Aquaculture America 2020

February 9 - 12, 2020

Honolulu, Hawaii

KEY FACTORS INFLUENCING POST-RELEASE SURVIVAL OF HATCHERY-REARED JUVENILE SNOOK Centropomus undecimalis

Ryan  W. Schloesser* ,  Paula Caldentey , Nathan P. Brennan , and  Kenneth M. Leber,
Fisheries Ecology and Enhancement Program 
Mote Marine Laboratory
Sarasota, Florida 34236, USA
rschloesser@mote.org 

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.