletin 95(4), 1 997 
Figure 3 
The mean back-calculated size at age for red porgy collected in 1972- 
74, 1979-81, 1988-90, and 1991-94. Back-calculated lengths for red 
porgy collected between 1972 and 1974 were derived from scale ages. 
Age and growth 
Ages were obtained for 2,935 (67%) of the red 
porgy otoliths collected (Table 6). Agreement 
between the first and second reader averaged 
93%, and was never less than 90% for any 
year. The mean observed size-at-age declined 
for most ages between 1988 and 1994 (Table 
7), although there was a significant increase 
in the mean age of red porgy over the study 
period (Fig. 6; PcO.Ol; r 2 =0.94). The mean 
observed size-at-age for red porgy 2 years and 
older sampled during 1988 and 1989 was sig- 
nificantly larger than all other years, with 
the mean observed size-at-age in 1992 and 
1993 consistently the smallest (Table 7; Fig. 
7). Above age 6, growth rates appeared to 
taper off sharply for all years (Fig. 7). Age-6 
red porgy collected during 1988 had the third 
highest mean length recorded for all age 
classes in any year. Similar to the mean ob- 
served size at age, mean back-calculated size 
at the most recent annulus was significantly 
larger for 1988 and 1989 compared with other 
years for ages 2 and greater and also ap- 
peared to reach asymptotic size at age 6 for 
each year (Table 8; Fig. 8). 
The von Bertalanffy growth curves fitted 
to the mean back-calculated size at most re- 
cent age (ages 1-10) for each year demonstrated some 
differences between years (Fig. 9), with growth curves 
from 1988 and 1989 showing larger fish at age, and 
higher L m and k. Both k and tended to decrease dur- 
ing the study period, although neither of these trends 
were significant (linear regression; P>0.05; Fig. 10). 
No significant differences were apparent in size 
distribution, age distribution, or size-at-age between 
Table 4 
Percentage of male red porgy relative to the total number of individuals sexed during 1979-81, 1988-90, and 1991-94. A signifi- 
cant difference (% 2 ; PcO.Ol) in the proportion of males for a particular size class collected during 1979-81 is denoted by “A”. A 
significant difference (% 2 ; PcO.Ol) in the proportion of males that were collected during 1988-90 is denoted by “B”. 
Size (mm TL) 
1979-81 
1988-90 
1991-94 
Total 
Males 
%Males 
Total 
Males 
%Males 
Total 
Males 
%Males 
<200 
19 
— 
— 
16 
— 
— 
57 
— 
— 
200-250 
216 
— 
— 
140 
2 
1.43 
372 
4 
1.08 
251-300 
271 
10 
3.69 
163 
5 
3.07 
491 
33 
6.72 s 
301-350 
313 
21 
6.71 
226 
25 
11.06 
814 
194 
23.83^ 
351-400 
239 
29 
12.13 
136 
44 
32.35 A 
371 
183 
49. 33^ 
401-450 
160 
38 
23.75 
38 
17 
44.74 A 
57 
25 
43. 86^ 
451-500 
158 
108 
68.35 
8 
4 
50.00 
6 
4 
66.67 
501-550 
18 
12 
66.67 
— 
— 
— 
1 
— 
— 
551-600 
2 
1 
50.00 
— 
— 
— 
— 
— 
— 
Total 
1,397 
220 
727 
97 
2,169 
443 
