FLORIDA KEYS—Fishing captain and adventure guide Nate Weinbaum was in the final hour of a full-day charter in Florida Bay when his clients landed their first and only fish of the day.

The couple was visiting the Florida Keys for the first time, and the wife delivered what was supposed to be the highlight of their saltwater fly-fishing adventure: a redfish nearly three feet long.

It was too big to keep, according to Florida regulations. So they carefully released the fish back into the bay.

Moments later, the water churned. Then it turned red.

“A shark was trailing us along the edge of the channel,” Weinbaum said. “[It] just devoured the redfish.”

His clients’ joy turned to guilt.

“She’s like: ‘I killed that fish,‘“ Weinbaum said. ”’That fish was going on about its way, and I did that. I caught the fish, and I’m responsible for it being devoured 15 feet from the boat.’

“And she’s absolutely right.”

The experience illustrates a problem that, according to local fishermen, has plagued the bay and other U.S. waters with increasing severity over the past 10 years.

Scientists call the problem “depredation.”

That term describes when sharks take advantage of fishermen for an easy meal, taking some or all of a hooked fish when it is being reeled in.

The “tax man,” they said, is normally found in fishing spots that require hours of attention, such as reefs or bridges, where a resident shark might take a small percentage of the fish caught that day.

However, the in-shore fishing in Florida Bay’s vast network of mangroves and grass flats typically involves constant movement from one spot to another. This suggests that the lemon sharks are actively pursuing the fishing boats rather than waiting in a particular spot such as a reef.

“Maybe it’s [an] homage to my guiding ability that they know that I can catch a fish,” Weinbaum said. “I don’t know, but I’m not a fan of it.”

José Trujillo, biologist at the Florida-based Bonefish & Tarpon Trust, has his own word for the shark’s behavior: “kleptoparasitism.” It refers to a predator’s stealing food from another predator.

In this case, the thieving predators are lemon sharks—a protected species that thrives in the Florida Keys. And they are stealing from humans.

Work began in 2024, gathering preliminary data from the charter captains acting as experts on the local ecology. Specifically, the biologists learned which species were stealing which fish most frequently, and from which “hot spots” in the Florida Bay.

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Trujillo told The Epoch Times that the data showed that the primary perpetrators were lemon sharks about five feet to seven feet long, at a point in their development roughly equivalent to the “teenage years.”

Some of those hot spots were found to be in the northwest corner of the bay, deep within Everglades National Park near a town called Flamingo.

These findings made sense to Trujillo, who has an extensive background in studying shark behavior.

Lemon sharks give birth to multiple live pups in shallow water, such as those near Flamingo. The pups find shelter and hunt for food in the grasses and mangroves. There, they socialize and even learn from each other.

In a lemon shark’s “teen years,” its hunting range will still be relatively small, Trujillo said. Once it is longer than seven feet, it typically will move to waters farther away from the group.

These lemon sharks are at a stage in life when they start to pursue bigger fish for meals. Normally, that means expending energy to develop the skills they need to capture prey.

But now, it seems that the young lemon sharks in Florida Bay have learned—and possibly taught each other—that following boats can lead to easy meals. And key to understanding the depredation problem is determining whether they are becoming “specialized” or are just opportunistic.

“[It is the] optimal diet theory, which basically predicts that an animal will try to feed in the most optimal way, where the trade-off between energy expenditure and energy gain is balanced,” Trujillo said.

Normally, sharks use energy to find food, use more energy to pursue that food, and use even more energy to attack and take down that food. The energy gained from the food must justify the energy spent to obtain it.

“This behavior can be opportunistic, or it can be specialized,” Trujillo said. “There are two big differences between these.”

Predators may just happen upon these kleptoparasitic opportunities, he said. That is understandable.

But if a shark recognizes that its boat-focused feeding strategy offers a far greater payoff than self-foraging, it could start to rely on it. That, Trujillo said, would not be good.

“So if you think about fishing, fishing has solved all of those steps for predators,” Trujillo said. “[Humans] have done the search, they have detected the fish, they have done the attack and capture already, and you are at the final stage. So there’s very little energy that [the shark will] need to spend to use that resource.”

The biologists are concerned that this act of plundering has become the young sharks’ primary means of hunting.

“They are smarter than we are in that they let us do the work,” Weinbaum said.

That work involves coaxing the bigger fish out of their hiding spots, unnecessarily exposing them to sharks.

“Fish are not just out roaming the flats,” he said.

“They’re hunkered down, hiding against seaweed and trying their very best to not be detected.

“[That is why] you have a guilt level of harassing these fish, even though you want to catch and release them.”

By making fish easy prey for sharks, fishermen are contributing to the problem, he said. It is a hard truth.

But that exposure is not limited to the time spent reeling the fish into the boat. Once the hook is removed and the pictures are taken, a proper release of the fish can take time.

Often, a fisherman will hold the catch off the side of the boat, helping push water through its gills as it recovers. Once that fish does regain enough strength to push away, it will still swim at a slower speed.

