NOTE Murphy et al.: Direct validation of ages determined for Pogonias cromis 
383 
Total length (mm) 
Figure 2 
Total length-frequency distribution (mm) for black drum that were 
tagged and released (line, n=707) and for those that were recap- 
tured (bars, n=26). 
of the sulcus acousticus with the aid of an Optimus 
digital-image processing system. 
Figure 1 
Sampling area for black drum along the 
Atlantic coast of Florida. Most sam- 
pling was done in the area shown by 
diagonal lines just west of Cape Can- 
averal. Some sampling was also done 
in the southern portion of Mosquito 
Lagoon. 
structing anglers to contact us. The OTC provided a 
reference mark defining the otolith margin at the 
time of initial capture; all recaptures of fish whose 
otoliths were recovered were made by biologists dur- 
ing sampling trips conducted in August 1993 and 
January, October, and December 1995. 
Recaptured fish were sacrificed and returned to 
the laboratory, where they were measured for total, 
fork, and standard lengths; weighed to the nearest 
tenth of a kilogram; and sexed macroscopically. Sag- 
ittal otoliths were excised and stored dry. An Isomet 
low-speed saw was used to make transverse cuts near 
the core of the whole otolith. Otolith sections were 
about 0.5-mm thick and were mounted on glass slides 
with coverbond mounting media. Opaque bands and 
OTC marks were examined with a compound dissect- 
ing microscope (4x magnification) equipped with an 
ultraviolet light source. Distances from the otolith 
core to the proximal edge of the OTC mark and to 
each opaque band distal to the OTC mark were mea- 
sured along the axis from the core to the ventral edge 
Results and discussion 
A total of 707 adult black drum, from 515 to 1,237 
mm TL, were captured, injected, and tagged during 
this study. Twenty-six of these fish were recaptured, 
and their otoliths were excised. Lengths of recaptured 
black drum ranged from 656 to 1,011 mm TL (Fig. 2). 
Most of the large (>1,050 mm TL) adult black drum 
found in our sample came from a school of very large 
fish caught in southern Mosquito Lagoon; according to 
two tag returns (see below), this school had apparently 
left the area shortly after tagging and release. 
Ages of recaptured black drum ranged from 3 to 
13 years (Table 1); 16 were age 8 and older and were 
likely to have been mature adults at time of recap- 
ture (Murphy and Taylor, 1989). Time-at-large for 
recaptured fish was from just over a month to just 
less than three years, i.e. 42-1,031 days. 
Observations of the number of opaque bands de- 
posited since the fish had been marked supported 
our hypothesis that one band formed each year from 
the late winter to early spring. We observed that five 
fish tagged during February or June 1993 and recap- 
tured 42-176 days later in August 1993 had not depos- 
ited an opaque band since being marked (Table 1 ). One 
fish at large for 555 days between June 1993 and 
January 1995 had deposited one band since release. 
All other fish recaptured had been at large for 805 to 
1,031 days, during which two late-winter to early- 
