A FLAT-OUT MYSTERY

The Search for Bonefish Pre-Spawning Aggregations in the Keys Intensifies

BY T. EDWARD NICKENS

Captain Rick Ruoff was running late, a not-unusual circumstance when the fish were biting and he was a long way from home. With angler Bill Levy on the bow, he was making the 20-mile trek from Key Largo to Islamorada, deep into an early 1990s November afternoon. It was calm and he was in a hurry, so he ran a bit offshore, in some 15 feet of water. “I took a course straight down the beach,” he recalls, “and I saw these tails zipping out of the water in front of us. I said to Bill, Holy hell, what is that? And it was a ball of bonefish. Thousands of them, tumbling like a bowling ball. The bottom fish would come up, and the top fish would go down.”

Ruoff eased up to the school, and Levy cast and almost instantly had a fish. Then he hooked another. Ruoff backed the boat away to keep from disturbing the school, and said to Levy, “Let’s just sit here and watch.”

He and Levy watched the bonefish boil at the surface for nearly an hour, until the falling sun prompted the men to head for port. Ruoff, who has guided for 52 years, shakes his head at the memory. “It was incredible,” he says. “I had not seen anything like that before, and I haven’t seen it since. But boy did I get a good look then. And I feel pretty honored to have seen it just once.”

At the time, Ruoff wasn’t certain what he’d witnessed. But now he knows what stopped his skiff cold that late November day. It was a pre-spawning aggregation (PSA) of Florida Keys bonefish, a phenomenon that has been shrouded in mystery for decades.

Ruoff’s story—and a double handful of similar recollections told by other long-time Keys fishing guides—has helped refocus a project essential to Florida Keys bonefish conservation: The search for bonefish pre-spawning aggregations in the Florida Keys. The project will expand in the fall of 2021, combining technology with guide observations in an effort to solve one of the most intriguing mysteries on the Florida flats: Where do Florida Keys bonefish spawn?

The answer is a missing link in the scientific understanding of what is known about Florida Keys bonefish reproduction.

A bonefish school in the Florida Keys.

Tyler Bowman

Recent research has provided tantalizing clues, including four probable PSAs reported by fishing guides. Two years ago, BTT scientists outfitted Keys bonefish with acoustic transmitters to track their initial spawning migrations. “On a full moon they swam as many as 30 miles,” says Dr. Ross Boucek, manager of BTT’s Florida Keys Initiative. “One fish tagged at the Content Keys migrated 45 miles through the backcountry out to the reef. The fish was last detected at depths greater than 110 feet, presumably on its way to spawn offshore. Not only are we narrowing down the areas where to look, but from the tracking information, we’re also getting a clearer picture of when to be out in the water at these sites. This is a great foundation for the work that will unfold over the next three years.”

Based on findings in the Bahamas, scientists know these movements are the opening act in the full drama of the spawning season, and that bonefish gather in huge aggregations that could number in the thousands before heading to deep water to spawn. Over a decade of hard work, BTT scientists interviewed guides to identify possible pre-spawning locations, sampled bonefish hormones and eggs to estimate peak spawning times, and tracked fish from their home ranges to spawning areas. The results? At least seven PSAs have been identified and three protected by the Bahamas through national park declarations.

But despite intense scientific scrutiny—and within the context of their impassioned pursuit by anglers—the locations of these spawning areas in the Florida Keys, if they exist at all, have been an elusive target. While a years-long effort in the Bahamas has identified multiple PSAs in that archipelago, finding these critical sites in the Keys has involved decades of dead ends. Now, thanks in large measure to the support of Keys guides, BTT is taking the Bahamian playbook of oral history, acoustic monitoring, spatial analysis, and hard-boiled detective work to a new level on the southern flats of the Sunshine State. And time is of the essence.

“Discovering these spawning sites is the first step to learning what stresses our bonefish may face when they spawn in the Keys,” says Boucek. “Once we find these sites and identify stresses spawning bonefish face, we can work through advocacy and education channels to fix problems and ensure our bonefish can spawn. This will ensure a sustainable population.”

Dr. Ross Boucek (right) implants an acoustic transmitter into a Keys bonefish.

Ian Wilson

Pinpointing these locations will also connect other pieces of the puzzle, beginning with a greater understanding of how much of the Keys bonefish population is a result of local spawning in the Keys versus larvae drifting in from neighboring countries.

“Finding spawning bonefish in the Keys will answer the questions conclusively about where Keys bonefish come from,” says Carl Navarre, chairman of the board of BTT, who believes documenting spawns will fill gaps in our knowledge left by ocean modeling and genetic analysis. “And if we’re able to find spawning bonefish, and track them like we have in the Bahamas, it will give us a tremendous amount of information on how to better protect them and manage the fishery.”

What makes the timing of this project so perfect is a mix of new technology and old-school sleuthing. As Florida Keys bonefish numbers crawled out of the basement over the last few years, acoustic telemetry technology has matured, and the meteoric rise of drone technology and its applications in the science realm have given researchers new ways of looking for fish aggregations. For the cost of a single hour in a helicopter, BTT could purchase a drone and use it whenever needed.

And critically, there’s been a shift in how anglers in general and flats guides in particular view the role of science in informing fisheries management. BTT has worked strategically to deepen relationships with the flats guiding community around the Caribbean. When Navarre was elected a board member in 2017 and then board chair in 2020, he brought to BTT a deep connection to many Florida guides. A former guide and founding director of The Guides Trust Foundation, one of Navarre’s early signature projects began in the fall of 2020 when he reached out to a few dozen Florida Keys guides to engage them in a cellphone app project to report on the population health of bonefish, tarpon, and permit in the Keys. That initiative, Navarre recalls, “gave us plenty of useful information, but it also opened up lines of communication and started building relationships with guides.”

