Hams and McGovern: Changes in the life history of Pagrus pagrus 
737 
Table 2 
Sampling data for the four study periods 1972-74, 1979-81, 1988-90, and 1991-94. 
Year 
Fish sampled 
No. aged 
Mean fork length (mm) 
Mean age (years) 
No. sexed 
1972-74 
13,120 
222 



1979-81 
1,933 
1,177 
293 
3.07 
1,397 
1988-90 
1,853 
1,261 
254 
2.44 
727 
1991-94 
3,850 
1,843 
257 
3.062 
2,169 
Total 
20,756 
4,503 
268 
2.86 
4,293 
ing 1991-94, in contrast with 7% at the same size 
interval during 1979-81 (PcO.OOl; Table 4). In 1979- 
81, male red porgy constituted 12% of the fish exam- 
ined at 351^00 mm TL compared with 32% in 1988- 
90 (PcO.Ol) and 49% in 1991-94 (PcO.OOl; Table 4). 
Size-at-maturity of female red porgy has also 
changed. Female red porgy became sexually mature 
at smaller sizes in 1991-94 than in 1979-81. During 
1991-94, female red porgy first became sexually 
mature at 176-200 mm TL (mean age=0.9). 
In 1979-81, the first mature female was at 
201-225 mm TL (mean age=0.9) (Table 5). 
There were significantly more mature fe- 
males (54%; PcO.OOl) at 251-275 mm TL 
(mean age=1.9) in 1991-94 than during 1979- 
81 (27%; mean age=1.7). 
1988=1994 
A total of 2,629 live bottom stations and 5,265 
red porgy were sampled May through August 
1988-94, of which 4,349 specimens were kept 
for life history studies (Table 6). The major- 
ity of the samples were collected with chev- 
ron traps. During 1988 and 1989, there was 
no difference between the size range of red 
porgy collected in chevron traps and the size 
range of red porgy collected in blackfish 
traps, Florida traps, hook-and-line gear, or 
all three of these gear types combined (Fig. 
5). Similarly, there was no difference in the 
size range of red porgy sampled by hook-and- 
line gear and chevron traps between 1990 
and 1994 (Fig. 5). Between 1988 and 1991, 
however, the mean size of red porgy captured 
with hook and line was significantly larger 
each year than the mean size of porgy taken 
with the remaining gear types (Pc0.05), al- 
though there was no significant difference be- 
tween mean size of fish captured with the gear types 
used in 1993 and mean size of fish captured with the 
gear types used in 1994. The size of red porgy 
sampled during 1988-94 ranged from 90 to 501 mm 
Table 3 
Von Bertalanffy growth equation parameters derived from 
the mean back-calculated fork length for each time period. 
Parameter 
1972-74 1979-81 1988-90 1991-94 
k 
0.226 0.343 0.273 0.281 
459.3 391.4 382.7 356.4 
FL. The mean size was 256 mm FL, with the highest 
frequency occurring at 240 mm FL. The length fre- 
quency of aged red porgy was very similar to the 
length frequency of all red porgy sampled. 
Age (years) 
Figure 2 
The mean size at capture for red porgy collected in 1972-74, 1979- 
81, 1988-90, and 1991-94. Ages for red porgy collected between 1972 
and 1974 were taken from Manooch and Huntsman (1977). 
