SARASOTA -- Scientists of Mote Marine Laboratory and Florida’s Fish and Wildlife Conservation Commission placed hatchery-reared juvenile snook into acclimation enclosures in Sarasota Bay – and will release the fish into the wild from the enclosures Friday, Aug. 14 – as part of an ongoing research project focused on finding the most effective methods to replenish and enhance wild snook populations.
Snook are one of the most sought after catches in Florida’s saltwater recreational fishing industry. According to the American Sportfishing Association, Florida is the top-ranked state in economic output from recreational fishing, which draws more than $8 billion to the economy annually. Saltwater fishing alone generates about 80 percent — more than $6 billion — of that income.
Increased fishing pressure and environmental concerns such as weather patterns and red tide have contributed to a serious decline in snook population, which placed them on the state's list of "species of special concern" in the 1980s. As a result, fishing restrictions and careful monitoring led to a rebound in snook abundances in the 1990s.
However, occasional environmental pressures such as red ride and cold winter freezes - in 2010 a winter cold spell resulted in the deaths of millions of snook and the closure of the fishery - still continue to reduce snook stocks periodically. Thus, for more than 25 years, Mote and FWC scientists have partnered on research studies designed to evaluate whether stocking hatchery-reared snook can be an effective fishery management tool for rapidly replenishing snook stocks following the periodic mortality that red tides and cold weather can cause.
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“FWC and Mote Marine Laboratory have worked closely together to determine the most effective way to enhance marine fish populations in Florida since 1985,” said Chris Young, director of FWC’s stock enhancement program. “At FWC, we always strive to further Mote’s research and offer our support in these snook releases.”
This most recent snook release study – made possible thanks to a private donation to Mote and from funding provided by FWC – involves tagging about 400 juvenile common snook born and raised at Mote Aquaculture Park with passive integrated transponders, transporting the fish to acclimation enclosures located in a creek in Sarasota Bay and then releasing the fish into the wild.
The PIT tags provide a reliable “barcode” for each individual fish to help scientists accurately track and recover data from the fish, and the acclimation enclosures allow for the fish to adjust to their new environment following transportation to the release site.
One key part of this project is the conditioning some of the snook have undergone prior to release and the introduction of acclimation enclosures. “About half of the snook, our control group, has been raised in a traditional aquaculture manner – in a big, round open tank and using artificial feed. The other half has received conditioning, or live prey as food and shelter to mimic the outside environment, which will help the fish prepare for life in the wild,” said Kenneth Leber, associate vice president for Mote’s Directorate for Fisheries and Aquaculture.
This project is designed not only to determine whether snook that have been conditioned for release at Mote have better growth and survival rates in the wild, but to also assess the impact that acclimation enclosures may have on survival of conditioned fish.
“For this project, we are asking a fundamentally new question, which is if we condition the fish, feed them live prey and give them shelter much like they would find in the wild, and then transport them to these acclimation enclosures, will they survive longer and do even better than the control group that is placed in the acclimation enclosures without conditioning,” Leber said.
Past Mote and FWC research conducted through pilot snook releases has shown hatchery-reared fish released into the wild can make an impact in the replenishment of these populations, but the specific release site where these fish are released can make a huge difference in their growth and survival.
“One of the things we learned from four past pilot-release studies with this fish is that not all habitats lend the same survival rates for snook,” Leber said. “We’ve released snook in various creeks and mangrove sites and we have determined that we can improve the survival of hatchery-reared snook by about 10 times just by choosing the right habitat. We have also determined that if the fish are acclimated in enclosures for three days prior to releasing them, then that doubles their survival.”
These results are key to developing large-scale stocking techniques that can help rapidly increase populations of species like snook, which are affected by environmental impacts such as red tides, unusually cold winter temperatures and hurricanes.
“It is not so important that we do this in Sarasota Bay as it is that we’re evaluating a technique that can be used all over South Florida for a fish that is so valuable to the sport fishing industry,” Leber added. “Taking the fishing pressure off these fish and waiting for several years for a comeback is one way, but here is another new tool that can be used to help rapidly recover these fish populations.”