Life History of Cobia 
15 
All Areas (N = 94 stomachs) 
% iri 
70 
60 
50 
40 
30 
20 
10 
0 
< 4.5 4.5 - 9.0 > 9.0 
Cobia Size Class (kg) 
Eiasmobranchs 
LjTeleosts 
Crabs 
Shrimps 
Fig. 4. Percent iri’s for various prey groups by cobia mass interval (intervals 
arbitrarily chosen). 
in importance (Fig. 4). Eiasmobranchs, that is, the smooth dogfish 
and dasyatid sting rays, were consumed almost exclusively by cobia 
greater than 9 kg. Seventy-five percent (50 of 67) of female cobia 
from North Carolina sounds and inlet areas had food in their stomach 
at capture, suggesting that these areas may be foraging grounds before 
and after spawning. 
Reproduction 
One hundred and twenty-seven male and 113 female cobia were 
sexed and staged for maturity in the field. Most male cobia were 
developing or ripe (Table 7). The latter state was characterized by 
active spermatogenesis and copious amounts of sperm within testicular 
ducts (Fig. 5a). Mean gsi’s for males increased from 3.0 (SD = 1.2, 
n = 14) in May, to 4.7 (SD = 1.5, n = 44) in June, then declined 
slightly to 4.4 (SD = 1.6, n = 7) in July. Most male cobia were 
sexually mature by 60-65 cm FL (Table 7), or age 2. 
Most female cobia examined were staged as developing (Table 
7), and most were sexually mature by 80 cm FL, or age 2. Histological 
sections revealed that the ovaries of early developing females had 
