Habitat-related predation on
juvenile wild-caught and hatchery-reared red drum Sciaenops ocellatus
(Linnaeus)
G.W. Stunz, T.J. Minello-2001-06-15 Journal of
Experimental Marine Biology and Ecology, 260(1): 13-25
Abstract:
We examined the patterns of habitat-specific
mortality for newly settled red drum (Sciaenops ocellatus) using an
experimental mesocosm approach. Experiments were designed to analyze prey
vulnerability and fish rearing-type (wild-caught or hatchery-reared) in
estuarine habitats of varying structural complexity including marsh (Spartina
alterniflora Loisel), oyster reef (Crassostrea virginica Gmelin),
seagrass (Halodule wrightii Aschers), and nonvegetated sand bottom.
We used two different predators, pinfish (Lagodon rhomboides Linnaeus)
and spotted seatrout (Cynoscion nebulosus Cuvier). For both
predators, vulnerability of wild-caught red drum was significantly lower in
structurally complex habitats such as seagrass and oyster reef; the highest
vulnerability was associated with the nonvegetated bottom. This habitat
effect was not apparent for hatchery-reared prey. In trials using a
combination of both rearing-types, there was no significant habitat effect
on prey selection, but hatchery-reared red drum suffered higher overall
mortality than wild-caught fish from pinfish predators. In these trials,
spotted seatrout did not select for either prey type. Differences we
observed in prey vulnerability were likely caused by behavioral differences
between wild-caught and hatchery-reared red drum. Our results reinforce the
conclusion that structural complexity in estuarine habitats increases
survival of newly settled fishes. Our data also suggest that hatchery-reared
red drum may be more vulnerable to predation than natural fishes, and that
survival of stocked fish may be enhanced through habitat-related behavior
modification.
(Fishery Ecology Branch, National Marine Fisheries
Service, Southeast Fisheries Science, Center, Galveston Laboratory, 4700
Ave. U, Galveston, TX 77551, USA, Tel.: +1-409-766-3706; fax:
+1-409-766-3520, e-mail: greg.stunz@noaa.gov)