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New Weapons in the War on Lionfish, a Beautiful but Deadly Invader

Lionfish are decimating valuable native species in the western Atlantic Ocean, but spearing the predators hasn’t been enough to slow their spread. Now scientists and fishers are developing traps and other technology to catch the voracious fish en masse.

Written by Alastair Bland Published on Read time Approx. 7 minutes
An invasive lionfish in front of a curtain-style trap, a first prototype tested by Gittings.Steve Gittings/NOAA

In the driveway of his suburban home in Maryland several years ago, Steve Gittings started assembling a contraption made from a pile of rebar, nylon netting, plastic lattice and plenty of zip-ties.

Today, he wants to see his invention – a large fish trap, big enough to enclose a person but intended for a small but lethal fish – deployed throughout the Caribbean Sea and the Gulf of Mexico.

The traps are aimed at lionfish – non-native invaders introduced to Florida waters 30 years ago that have since proliferated to pestilent levels and unleashed an ecological crisis that is only getting worse. Lionfish are hated by fishers and ecologists alike because they eat the prey of commercially and recreationally valued native fish, such as snappers and groupers. Dwelling in and around coral reefs, they also put additional stress on already struggling ecosystems by killing fish that would otherwise help keep algae growth in check on a healthy reef.

With a halo of feather-like fins around striped bodies and venomous spines, lionfish are small and visually striking predators that have aggressively moved into waters from North Carolina to Venezuela and as far east as Bermuda, reproducing prolifically. Native to the Indo-Pacific region, they have few, if any, predators in the Atlantic Ocean.

A second trap design from Gittings. Lionfish are attracted to the structures inside. (Steve Gittings/NOAA)

Gittings, a scientist who works for the National Oceanic and Atmospheric Administration (NOAA)’s National Marine Sanctuary System but who has funded his project mostly on his own, is one of many biologists, divers and fishers hoping to take the war on lionfish up a notch as the fish continue to spread. Until now, divers using simple pole-spears have been marginally effective at keeping the fish at bay in the shallower waters of their newly established range.

But lionfish are increasingly moving into waters as deep as 300m (1,000ft), where they threaten fish such as snappers and wrasses. In deep waters, Gittings said, hook-and-line fishers occasionally catch lionfish, but not enough to effectively control populations. That, he said, is why fish traps designed specifically to catch lionfish may be the only viable option for keeping them in check.

“Divers are pretty effective up to about 130ft [40m], but boat fishermen with traps will be most effective in the 150–250ft range,” said Gittings, who has been tracking the lionfish crisis for years and has been collaborating with two nonprofit groups – Coast Watch Alliance and Lionfish University – to develop an effective trap.

Lionfish have been invading the Atlantic Ocean for the past 30 years. (Julie Bedford, NOAA PA)

Gittings’ trap is not yet approved for use, just for small-scale testing. In fact, no lionfish traps have yet been permitted. For any proposed trap design to be green-lighted by regulators, it must meet a variety of criteria, he said, including not disturbing or damaging the seafloor, catching little or no unintended species and posing minimal risk of entangling sea turtles and other marine animals.

These kinds of lionfish traps are now undergoing an exhaustive federal environmental review process to consider the bigger picture: how many traps could be allowed where and what the unintended or negative impacts might be. Some conservationists, for example, worry too many traps may disrupt sandy bottom habitats on the ocean floor or get lost at sea during storms. The review process, which includes seeking written public comments, is mandated by the National Environmental Policy Act. When it is completed, NOAA could decide to consider individual applications for what are called exempted fishing permits, which would open the door for fishers to use the traps commercially and sell their catch. Regulations would still apply to how, when and where the fishing gear could be used.

Lionfish – members of the scorpionfish family – have long been popular display items for saltwater aquariums, and scientists believe that sometime in the 1980s, captive individuals of two closely related species were released into the waters off the coast of Florida. In 2012, research published in the journal PLOS One found that lionfish colonization correlated with a 65 percent decrease in biomass of dozens of native fish commonly eaten by lionfish. The authors of that study called the lionfish takeover “a marine predator invasion of unparalleled speed and magnitude.”

