Native to the Indo-Pacific, the beautiful but invasive lionfish is wreaking havoc on Caribbean reefs. Many nations, including the Cayman Islands, have resorted to lionfish culling to address the problem.

I saw my first lionfish during my open-water diving course in Koh Tao, Thailand. The instructor was excited — it was a rare sighting. Not so in the waters of many Caribbean islands today. These fascinating fish feature characterful faces with jutting lips and a mane of sharp, poisonous spines. Air sacks even allow them to hang upside down within a cavern. But their beauty is deceiving, at least in Caribbean waters: invasive lionfish have become a gigantic problem on many, if not all, of the region’s reefs. Native to the Indo-Pacific, these invaders threaten the Caribbean ecosystems which they have overrun. To help address the problem, lionfish culling has taken hold across the region, including in the Cayman Islands.

Lionfish arrive in the Cayman Islands

Divers first spotted red lionfish in the Cayman Islands in 2008. It has since spread rapidly throughout the region. It’s unclear how they first got here, but lionfish tracking suggests that the problem began in Miami. Theories range from deliberate pet disposal into the sewers to aquarium damage from hurricanes.

In the Caribbean, the lionfish, like many accidentally or deliberately introduced species, has no natural predators. Starting when they’re one year old, female lionfish can release between 10,000 and 30,000 unfertilized eggs every four days, year-round. They are voracious predators. They can consume prey up to just over half of their own body size, and their stomach can expand up to 30 times its normal volume. Divers and researchers have found dead lionfish with dozens of small reef fish in their stomachs. This combination of reproductive frequency and insatiable appetite has led to an explosion in lionfish populations across the Caribbean.

Lionfish culling

Cayman’s first response was the Lionfish Rapid Response Task Force, which encouraged divers to catch lionfish alive in nets, to be finished off by a dive knife or studied further. But with 18 venomous spines across the back, dorsal, pelvic and anal fins that contain a neuromuscular toxin that can necrotize the flesh of a diver or swimmer who touches them, the plan soon changed.

By the time I joined the Task Force, the thinking had evolved. It is illegal to import spear guns into Cayman because the government is keen on marine preservation, although some historic guns that belong to local families are floating around. The Department of Environment prevailed upon the government, however, to allow the import of some Bermudian sling spears. The spears are two-foot-long, three-pronged poles, with a rubber band that propels the spear from your hand to impale a fish.

Bermudian sling spears are not the most accurate, and divers must get quite close to avoid the lionfish’s quick response times. Despite seeming sedate, they can move remarkably quickly, their spines pulling back like a dog’s ears. They can disappear into the ironshore’s cracks before you have chance to hit them. Willing volunteer recipients watched a video explaining the lionfish menace and obtained a police-clearance certificate to receive one of the spears before lionfish culling began.

Recruiting local predators

Initially, the DOE tried to encourage local predators, primarily grouper and snappers, to eat lionfish. Divers fed them dead lionfish from the spear tip, hoping that they would develop the instinct to hunt lionfish. So far, snappers and grouper will gobble lionfish up off your spear and clearly like them, but haven’t begun to hunt the fish themselves. Instead, these predators have learned that divers sometimes provide food and now follow them looking for a handout on several dive sites. Nurse sharks even join on a few sites, like bloodhounds on the hunt.

They aren’t the only sharks who show an interest, and it is now a rare lionfish culling dive on the East End of Cayman that doesn’t see a reef shark investigating what we’re up to. As the sharks have become more inquisitive, even daring to take a lionfish or two off the spear, the culling ends when we first spot the sharks. Because of the shark presence, only dive staff culls some of the sites.

What next for lionfish culling?

The increased shark interactions mean we can no longer feed lionfish to smaller predators. The DOE is rethinking its strategy of handing out spears, and volunteers must now capture lionfish in opaque containers, often homemade from old water containers. A funnel provides a valve for trapping the fish.  Even before this directive, most divers took containers on culls because lionfish is a firm white fish that’s tasty in ceviche or when grilled.

Local dive shops and businesses, including a local supermarket chain, arrange regular lionfish culling trips in exchange for a subsidized dive.  The Cayman United Lionfish League runs regular culling competitions. These promote culling and eating lionfish to put to good use mankind’s knack for wiping out species that they find tasty. Restaurants on island promote various dishes involving lionfish, popular among both tourists and locals.

The culling appears to be having a positive effect. Divers rarely see lionfish on common dive sites, and culling trips are returning smaller hauls. When I started culling on the East End, a boat of divers would catch 150 to 200 lionfish. Now we return with 80 to 100. In the west, the lionfish are certainly cannier. Those that have had a close call in the past are wary of divers. They will often slink into a crevice before you can get within range. As their numbers have fallen, dive shops will occasionally anchor in sandy patches that have sometimes never been dived before, hoping to find a motherlode of lionfish.

However, it’s a case of trying to hold back the tide. While we see fewer lionfish at recreational diving depths, it seems they are just going deeper. The problem spans the entire region as well. Diving in Cuba a year ago, I spotted several lionfish. They’re breeding there without restriction, along thousands of miles of coastline. The epidemic has already taken a terrible toll on Caribbean diving generally.

What can you do?

So, what can you do? Many Caribbean dive centers offer culling courses. Even if you cannot get a spear due to local restrictions, you can spot for the cullers. But it’s not just the diving that helps. Ask for lionfish in restaurants when visiting and source them in your local supermarkets. Make sure of course that they’re not from the Indo-Pacific, where they belong. This will help generate revenue and interest beyond enthusiastic divers who are trying to do their bit. Our propensity to wipe out species through greed can finally be put to good use.

On the flipside, you can help avoiding any other fish caught in the Caribbean, or eating fish in general. If you must eat seafood, please stick to so-called sustainable species.  Taking fresh fish from the ocean is wiping out stocks that are not meant purpose. Every grouper, snapper, or parrotfish on the menu is one that could be breeding in the sea and replenishing stock that the lionfish are diminishing.

By guest author Jez Snead

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