Life History of Cobia 
7 
RESULTS 
Size and Age Composition 
Four hundred sixteen cobia were collected. Most ( n = 366) were 
acquired from recreational hook-and-line fishermen, while others came 
from trawls ( n = 34), gill nets ( n = 7), pound nets (n = 4), stop 
nets ( n - 2), long hauls ( n = 2), and purse seine ( n = 1). A majority 
(n = 356) of the specimens came from North Carolina waters, mostly 
from inlet areas. A few specimens were from the Virginia portion 
of Chesapeake Bay (n = 17), and others were collected by port agents 
in South Carolina ( n = 11), and northeast Florida ( n = 15). Research 
trawls (75-ft high-rise mongoose net) from Daytona Beach, Florida, 
to Cape Fookout, North Carolina captured 17 specimens at ocean stations 
in depths 7-17 m. 
Using pooled data from all gear types, 174 male cobia ranged 
from 39 to 136 cm and 0.47 to 32.0 kg, and 182 females ranged 
from 44 to 142 cm and 0.66 to 32.2 kg (Fig. 3). Only 27 of 152 
(17.8%) males, taken by hook-and-line, measured greater than 100 
cm; conversely 91 of 174 (52.3%) of the females caught by the same 
gear were greater than 100 cm (Fig. 3). 
North Carolina enacted bag (2 fish/angler/day) and minimum size 
limits (33 inches [84 cm] FL) for cobia in 1991, thus bringing the 
state in line with corresponding cobia regulations in other south Atlantic 
states and the Federal Fisheries Conservation Zone (3-200 miles from 
shore). Between 1983 and 1990, 261 cobia caught by hook-and-line 
were examined, and 65 (24.9%) were less than 84 cm. Between 1991 
and 1994, only five (5.3%) of 93 fish caught by hook-and-line were 
less than 84 cm, and four of these were 82-83 cm. 
Sectioned sagittae from 326 specimens were examined for opaque 
zone counts (Fig. 2). Mean observed fork length of cobia increased 
with opaque zone count (Table 2). Otoliths with no opaque zones 
distal to the sagittal core presumably came from young-of-the-year 
cobia that averaged 31-cm ( n = 17, range = 21-46-cm). Age 1 cobia, 
or those with one opaque zone distal to the core, averaged 51 cm 
( n = 9, range = 39-64-cm). Mean length of females was larger than 
mean length for males at a given estimated age (Table 2). Maximum 
estimated age was 14 for males, and 13 for females. The von Bertalanffy 
growth coefficient, k, was greater for males than females, although 
mean asymptotic size was larger for females (Table 3). 
Seasonality and Distribution 
Initial catches of cobia by North Carolina anglers usually occurred 
in March or April 50-65 km offshore over rocky outcroppings and 