In places, swarms of them cloud coral reefs. Joe Glass, the founder of the organization ReefSavers, which is dedicated to controlling the lionfish, is a recreational diver and spearfisher all too familiar with the invader. He described a sunken airplane in about 27m (90ft) of water off the coast of northeastern Florida that has become a popular site among scuba divers for spearing lionfish.

“You can get 500lb [225kg] of lionfish on a single dive and clean out the wreck and come back two or three weeks later and do it again,” Glass said. Aggressive spearfishing, he noted, cannot control them.

Gittings’ trap resembles a giant mesh change purse. Dropped from a boat, the device’s hoop frame pops open like two giant jaws when it hits the seafloor. The frame and the mesh lie flat on the bottom while a piece of plastic lattice, suspended over the opened net, attracts inquisitive lionfish, which tend to gravitate toward any structural objects on the seafloor. Many creatures may visit the trap, but Gittings said that while other reef fish tend to come, then go, lionfish more often come and remain over the flattened-out net until a dozen or more may be gathered around the lattice.

Gittings’ trap closes only when a boat retrieves it. That way it won’t be dangerous to fish if the trap is lost in a storm. (Steve Gittings, NOAA)

“Other fish are attracted to it also, but lionfish are really the only fish that come and stay on my trap,” said Gittings, who has shot video of his device luring in lionfish and, when lifted from a boat via the pull of a rope, closing securely around them.

The invention has proven effective in tests that Gittings conducted in the Cayman Islands and off Pensacola, Florida, catching as many as 15 fish in a 10-day soak, he said.

Hundreds or thousands of his traps working constantly in lionfish-infested waters could presumably make a significant dent in the population, Gittings believes. But fully eradicating lionfish from the western Atlantic will probably not be possible. Still, the prospect of reducing numbers to ecologically tolerable levels also has others designing clever ways to catch the fish, including an underwater robot programmed to recognize, pursue, electrically shock and then swallow lionfish.

One device, designed by the Virginia technology firm R3 Digital Sciences, is meant to be fitted to something like a lobster trap. Called a fish trap extension kit, the system features a small camera, a low-cost microcontroller and a “novel algorithm” that the company’s president, Brent Roeder, explained allows it to identify lionfish. Then it opens the trap and lets the fish inside. He said other creatures would not be allowed to enter, eliminating bycatch and posing no risk if lost or abandoned.

A finished prototype has been tested in a NOAA laboratory aquarium and will move this month to ocean testing in about 90m of water off the coast of Florida, according to Roeder. Glass, with ReefSavers, has also designed a clamshell-shaped trap that he hopes to make commercially available to fishers. He submitted an application to NOAA to test the device in May 2017.

A common lionfish. (Kevin Lino NOAA/NMFS/PIFSC/ESD)

In his proposal, Glass stated he wished to have 50,000 of the traps deployed within five years. But getting the blessings of officials is taking longer than he would like. “I might go out of the country to do it,” Glass said, noting that officials from several Caribbean nations, which he doesn’t want to name yet, are showing interest in embracing the project.

One big challenge is that manufacturing the traps will be expensive – at least in the initial stages. Glass said that doing so at a large scale will require injection molding. The trap he has designed will require five individual mold casings, and to make each one in an injection molding facility will cost $500,000, he said. Once in place, though, a single set of mold casings could be used to build many traps cheaply.

Producing so many traps, though, will be profitable only if they work well and if fishers who use them have access to ready and willing fish buyers.

“For this to work, fishermen need to make more money catching lionfish than they would be doing what they were before,” Glass said.

Luckily lionfish are tasty, with mild white meat that Glass said “absorbs whatever flavors you cook it with.” The firm flesh, he said, is also suitable served raw as sashimi. Lionfish, in fact, has become such a trendy menu item that demand now exceeds the supply, according to a 2017 NOAA report coauthored by Gittings. This is primarily because most fishers don’t have the means to selectively target and land lionfish and usually catch them only when going after species such as lobster.

“Divers just can’t spear enough,” Glass said. “We need traps.”

No matter how effective the new technology being designed to catch lionfish, it’s not likely the problem will go away soon, if ever. Unless their numbers are rapidly and drastically culled, scientists expect them to continue expanding their range in Atlantic Ocean waters.

“I don’t think we’ve seen lionfish reach their full potential range yet,” Gittings said.

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