252 
Fishery Bulletin 96(2), 1998 
Table 2 
Diet of pelagic preflexion (PF ) summer flounder, P. dentatus, 
larvae collected from the NW Atlantic, in terms of numeri- 
cal percentage composition (%N), volumetric percentage 
composition (%Vol), percentage frequency of occurrence 
(%FO), and percentage index of relative importance (IRI = 
(%N + %Vol ) x %FO). All values are based on a sample 
size, with prey, of 250 larvae. 
Prey 
%N 
%Vol 
%FO 
%IRI 
Tintinnids 
28.7 
3.3 
37.6 
19.3 
Copepod nauplii 
20.0 
10.2 
41.2 
20.0 
Copepodites 
16.0 
61.4 
30.0 
37.3 
Calanoids 
0.6 
4.9 
2.0 
0.2 
Cyclopoids 
0.6 
2.0 
2.4 
0.1 
Copepod eggs 
16.0 
1.2 
34.8 
9.6 
Bivalve larvae 
12.1 
14.8 
28.0 
12.1 
Invertebrate eggs 
3.7 
0.9 
11.6 
0.9 
Other 
2.3 
1.3 
9.2 
0.5 
Table 3 
Diet of pelagic flexion (FLX) summer flounder, P. dentatus , 
larvae collected from the NW Atlantic, in terms of numeri- 
cal percentage composition (%N), volumetric percentage 
composition (%Vol), percentage frequency of occurrence 
(%FO), and percentage index of relative importance (IRI = 
( %N + %Vol) x %FO). All values 
size, with prey, of 22 larvae. 
are based on a 
sample 
Prey 
%N 
%Vol 
%FO 
%IRI 
Polychaete larvae 
1.2 
0.5 
4.5 
0.1 
Copepod nauplii 
2.3 
0.2 
9.1 
0.2 
Copepodites 
68.6 
66.7 
86.4 
92.8 
Calanoids 
13.9 
27.5 
18.2 
6.0 
Cyclopoids 
3.5 
1.9 
9.1 
0.4 
Copepod eggs 
3.5 
<0.1 
9.1 
0.3 
Bivalve larvae 
5.8 
2.8 
4.5 
0.3 
Invertebrate eggs 
1.2 
0.4 
4.5 
0.1 
The well-digested condition of copepodites precluded 
specific identifications, but most appeared to be 
calanoids. The only other prey category to represent 
more than 10% of the diet by any analysis was adult 
calanoid copepods, which despite accounting for 
27.5% of dietary volume, composed only 6.0% IRI. 
Tintinnids were not observed in the FLX larval 
diet, and other small prey items (copepod nauplii, 
copepod eggs, bivalve larvae, and invertebrate eggs) 
contributed little to the diet. The mean number of 
prey ingested by FLX larvae was 3.9 (SB=2.33, 
range=l-9). 
Diet of oceanic premetamorphic and 
rrsetamorphic fPIWI+IWSJ larvae 
A total of 9 PM and 8 M specimens were represented 
in this study: 44.4% of PM larvae and 37.5% of M 
larvae contained recognizable prey, and 55.6% of PM 
larvae and 62.5% of M larvae had empty guts. 
Lengths at the time of examination ranged from 4.8 to 
7.6 mm SL for PM larvae and 5.8 to 9.0 mm SL for M 
larvae (Table 1). Combining the two stages (PM+M): 
41.2% contained prey, and 58.8% had empty guts. 
As with earlier morphological stages, immature 
copepodites were the primary prey for PM and M 
larvae, accounting for 50.1% of the diet (IRI). How- 
ever, adult calanoid copepods and appendicularians, 
the secondary and tertiary prey (in terms of IRI), 
together contributed more than twice as much as 
copepodites to dietary volume (Table 4). Although it 
was not always possible to identify copepods to spe- 
cies, the most frequently ingested calanoid copepod 
Table 4 
Diet of pelagic postflexion, premetamorphic (PM), and 
metamorphic (M) summer flounder, P. dentatus , larvae col- 
lected from the NW Atlantic, in terms of numerical per- 
centage composition (%N), volumetric percentage compo- 
sition (%Vol), percentage frequency of occurrence (%FO), 
and percentage index of relative importance (IRI = ( %N + 
%Vol) x %FO). All values are based on a sample size, with 
prey, of 7 larvae. Data exclude copepod eggs that appeared 
to have been ingested incidentally. 
Prey 
%N 
%Vol 
%FO 
%IRI 
Copepod nauplii 
8.7 
0.5 
28.6 
1.7 
Copepodites 
60.9 
27.1 
42.9 
50.1 
Calanoids 
13.0 
34.6 
42.9 
27.2 
Appendicularians 
17.4 
37.8 
28.6 
21.0 
appeared to be Centropages typicus. Tetnora longi- 
cornis and Pseudocalanus spp. also contributed to 
the diet. Appendicularians were only observed in the 
diet of PM and M larvae. 
The mean number of prey ingested by PM and M 
larvae was 3.3 (SD=2.14, range=l-6). Copepod eggs 
that were abundant in the gut of a single M-stage 
larva were excluded because they were probably in- 
gested incidentally. 
Incidence of feeding 
An examination of incidence of feeding (defined as 
the percentage frequency of larvae with prey in their 
guts) in relation to 2-h time blocks over the course of 
