12 
Joseph W. Smith 
Table 5. Percent frequency of occurrence (/), percent number ( n ), percent mass (w), 
and index of relative importance (iri) of food items in cobia stomachs from North Carolina 
and adjacent waters, 1987-90. 
Prey Taxa / n w iri 
Mollusca 
Cephalopoda 
Loligo plei 
0.9 
0.2 
<0.1 
<1 
Arthropoda 
Crustacea 
Stomatopoda 
Squilla sp. 
2.7 
0.7 
0.4 
3 
S. empusa 
3.6 
1.3 
2.5 
14 
S. neglecta 
1.8 
4.2 
2.5 
12 
Decapoda 
Penaeidae 
Penaeus sp. 
3.6 
0.9 
0.2 
4 
P. aztecus 
6.4 
2.9 
3.7 
42 
P. setiferus 
0.9 
0.2 
0.2 
<1 
Trachypenaeus constrictus 
0.9 
1.5 
<0.1 
<1 
Sicyoniidae 
Sicyonia sp. 
3.6 
7.9 
2.7 
38 
Palaemonidae 
Palaemonetes vulgaris 
0.9 
0.4 
<0.1 
<1 
Crangonidae 
Crangon septemspinosa 
4.5 
2.6 
0.2 
13 
Upogebiidae 
Upogebia sp. 
0.9 
0.2 
<0.1 
<1 
Albuneidae 
Albunea gibbesii 
0.9 
0.2 
0.1 
<1 
Portunidae 
Ovalipes sp. 
6.4 
3.7 
2.0 
36 
O. ocellatus 
2.7 
0.9 
1.1 
5 
0. stephensoni 
6.4 
4.6 
4.0 
55 
Callinectes sp. 
7.3 
3.3 
1.8 
37 
C. sapidus 
30.0 
15.4 
19.2 
1,038 
C. similis 
3.6 
0.9 
0.8 
6 
Portunus sp. 
3.6 
1.1 
0.5 
6 
P. gibbesii 
5.5 
2.2 
1.8 
22 
P. spinimanus 
2.7 
0.7 
1.4 
6 
Unidentified portunid remains 
4.5 
2.2 
0.3 
11 
Xanthidae 
Menippe mercenaria 
0.9 
0.4 
0.1 
<1 
Unidentified decapod remains 
0.9 
0.2 
<0.1 
<1 
Chondrichthyes 
Carcharhinidae 
Mustelus canis 
6.4 
6.1 
21.2 
175 