That is fundamental to the search for bonefish PSAs in the Keys. This past spring, Navarre reached out again, and he and Boucek interviewed seven guides with international reputations to kick off the search for the spawning areas. Between them, Timmy Klein, Harry Spear, Mark Krowka, Rob Fordyce, Bob Branham, Eddie Wightman, and Rick Ruoff have some 200 years of experience on the water. Those guides, as well as others in the Lower Keys, listed 19 different areas where they had seen bonefish PSAs, most occurring in the 1980s and 1990s when Keys bonefish populations were particularly healthy.

Hearing the reports, Boucek was stoked. “In some cases, four or five guides had seen fish at the same place,” he says. As word spread, more guides called in. At two different sites, guides reported seeing bonefish aggregations where there had been similar reports decades earlier. “That was very exciting,” says Boucek. “Those were reports from the same place, during the same time of year, and in the same moon phase where groups of fish had been reported 30 years earlier. Those PSAs were there for a time, and then for years there were no reports at all. Now it seems they are showing up again.”

With the Keys experiencing a significant rebound in fish large enough to spawn, the time for a dragnet approach to discovery seems particularly ripe. In the fall of 2019, BTT tagged 30 bonefish between the Marquesas and Biscayne Bay to begin analyzing possible migration routes to suspected PSAs. Boucek honed his drone-flying skills through dozens of test flights over open water. In the next phase, BTT will be testing a new generation of acoustic tags that will reveal the maximum depth attained by tagged fish, which should help pinpoint the dates when bonefish spawn since they only head for deep water to spawn.

With the excitement comes a renewed sense of purpose. No one knows how long the current bonefish revival will last. “We can’t say if this is a sign of good things to come,” says Boucek, “or if this is an anomaly. We don’t know if they’ll be around in five years. With so much uncertainty, there is an urgency to find them now.”

Here’s how it will work: Pulling together all the available data, BTT has assembled a short list of 11 locations for further scrutiny, and now the cat-and-mouse game begins. Starting this fall, Boucek and a small team will run BTT’s 22-foot Pathfinder to a suspected location during the full and new moons, and fly a drone in a grid search pattern from noon to sunset. “The expectation is that the aggregation should get more organized and be more visible at the surface the closer you get to sunset,” says Boucek. The team will search for two days on both the full and new moons, from November to May. Boucek figures there is still plenty of room for trial and error in the process, but with each passing month the target areas should come into greater focus. “It’s like catching lightning in a bottle,” he explains. “We think we have the bottle. We just need the lightning to show up when we have it in our hands.” Bonefish don’t spawn on every new or full moon, and weather conditions have to be right to run the boats at long distances at night.

Navarre doesn’t discount the difficulty of the undertaking. “This is not an easy thing to do,” he cautions. The process in the Bahamas, he notes, unfolded over many years. The Keys search, he figures, could take five years or more. Or the search team could get lucky. “But one thing that will drive success in the Keys is an outreach program for guides,” he continues. “They need to know exactly what we’re looking for and have ways to contact us immediately so that we can have teams ready to go at the drop of a hat.”

And if the PSAs can be found, and the spawning areas identified, opportunities for conservation can become much more focused. At this point, any management prognostications are premature. What’s most important is for the science to close the circle on the long search for Florida Keys bonefish PSAs. First, Boucek and his team have to catch lightning in the bottle. Carts and horses can wait.

In 1970s and ‘80s, Keys guide Eddie Wightman knew of more than a half-dozen places on the ocean side of the Keys where bonefish would school in groups of 500 or more fish. It was always during colder weather; he could nearly predict when they would show up. He’d run his boat upwind and pole down to the mass of bones, trying to point his angler in the right direction.

“I would tell my client: You see that giant cloud shadow?” he recalls. And he would wait till their hat bills pointed true.

“The cloud shadow,” he would say, “is the bonefish.”

Those were bonefish PSAs; Wightman and others are sure of it. And somewhere off the Florida Keys, the cloud shadows may still lie on the water. No one knows what draws the bonefish, what ineluctable prompting pulls them towards the deep chasms that drop off the flats. Perhaps it’s a certain sort of ocean floor upwelling, or some subtle ocean current or gyre that spins just offshore. But the fish respond to something: They stream over the flats for hours, in wave after wave. A school of 50. A school of 200. Minutes later, more. The aggregation builds into a mindboggling mass until the school makes its move to deep ocean, and dives hundreds of feet below the surface to spawn.

An acoustically tagged bonefish is released.

Ian Wilson

There could be many somewheres-out-there. Or there could be none. But there is now, for the first time, a strategic means to find them.

“There are very few opportunities for discovery on this scale,” says Boucek. “The thought of finding something that people haven’t observed for over 20 to 30 years is exciting, and even more so when you consider that it could have meaningful conservation implications down the road.”

He’s quiet for a moment, considering the next phase of the search.

“And what’s amazing is that they are hidden in plain sight,” he says. “My office looks out over the water, and for all we know, one could be right there.”

An award-winning author and journalist, T. Edward Nickens is editor-at-large of Field & Stream and a contributing editor for Garden & Gun and Audubon magazine. His latest book, The Last Wild Road, published by Lyons Press, is available now. Follow him on Instagram @enickens.