This past June, for the second year in a row, Mote Marine Laboratory scientists released more than 20,000 hatchery-raised juvenile snook into waterways along Southwest Florida. These large-scale releases represent the latest progress in a 30-year, science-based stock enhancement program aimed at maintaining ecological balance and supporting the state’s $14 billion recreational fishing industry.

“One of the reasons that we’re focused on snook is it’s an important game fish in the region,” said Dr. Ryan Schloesser, manager of Mote’s Fisheries Ecology & Enhancement Program. “If you want snook, you’re coming to Florida. If snook are doing really well, the economy is doing well.”

But in addition to their popularity with recreational anglers — snook cannot be harvested commercially — the fish are sensitive to environmental factors. Cold snaps and red tide can cause large-scale fish kills. In 2018, for instance, a particularly severe red tide outbreak put a strain on the local population.

Still, replenishing the species is not as simple as dumping a bunch of fish into the wild.

“We dump a bunch of fish with best practices,” Schloesser clarified.

The releases of nearly 60,000 fish over the past two years have utilized decades of coordinated research and development by Mote scientists, often in concert with efforts and information from the Florida Fish and Wildlife Conservation Commission, or FWC.

The research revealed, among other things, that snook are homebodies. They don’t stray far, and they tend to return to their place of origin. Even if they were raised in a hatchery and released at 6 months old, they’ll keep returning to that release site.

“If we put snook in your backyard, that’s its new home,” Schloesser said. “We had one fish that was released prior to my coming to Mote. Six years later that fish was caught about 100 feet from where it was put in the water.”

Armed with that information, scientists can pinpoint the most favorable release sites based on places where fish kills have been reported, optimizing population replenishment without creating overcrowding and competition for resources.

The juvenile snook are raised at Mote Aquaculture Research Park in east Sarasota, but their parents are all wild fish harvested from local waters to serve as broodstock for the program. Genetically, they’re Southwest Florida snook.

“They’re essentially the fish that belong here,” Schloesser said. “There’s no way externally that you’d be able to distinguish our fish from wild fish. The only thing that differs is we have temperature control [in the hatchery], so they actually grow a little faster than they would in the wild.”

The temperature control also allows for a more effective breeding program. Rather than waiting for summer, when snook spawn naturally, scientists at the research park can change conditions in their tanks and encourage the broodstock to reproduce sooner. This allows the enhancement program to respond more quickly to fish kills rather than waiting more than a full year.

The fish are raised for up to eight months and reach between 3 and 6 inches long.

“That’s about the size of a fish that we would expect in the spring from a wild spawn the previous year,” Schloesser explained.

After their cozy early months, young hatchery-raised snook, which Schloesser calls “naive juveniles,” face an uphill battle surviving in the wild. The post-release learning curve takes five or six weeks, and their chances are best when they don’t have to compete with too many wild fish for food and places to hide from predators.

“They’ve never seen a heron or an osprey, let alone a jack crevalle,” he added.

According to earlier studies, the typical survival rate is 20% to 30%.

Prior to the 2025 large-scale release, Mote typically released only about 5,000 snook at a time. Scientists studied the effectiveness of those efforts using electronic monitoring stations to track movement and survival rates. But those stations were prohibitively expensive for use in a large-scale operation.

Now, scientists have recorded the genetic information of the broodstock so they can use “genetic tracking” to determine how well hatchery-raised fish are integrating into the wild population.

“We can use that like the different genetic websites look at your heritage,” Schloesser said.

When that time comes, anglers will play a valuable role in the research. People who catch snook will have the opportunity to take a simple fin clip and give it to Mote for study.

In the meantime, people out on the water can act as much-needed scouts for the Mote team, either through periodic surveys or by reporting fish kills to the FWC Fish Kill Hotline.

“What they see is not something I see every day,” Schloesser said. “Luckily, we have great fishing collaborators. Please report if you see fish kills. If you’re asked to complete a survey on the satisfaction of the waterway, do it. If we don’t know because nobody tells us, then we can’t respond and help them.”