The common snook (Centropomus undecimalis ) supports a valuable recreational fishery in southwest Florida, but mass mortality events due to cold stuns and red tide suggest stock enhancement is needed to aid population recovery and adaptive management of the fishery . To guide effective marine fisheries enhancement with common snook, timely estimation of post-release survival is required, but this has been particularly challenging to measure for estuarine and marine finfishes . W e apply novel principles for release activities of hatchery-reared juvenile c ommon snook in southwest Florida to guide timely estimation of post-release survival, focusing on the influence of season, in-hatchery conditioning, and release site acclimation and habitat.
Over the last 4 years, Mote Marine Laboratory has employed replicate release designs to stock >15,00 0 juvenile s tagged with passive integrated transponder (PIT) tags during experimental release efforts. These h ypothesis-driven release experiments were conducted in four tidal-creek systems monitored with marine-adap ted PIT tag antenna arrays that provided recapture histories capable of being analyzed with Cormack-Jolly-Seber mark-recapture models.
Models suggest that the success of snook stocking efforts are primarily dependent on the specific location and time at which individuals are released. In particular, the availability of n ursery habitat at release sites may be a critical factor influencing post-release survival in southwest Florida because important habitat has been lost to coastal development and shoreline hardening. Yet, t he use of variable tag sizes, pre-release acclimation to habitat, and predator-exclusion cages during release also influenced rates of survival and detectability of hatchery-release fish. The highest survival rates were observed for individuals released in the lower reaches of the tidal creek systems in the spring, indicating these areas may provide ideal release sites for juvenile fishes at that time. S hort-term differences in survival among the first four weeks after release primarily influenced the overall impact of the stocking activity, and these survival rates were consistently identified after one year of monitoring. The application of these novel release activities to aid adaptive-management can identify optimal release sites, times, and protocols that will promote adaptive management of stock enhancement programs and maximize the impact on receiving populations.