Skyward leaps, violent head-shaking, gill-rattling temper tantrums and those magnificent tail-walking tirades define the tarpon attraction. Combining the brute force of an NFL linebacker with the grace of an Olympic gymnast, Megalops atlanticus brings a game that anglers and fishery managers are equally passionate about preserving.
Now, combining efforts for this common goal has never been easier, thanks to the Tarpon Genetic Recapture Study. A joint research project between Florida’s Fish and Wildlife Research Institute (FWRI) – a branch of Florida’s Fish and Wildlife Conservation Commission – and Mote Marine Laboratory in Sarasota, the study leverages forensic technology and involves recreational anglers in the process.
The CBS drama Crime Scene Investigation (CSI) has taught many of us non-scientific types that DNA provides a rock-solid identification for an individual. Each creature’s DNA holds a unique genetic code that never changes, so sampling will always provide an undeniable name tag for the fish known as the “silver king.”
That’s what the Tarpon Genetic Recapture Study is all about. Headed by FWRI research scientist Kathy Guindon, the study collects DNA samples in two ways: clippings taken from dorsal fins and skin cell samples obtained from abrasive pads rubbed against a tarpon’s bony check plates.
In the interest of tarpon safety, FWRI scientists prefer to handle the fin clips, but recreational anglers provide most of the DNA “scrubs.” In either case, a simple act secures timeless information.
Mote biologist Carole Neidig summarizes: “One (sampling) is enough to know that fish forever.”
What they’re seeking
Officially launched in 2006, the FWRI/Mote partnership is steadily building a database of details on individual tarpon catches – location, date, etc. Comparing DNA samples from past and future catches provides a definitive picture of which fish are recaptured. Such information is vital because the tarpon’s highly migratory ways, plus its extremely challenging nature makes it a more difficult species to study than other common inshore targets like snook, redfish or spotted seatrout.
According to Guindon, sonic transmitters attached to tarpon through 2007 have proven that 87 percent of the fish survive catch-and-release. Understanding what happens post release stands ever intriguing.
“Tarpon are hardy fish and the data shows that they do survive after being released,” Guindon said. “The next question is: ‘If most of these fish survive how many are caught again and where?’ We’re now looking at this so we can start to see the recapture rates and movement.”
Noting the relatively low level of lifestyle data available for tarpon, Guindon said that Florida – the state where tarpon fishing ranks highest – is particularly interested in learning more about the fish’s spawning habits. Discovering the species’ annual travel schedules may lead to cross-border management efforts.
“There are a lot of unknowns about tarpon,” Guindon said. “Just because Florida is doing a good job of managing our fisheries, it doesn’t mean that other areas in which these fish are caught are being managed properly. For example, we know that tarpon are fished commercially in some Central American waters, so we’d like to know if some of the fish we release in Florida end up getting caught (in those areas).”
How it works
The benefits of genetically tagging tarpon are many. Foremost are these:
All sizes: The study’s slogan “Any Tarpon, Anywhere, Any Size” says it all. Neidig points out that the DNA method opens the study to more fish than conventional dart tagging. “Genetic sampling allows you to take DNA from any size tarpon, whereas we wouldn’t have used conventional tags for smaller fish. You can go ahead and take that sample and we’ll know that fish forever.”
No pain, big gain: A tarpon’s bony cheek plate has no blood vessels, so scrubbing there is a low impact operation with no risk of infection. “Genetic tagging is less invasive (than conventional dart tagging),” Guindon said. “It’s no different than if a tarpon rubbed against a rock or ledge under water.
“If you put a conventional tag in a fish, it can develop a sore, the tag can fall out or it can become degraded by the environment. For years, that’s all we had, but now that this (DNA) technology has developed, it’s the wave of the future.”
Quick and simple: For anglers in flats and bay boats, taking DNA scrubs requires no more effort than reaching over the side to remove a hook and revive the fish. In boats with more freeboard (higher sides), anglers often attach a scrub pad to a mop handle for longer reaches.
Maximizing resources: Noting that FWRI can work up a tarpon DNA sample for about $3, Neidig said: “It’s a lot more reasonable for us to do this than to purchase tags. It’s a very cost-effective method and with the anglers helping us collect the samples, that helps drive the cost down even more.”
How to participate
Guindon said she occasionally receives DNA samples from anglers in the Carolinas, Georgia, Mississippi, Louisiana and Texas. Internationally, scrubs have come from Mexico, Guatemala, Costa Rica, Belize, Trinidad, Puerto Rico, Angola, French Guiana. Wherever the silver king roams, anglers are welcome to participate in the Tarpon Genetic Recapture Study.
If you catch a tarpon, rub his cheek, submit the DNA sample and go tell your friends you are now a forensic contributor. Although FWRI can’t guarantee you a CSI cameo, your contribution to tarpon research will be irrefutable.
“The anglers are playing the part of scientists,” Neidig said. “There’s no way we can cover the entire state by ourselves. The anglers who have helped us have said they enjoy it. We’ve even heard of (unofficial) competitions between anglers to see who can turn in the most samples.”
Mote and FWRI award random monthly prizes for tarpon DNA sampling participation and year-end prizes based on volume. Several tarpon tournaments include the sampling in their format. The Suncoast Tarpon Roundup in Tampa Bay requires DNA samples as proof of release, while the Silver King Classic in Fort Myers offers a special prize division for voluntary participation.
In Boca Grande, the Pro Tarpon Tournament Series does not require competitors to sample tarpon, but anglers releasing fish for points often grab a quick DNA scrub, while those who opt to weigh fish in the PTTS committee boat’s sling scale typically allow Guindon to take a fin clip before sending the fish on its way.
“We don’t force teams to participate, but we encourage it,” Mercurio said. “Our anglers have the option to allow (Guindon) to take the DNA samples when they weigh their fish and we have never had anyone turn her down. That’s a testament to all the anglers fishing our events that they are dedicated to preserving the tarpon populations for the future.
“The only thing about genetic tagging is that there’s not the instant gratification of ‘Oh, there’s a tagged fish.’ We use this as a challenge to the anglers by telling them to take a DNA sample of every fish, because the one you sample may be a DNA tagged fish.”
FWRI provides sampling kits with scrub pads, plastic vials with ethanol for preserving the samples, catch data sheets, pencils and zippered plastic bags for returning the samples to official drop-off sites. No refrigeration is necessary and drop-off sites can also provide additional sample kits.
Of course, participation requires tarpon capture, so whether you’re floating live threadfin herring on a quiet beach, free-ling baits near bridge pilings, drifting pass crabs on an outgoing tide, soaking dead menhaden near rocky bottom, or presenting a rabbit hair fly at just the right moment, your next silver king has an appointment with forensic science.
For information on genetic tagging, call (800) 367-4461 or email TarponGenetics@myfwc.com.
