Tagging Giant Trevally in the Seychelles

Known as “the gangster of the flats,” the giant trevally is the most sought-after gamefish in the Seychelles. A tagging expedition on Alphonse Island aims to uncover more about this apex predator’s critical role in the ecosystem.

The Republic of Seychelles comprises 115 islands 900 miles off the east coast of Africa, 1,800 miles northeast of Madagascar. The Seychelles is world renowned for its saltwater fly fishing, and there’s no better place to experience it than Alphonse Island, a five-star fishing lodge in the outer islands.

Giant trevally closeup
The giant trevally is the most sought-after gamefish in the Seychelles.Courtesy SFTV

To better protect and sustain this extraordinary fishery, Alphonse Island has launched a research project to tag and track giant trevally. As the apex predator of the flats, a healthy GT population is essential to a healthy ecosystem. Earlier this year, Sport Fishing Television was invited to document the latest tagging effort.

Seychelles from the air
The Seychelles is among the most remote and environmentally protected countries on earth. The majority of the islands are uninhabited, and more than 50 percent of the total land area is under natural conservation. Alphonse Island builds on that ethos. It’s a self-sustaining resort (solar-powered, plastic-free, garden that generates two tons of produce per month) with private access to three atolls — underwater volcanoes with coral growing on top.Courtesy SFTV
Fish around Alphonse Island
Alphonse Island is pristine. Scuba divers enjoy visibility up to 150 feet. It’s home to a wide variety of marine life, from angelfish to permit to sharks to manta rays. Anglers have caught upwards of 60 different species on fly in one week.Courtesy SFTV
Alphonse Island is secluded
Alphonse Island doesn’t experience the same pressure as the flats of the Bahamas or Belize. Part of the reason is its remote location (21 hours flight time from the U.S.). It’s also due to the fishing regulations. St. Francois, one of Alphonse Island’s three atolls, boasts 10,000 acres of white-sand flats, and the lodge only allows 12 anglers per day.Courtesy SFTV
Giant trevally off Alphonse Island
The most sought-after species on Alphonse Island is the giant trevally, known as the “GT” or “jeet” to anglers familiar with them. Alongside sharks, GTs rule the flats. It’s a carnivore known to reach speeds of 35 miles per hour.Courtesy SFTV
Tagging a giant trevally
Because of its critical role in maintaining a healthy, balanced ecosystem, Alphonse Island has partnered with the University of Massachusetts Amherst Schools of Fish Conservation and Marine Science to tag and study giant trevallies. The lodge is trying to better understand their movement patterns, behavior and recapture rate. Without a healthy, sustainable GT population, the ecosystem collapses.Courtesy SFTV
Fly fishing for giant trevally
For the first couple days, the hunt for GTs is fruitless. Fortunes change on the third day, during a pushing tide in the late afternoon. The atolls act like a series of lochs that fill and drain with each tidal shift. The GTs hunt for food when the channels are flooded and smaller baitfish come out to feed. Head guide Kyle Simpson spots a GT at 12 o’clock. Using a 12-weight fly rod, he drops a fly in the perfect spot.Courtesy SFTV
Fighting a giant trevally on fly tackle
The GT goes into full battle mode, pulling the 16-foot skiff through the channel. Its initial instinct is to head for coral or deeper water, which often results in a break-off. The only thing that breaks during this fight is Kyle’s fly rod, which leaves him to essentially hand-line the fish.Courtesy SFTV
Large trevally brought to the boat
The giant trevally is finally brought boat side. Kyle wades into the rushing waist-high water and secures the fish. It is the biggest GT of Kyle’s life.Courtesy SFTV
Personal record for a giant trevally
Kyle celebrates his personal record GT – approximately 50 pounds. More than 1,400 GTs are caught at Alphonse Island every year, with an average weight of 30 pounds.Courtesy SFTV
Inserting a tag into a giant trevally
Dr. Andy Danylchuk, professor of fish conservation at UMASS Amherst and lead scientist for Alphonse Island’s giant trevally research program, inserts a tag. Preliminary data shows that the GT recapture rate at Alphonse Island is very low, which points to a healthy population.Courtesy SFTV
Resort at Alphonse Island
The main fishing season at Alphonse Island runs from October to May. Along with a team of experienced fly fishing guides, guests can enjoy scuba diving, snorkeling, bluewater fishing, bird watching, guided nature tours, and all the standard amenities of a high-end resort (pool, spa, tennis courts, waterfront dining). For more information, please visit alphonse-island.com.Courtesy SFTV
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