Gl. Siegwarth, IDENTIFICATION OF HATCHERY-REARED CHANNEL CATFISH BY MEANS OF PECTORAL SPINE CROSS-SECTIONS, Transactions of the American Fisheries Society, 123(5), 1994, pp. 830-834
Cross sections of pectoral spines were used to identify hatchery-reare
d and wild channel catfish Ictalurus punctatus in the Buffalo River, A
rkansas. Stocked, catchable-size catfish could be identified by wide g
rowth increments between the first and second annuli (corresponding to
rapid hatchery growth) followed by narrow annual increments beyond ag
e 2 (corresponding to slower posthatchery growth). For stocked fish, t
he mean width between the first and second annulus of the spine sectio
n was 3.4 times wider than the mean width between the second and third
annulus. In wild fish these widths were not significantly different.
This growth pattern for stocked fish was verified by using pectoral sp
ines obtained from marked hatchery fish stocked in 1990 and 1991, and
by comparing back-calculated lengths of suspected hatchery fish at age
2 with the length at stocking. By the use of this method, it was dete
rmined that previously stocked catfish accounted for more than 92% of
the catfish sampled in the Buffalo River. This technique should be app
licable in other regions if catchable-size channel catfish are being u
sed in stocking programs and if the growth rate for hatchery fish exce
eds that of wild fish.