CORE Launches a New Approach to Controlling Lionfish

This is the second of two stories about the efforts of the Caribbean Oceanic Restoration and Education Foundation, known as CORE, to save the reefs in the Virgin Islands.

Lionfish aggregating on lattice in a purse trap

In recent years, lobster fishers in the Florida Keys started noticing something disquieting: when they hauled up their traps, they were more likely to find lionfish than lobsters.

Putting their own spin on the adage, “If life hands you lemons, make lemonade,” they started delivering lionfish to restaurants, and it turned out the white, flaky meat was pretty popular.

“The demand for lionfish grew,” said Frank Cummings, president of CORE, the organization that is at the forefront of the battle against lionfish in the Virgin Islands. “Now they go full-bore lionfish trapping in Florida, and it’s great. They are still catching lobster during that season. Unlike with lobster, there is no season, and no catch limits.”

Lionfish are an invasive species in the Caribbean that have threatened the ecology of coral reefs in the Virgin Islands since 2008.

According to Lionfish Quickfacts, lionfish are carnivorous and eat more than 70 species of fish and invertebrates. “On heavily invaded sites, lionfish have reduced their fish prey populations by up to 90 percent and continue to consume native fishes at unsustainable rates,” the site states.

In Florida now, most of the lionfish are being caught at depths of between 150 and 200 feet, far beyond the range of ordinary scuba divers, and this made Cummings pause. Up until recently, CORE has been waging the war against lionfish on two fronts: by arming local snorkelers and divers with specially-adapted spear guns to patrol bays they normally frequent; and by sending out teams of divers to less accessible reefs that feature the type of habitat that lionfish favor.

“But if 99 percent of lionfish caught in Florida by commercial trap fishermen are coming from depths of greater than 150 feet, and it turns out to be the same here, that suggests all we’re getting is one percent of the lionfish out there,” said Cummings, “so you have to ask: are we having any effect?”

In the spring of 2017, Shane McKinley, a scientist with the Department of Agriculture who now also serves as the treasurer of CORE, came to Cummings with a study. It featured the work of Steve Gittings, the chief research scientist with NOAA’s marine sanctuaries.

Steve Gittings holds a model of his purse trap

Gittings had been developing designs to trap lionfish, a tricky task for several reasons. Lionfish are not attracted to either live or dead bait, but it turns out they do like “structure.” As Cummings explains it, “A lionfish likes being in an area next to a structure with its venomous spines facing outward for protection.”

Knowing this, Gittings started designing traps featuring a structure set within a circular net that lies on the seafloor. When lionfish move out of their lairs to hunt, they naturally move toward these structures, known as FADS – fish aggregation devices – and wait for prey.

Gittings’ latest design is known as a “purse trap” because when the trap is hauled up toward the surface, it closes like a purse around the FAD with the attached lionfish. Other species of fish that are nearby can easily swim away from the closing trap walls as the trap is being raised, so only the lionfish are harvested.

Cummings demonstrates how the purse traps fold

Cummings demonstrated the concept in a restaurant by folding a round, cardboard coaster in two as he raised it off the tabletop; to see the traps in action, follow this link.

Several months ago, a group of volunteers from St. Thomas and St. John started building a set of five purse traps, using a piece of lattice as the FAD in a circle of batting cage netting. On Feb. 8, they deployed two of the traps in 140 feet of water, approximately one mile north of the South Drop and one mile east of French Cap. It wasn’t the ideal location, but setting traps like this requires special permitting in V.I. waters, and this spot was available.

Cummings said a team of volunteers expects to haul the traps in a week or so, and he’s determined not to be disappointed if he doesn’t get any lionfish this time. “If we don’t catch any, we’ll know where the lionfish aren’t,” he said.

He’s got his eyes on some other sites nearer to the edge of the South Drop. The problem is that CORE doesn’t have a way to access these sites at this time. The boat that was donated to the organization was damaged in the hurricanes of 2017. As a strictly volunteer organization, CORE doesn’t have the resources to devote to expanding this research. Cummings hopes to find funding to repair the boat, buy gas, and hire a staff member who can secure grants to continue their work.

He’s eager to learn if the lionfish in Virgin Islands waters contain ciguatera, the toxin produced by a type of single-celled marine organism that leads to nausea, pain, and neurological disturbances when ingested by humans. Commonly known as “fish poisoning,” ciguatera is found in problematic concentrations in the flesh of predator reef fish that eat grazing reef fish.

Since lionfish prey on other fish, you’d expect them to have high levels of ciguatera, but Cummings said there hasn’t been one documented case of anyone coming down with ciguatera poisoning from eating lionfish. It’s not something that could be kept a secret; medical officials are required to report incidents of its occurrence to the CDC.

Cummings wonders why nobody has gotten sick from eating lionfish. It might be because ciguatera is thought to be in lower concentrations in Florida where lionfish are now appearing on menus with more frequency. Florida is north of the latitude where ciguatera is most commonly found around the globe.

If lionfish could be harvested in quantity in the Virgin Islands, and if studies indicate areas where lionfish don’t carry problematic concentrations of ciguatera, it would be a boon to the local fishing industry in two ways: first, lionfish could augment the supply of local food fish, and second, the removal of lionfish will increase the chances of our local, indigenous fish surviving.

As Cummings was describing CORE’s efforts to eradicate lionfish, he was approached by CORE volunteer Carlos DiBlasi, who was eager to tell him about a recent dive trip to St. Croix. DiBlasi told him about seeing schools of sharks swimming around him and his daughter as they dove off St. Croix’s wall. The sharks appeared to be waiting for someone to feed them some tasty lionfish, a practice that is becoming more common throughout the Virgin Islands.

Cummings was visibly alarmed.

“That is not a CORE-sanctioned activity!” he said.

If local sharks were natural predators of lionfish, as they are in some places around the world, it would be a handy solution to the lionfish invasion in the Caribbean, he said. But the last thing snorkelers and divers here need is to jump in the water and be surrounded by sharks expecting an easy meal, he said.