Elucidating Impacts of Pre-Release Physical Stressors on Post-Release Success of Hatchery-Reared Spotted Seatrout

Alteration of habitat associated with coastal development and increased demand for food and recreation can result in the depletion of fisheries resources such as the spotted seatrout (Cynoscion nebulosus), the Gulf of Mexico’s most popular recreational fish.  Stock enhancement, or the release of cultured fish to supplement wild populations, is one potential tool for managing important fisheries resources. Although large economic and human efforts have been allocated to enhancement of some marine species, the effectiveness of stocking is not well established and techniques for ensuring success have not been well developed. The ecology and life history of the spotted seatrout have been studied extensively, but comparatively little is known about its physiology, including how it responds to physical stressors in aquaculture settings. Hatchery environments can affect many learned behaviors; however, the role of stress associated with handling, transport, and release processes in the success or failure of spotted seatrout stock enhancement is unknown. My research is focused on the impacts of physical stressors and the subsequent stress response on growth and survival of fish upon release. I have assessed cortisol production during real time hatchery-release processes followed by a 30-day field experiment in which I have examined the effect of a high magnitude stressor (i.e., release procedures) and subsequent increase in cortisol to post-release survival and growth in both 50- and 100-mm fish. No difference was seen in survival between 50-mm control and experimental treatments, both exhibiting 93% survival. 100-mm fish; however, exhibited substantial differences in survival. 100-mm control fish exhibited 87% survival while experimental fish exhibited 26% survival.