Meanwhile, a nearby shark could be positioning itself in the murky water for a post-catch ambush, regardless of how carefully the release is carried out.

Weinbaum said his client’s anguish three years earlier over witnessing a shark gobbling up her just-released fish has stuck with him the most, despite the increase in incidents over that same time span.

“It ruined her idea of what I do for a living, what my passion is,” Weinbaum said. “And to a greater degree, I think to myself, ‘Maybe she’s not that wrong.’

“But there is no way to fish in most parts of Florida Bay without the risk of anything that you release being eaten by sharks.”

A lot of the fishing done in Florida Bay is catch-and-release, whether because of regulations or the angler’s preferences.

Regardless of reason, the fishermen hope that each release means that the fish—be it a redfish, trout, snook, snapper, bonefish, or tarpon—will get even bigger and live to reproduce, ensuring even better, more plentiful angling experiences in the future.

Teaming up with concerned fishing captains, they kicked off the next phase of their project in late February: Venturing into those Florida Bay hot spots to begin tagging and collecting data from 50 of the local lemon sharks by the end of the year.

On the data side, they will measure the sharks’ length and width, take stool and blood samples, and install acoustic locators in their abdomens to see where they hang out and what they are eating.

“It’s really important that we come out here and get the data to see if the data actually supports what the fishermen are telling us,” Hamlyn told The Epoch Times.

“And then we can go from there to start looking at those data and start analyzing what these sharks are actually doing, and move into creating management practices.”

With Ed Freeling of Florida Keys Fun Fishing at the helm of their boat, the team rumbled out of Islamorada on Feb. 23 about an hour after sunrise in the direction of Everglades National Park.

There, fresh water is supposed to spill out of Lake Okeechobee to disappear into the Caribbean and Gulf of America. And the state’s peninsula dissolves into mangrove islands, sand bars, and shallow seagrass beds.

It is a fisherman’s paradise, home to game species such as redfish, snook, bonefish, tarpon, and more. Pelicans, spoonbills, and ospreys populate the vegetation on protrusions of land. Dolphins and manatees break the surface to catch a breath, then disappear again under the water’s surface.

And troublesome sharks lurk below, unseen.

The team sought the sharks through conventional fishing. Two rods baited with large chunks of game fish were cast off the back of the boat using other bits of fish as chum to lure the sharks in close.

Their prize took the bait at about 2 p.m. The line screeched out of the reel and the shark tried to make a run for it.

Trujillo stood on the bow of the boat, keeping the fishing line on his rod and reel tight.

The captain piloted the boat slowly behind the fleeing shark to prevent too much line from being pulled from the hissing reel.

Trujillo and the shark played nautical tug-of-war for nearly 10 minutes. Cheers erupted on the boat as the murky water finally revealed a female lemon shark about 6 1/2 feet long.

All hands descended on the quarry, securing her to the side of the boat, flipping her on her back—which put her into a catatonic state—and pointing her nose into the current so water could flow more easily over her gills, allowing her to breathe.

First came the measurements, then samples, then the locator implant, and finally the three-colored dorsal tags.

Hamlyn helped Trujillo keep the shark still while Fleischer took down the notes and passed necessary equipment back and forth.

About half an hour after being hooked, the shark was released to swim away.

Three bright orange tags were permanently affixed to the shark’s dorsal fin, the triangular fin that iconically pokes above the water’s surface. The tags officially identified her in researchers’ records as ORANGE-ORANGE-ORANGE.

As of April 7, Trujillo’s team has recorded 17 lemon sharks, tagging 12 of them with a three-color code.

Researchers out of Florida Atlantic University published a study in the Journal of Marine Science that said 43 percent of captains surveyed between October 2021 and July 2022 reported experiencing depredation, with sharks making up 86 percent of those reported instances.

But down in the Florida Keys, local scientists and fishermen tend to their local problems. Trujillo, Hamlyn, and Fleischer will now observe how many times tagged sharks including ORANGE-ORANGE-ORANGE are caught depredating.

Once researchers know how many sharks are becoming specialists in snatching food caught by humans, they can better investigate why.

Some speculate that the sharks’ behavior is at least partially to blame for a seagrass die-off that has led to depleted fish populations. Having more anglers in the area also may be partially to blame, experts theorize.

There is hope that the research and the management options it informs could help bring balance back to the ecosystem. That might mean lifting some of the lemon shark’s protections, allowing repeat offenders to be killed.

Bull sharks can already be “harvested” in limited amounts, and regulations are in place to combat shark finning.

Weinbaum and other fishing captains, who still hold fast to their love for what they do, enthusiastically describe the excitement they and their clients experience when wrestling with a big shark on a fishing line.

Trujillo opposes allowing sharks to be caught and killed, at least for now, voicing concern that harvesting depredating sharks might only eliminate competition and allow more young sharks to pick up the behavior.

Whatever the solutions may be, the team of researchers holds fast to the hope that balance can be restored to the ecosystem.

According to Hamlyn, that would allow fishermen “to maintain their livelihood because it’s so important to the Florida economy, having people coming down and fishing places like this.”

“You’ve always got to hope,” she said.