On Tuesday, Nov. 29, Mote Marine Laboratory scientists released 320 hatchery-reared juvenile snook into Phillippi Creek 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 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 winter freezes — in 2010 a winter cold spell resulted in the deaths of millions of snook and the closure of the fishery — continue to reduce snook stocks periodically. Thus, for more than 25 years, Mote and Florida’s Fish and Wildlife Conservation Commission (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.
This most recent snook release study, as part of Mote’s fisheries enhancement partnership with FWC and a new privately funded Fisheries Conservation and Enhancement Initiative at Mote, scientists will tag and release 10,000–15,000 hatchery-reared snook in several locations in Sarasota and Manatee counties, including Bowlees Creek, Whitaker Bayou, Hudson Bayou, Phillippi Creek, North Creek and South Creek.
By dividing fish among different pilot release experiments, Mote scientists can learn more about the local snook population.
For example, on Nov. 29 Mote released about 40 fish at eight different release sites to document, which shoreline habitat types juvenile snook prefer along Phillippi Creek, a 7-mile, estuarine tidal creek system that offers diverse habitats for young snook.
“These eight different sights are among shorelines that vary in complexity,” said Dr. Ryan Schloesser, postdoctoral scientist at Mote. “We are releasing the fish at seawalls that are clear of vegetation, seawalls that have vegetation and completely natural sites. The goal is to determine how snook utilize these different shoreline types. We’d like to find out whether or not snook reside in natural habitats longer or do disperse more quickly from seawalls with no vegetation than those seawalls with vegetation. The ultimate goal is to provide this information to homeowners so that they can make fish-friendly decisions with their shorelines.”
Results of this study will help reveal how well the creek shorelines supports native fishes and how resource managers might enhance creek benefits.
“One of the major goals of the Fisheries Ecology & Enhancement Program is to develop responsible guidelines to release hatchery-reared snook into the wild to help keep the population sustainable,” Schloesser said. “What this project is doing is learning a little bit more about what snook need to be happy and healthy out in the environment.”
Mote will monitor the released snook in Phillippi Creek using passive integrated transponders (PIT tags) similar to the microchips for cats and dogs.
“These tags communicate with our PIT tag antennae rays, which are placed at all eight release sites,” Schloesser said. “Any time a snook with a PIT tag swims over a wire loop that we have under the water, an electromagnetic field charges this tag, which then gives out a little pulse that has the information regarding which individual fish was at that spot at that time.”
With participation from area residents, Mote researchers and volunteers installed eight special antenna arrays along Phillippi Creek to detect tagged snook within range.
A sister project that scientists are also working with these 10.000 – 15,000 snook into Phillippi Creek is to document how snook releases may impact the fishery, now that Mote scientists have identified optimal release strategies based on many years of research. By tagging most of the fish with coded-wired tags (CWTs), Mote scientists can identify Mote-raised fish recaptured later, and know where and when they were released.
Scientists are then able to identify how hatchery-reared fish impact the local fishery and if they are caught by fishers. Mote’s William R. Mote Memorial Snook Shindig, a catch-and-release research tournament involving the community, is one method Mote uses to recapture snook and evaluate the success of releases.
Earlier this year, 2,175 released snook were coded-wire tagged and released into Hudson and Whitaker Bayous at the same time so scientists can compare their survival rates. If snook fare better at one site, the researchers can investigate why.
This research is funded in part through Mote’s Fisheries Conservation and Enhancement Initiative, which received tremendous support from philanthropists Carol and Barney Barnett, leadership donors to Mote’s Oceans of Opportunity campaign. That project is coupled with Mote’s partnership with FWC’s Fish and Wildlife Research Institute, which also funds this research.