Rotunno and Cowen: Temporal and spatial spawning patterns of Peprilus triacanthus 
789 
1000 - 
1000 - 
Tucker 1988 (summer only) 
Tucker 1989 
800 - 
1 1 Summer 
800 - 
Spring 
n = 2,984 
1 1 Summer 
600 - 
600 - 
n = 881 
400 - 
400 - 
200 - 
200 - 
1 C 
D 
0 - 
J 
1 1 PPpPrrr-j-r i I , p i rrp 
0 - 
J 
llWrrrrrr-rirrMMMMMMiMMiM.MM -rrrrrrr i rr t 
0 5 10 15 20 25 30 35 40 45 50 55 0 5 10 15 20 25 30 35 40 45 50 55 
Standard length (mm) 
Figure 2 
Length-frequency histograms for Peprilus triacanthus collected by net during the spring and summer of 
1988 and 1989. 
Morphometries 
A wide range of sizes of Peprilus were collected dur- 
ing both seasons of 1988 and 1989. Because size-fre- 
quency distributions had the same mode on all cruises 
within a season, length frequencies were combined for 
all fish sampled with a particular gear during each sea- 
son each year. Spring-collected 1988 fish ranged in size 
from 6 to 43 mm SL (Frame; Fig. 2A). Similar size dis- 
tributions of fish were found for the 1989 spring cruises: 
4.7 to 37.5 mm SL (Frame; Fig. 2B) and 2 to 6 mm SL 
(Tucker; Fig. 2D). The 1988 summer trawls collected 
fish between 5 and 29 mm SL (Frame; Fig. 2A) and 1.3 
to 36.0 mm SL (Tucker; Fig. 2C). Summer 1989 fish 
ranged in size from 6.0 to 50.0 mm SL (Frame; Fig. 2B) 
and 1.7 to 49.0 mm SL (Tucker; Fig. 2D). 
Deep- and shallow-bodied fish were identified from 
both the spring and summer samples in both years. 
Fish had BD-SL ratios ranging from 0.119 to 0.750 
(Fig. 3, A and B). There was an indication of two 
modes during both spring and summer of 1989. These 
BD:SL ranges overlap with ranges reported by Horn 
(1970) and Ditty (1981) for all species (Table 2). Fur- 
ther analysis of body depth: standard length demon- 
strated that body depth increases allometrically with 
respect to standard length up to a size of 10 to 15 
mm SL (Fig. 4). Body depth subsequently remained 
about 50% of length for each year. 
Meristics 
Ninety-nine percent of the fish collected with the 
Frame net in 1988 and 1989 had either 18 or 19 cau- 
dal vertebrae (of those, approximately 90% had 19 
caudal vertebrae; Table 3). Counts of either 18 or 19 
caudal vertebrae are consistent with those reported 
for P. triacanthus (Table 3). The number of caudal 
vertebrae was not related to body depth. According 
to Ditty and Truesdale ( 1983), juvenile P. burti and 
P alepidotus have mean body depth-standard length 
ratios of greater than 0.557 and caudal vertebrae 
counts of 17-18. However, our findings indicate that 
fish with high body depth-standard length ratios also 
had 19 caudal vertebrae. 
The fish we sampled had between 8 and 16 ventral 
midline melanophores. Ditty ( 1981) reported ranges of 
4 to 8 ventral midline melanophores for B burti and 11 
to 17 for P triacanthus. Seventy-six percent of our speci- 
