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If you can’t beat ’em, eat ’em

There’s a growing trend among scuba divers in the Caribbean: they’re on the hunt for something tasty…

Last month, the Glass Goby (Coryphopterus hyalinus) suffered a change in status on The IUCN Red List of Threatened Species. Previously considered of Least Concern to conservationists, this reef-dwelling fish is now listed as Vulnerable. And it isn’t alone. The goby family is huge – having more than 2,000 (mostly) miniscule members – and of the 143 Caribbean gobies that marine biologists have just now assessed for The IUCN Red List, nineteen species are in danger of going extinct. One of these, the Vulnerable Peppermint Goby (C. lipernes) is a widely distributed, but uncommon species, and a population decline of over 30% is predicted over the next ten years.

 Lazlo Ilyes
Habitat degradation and predation by the invasive lionfish are expected to drive down the Peppermint Goby’s population by more than 30% over the next decade. Photo courtesy of Lazlo Ilyes

So who darkens the doorstep of these diminutive demersals? If we go chronologically, the trouble begins with coral reef degradation and destruction, which since 1979 have reduced reef coverage in the Caribbean region by a whopping 59%. And in the mid-1980s, a second culprit arrives just in time for dinner.

No one knows for sure how the fierce and eerily elegant lionfish (Pterois volitans and P. miles) made their way from the Indo-Pacific to the Florida Keys, where they were first documented in 1985. But there are clues: lionfish are a popular saltwater aquarium pet, and their genetic diversity in the Caribbean today is small. The popular theory is that several decades ago, one or more Floridians released a few pet lionfish into the sea, and the rest is history.

With venomous spines, lionfish have few natural predators in their native habitat. Pterois volitans, which makes up approximately 93% of the invasive lionfish population, is also commonly called the 'red lionfish' and P. miles is often called the 'common lionfish' or 'devil firefish'. Photo courtesy of Pierre Malo.
With venomous spines, lionfish have few natural predators in their native habitat. Pterois volitans, which makes up approximately 93% of the invasive lionfish population, is also commonly called the ‘red lionfish’ and P. miles is often called the ‘common lionfish’ or ‘devil firefish’. Photo courtesy of Pierre Malo.

This introduction of lionfish into the Caribbean region and western Atlantic has been called the worst biological invasion caused by mankind in, well… the history of man. Lionfish are eating whole reefs alive: one experimental study found that in as little as five weeks, a single lionfish was able to reduce native fish recruitment (the number of larvae becoming adults) by 79% within its range. And the invasion is still spreading; as far north as New England and as far south as Brazil.

The list of offenses goes on: lionfish hunt indiscriminately and can consume other animals as large as 60% their own body size; their stomach volume can expand 30% to accommodate their gluttony; and females can spawn up to two million eggs per year (and can live for fifteen years)! On top of their voracious appetite and impressive fecundity, native Caribbean and western Atlantic species seem not to recognize them, either as predator or as prey. Small fish are sometimes seen ‘sheltering’ among the lionfish’s long spines, apparently unaware of the imminent danger. And while there is some evidence that sharks, groupers, and other large predators will eat lionfish, it is likely that their unique anatomy precludes most predation. Their long, venomous spines and bold stripes – traits uncommon amongst native fishes – are either confounding or discouraging, or both.

GlassGoby_VU
Lionfish now occur throughout the range of the glass goby (Coryphopterus hyalinus). Despite being more common than the Peppermint Goby, the Glass Goby is likewise predicted to decline over 30% across the Caribbean in the next ten years, thanks to lionfish predation. Photo courtesy of Mike Cisek.

One class of hunter, however, is grateful that lionfish are so conspicuous: scuba divers, many armed with spears called Hawaiian slings. There are scientific researchers who hunt or capture lionfish to gain a better understanding of their biology and behavior. There are community groups and tourists, who relish the sport as much as they value conserving reef ecosystems. And there are those – including Caribbean restaurateurs – who also recognize that lionfish are a true delicacy.

Lionfish are voracious hunters, known to consume more than 50 other species of fish in the Eastern Atlantic and Caribbean regions. Combining lionfish harvest programs with a change in fishery management practices to sustain high numbers of native groupers (subfamily Epinephelinae) may allow the ecosystem to return to a state where harvest of native species once again becomes practical. Photo courtesy of Andy Phillips, Utila Dive Centre, Utila, Honduras.
Lionfish are voracious hunters, known to consume more than 50 other species of fish in the Eastern Atlantic and Caribbean regions. Combining lionfish harvest programs with a change in fishery management practices to sustain high numbers of native groupers (subfamily Epinephelinae) may allow the ecosystem to return to a state where harvest of native species once again becomes practical. Photo courtesy of Andy Phillips, Utila Dive Centre, Utila, Honduras.

Targeted and repeated lionfish removals may be a viable management option to protect ecologically important species, but most experts agree that fishing will never eradicate the invasion. One model predicts that annual removal rates of 15–65% are required just to reduce localized lionfish populations. And so numerous organizations and government bodies are encouraging divers to harvest lionfish. The National Oceanic and Atmospheric Administration ran the Eat Lionfish Campaign in 2010; the International Coral Reef Initiative is urging Caribbean countries to adopt a regional roadmap to control the lionfish; the Reef Environmental Education Foundation hosts ‘Lionfish Derbies’ (offering prize money for largest, smallest, and highest number caught) and publishes the Lionfish Cookbook; the Central Caribbean Marine Institute and the University of Florida co-manage the Little Cayman Community Cull; and in 2013 the Florida Fish and Wildlife Commission waived the license requirement for catching lionfish with certain gear types and eliminated the catch limit.

Lionfish is considered a delicacy due to the appeal of sustainable eating as well as the fact that the method of catching lionfish is labor-intensive and challenging: diving for them with spears instead of fishing with a rod or net. Photo courtesy of Kayleigh Hyslop and Katherine Blackwood.
Lionfish is considered a delicacy due to the appeal of sustainable eating as well as the fact that the method of catching lionfish is labor-intensive and challenging: diving for them with spears instead of fishing with a rod or net. Photo courtesy of Kayleigh Hyslop and Katherine Blackwood.

Recreational diving is a booming sub-sector of the tourism industry, and worth upwards of $2 billion annually in the Caribbean. And despite many dive operations and scuba certifying bodies championing the ecotourism ideal and promoting stewardship among divers, recreational diving certainly carries an ecological price tag. In many Caribbean locales, access to dive sites necessitates coastal development, which in small island developing states and Central American countries frequently goes unregulated and unleashes a cascade of environmental degradation onto the very ecosystem attracting tourists. Unregulated and illegal reef fishing bolstered by rapid coastal development may even have laid the groundwork for lionfish to flourish in the Caribbean; for decades humans have overfished large groupers and other potential lionfish predators.

Sadly, scuba divers themselves can also contribute to reef degradation, especially when they stir up sandy bottoms or collide with the slow-growing coral. (The accumulation of sediment on coral tissues and injuries inflicted by collisions are both strongly linked to incidence of coral diseases.) Research conducted on Koh Tao (a Mecca for new divers in the Gulf of Thailand) revealed that coral health was dramatically poorer at the most popular dive sites than at sites with fewer boat visits per day, suggesting that better management is needed to reduce the impact of divers on coral reefs.

It appears that both the recreational diving industry and lionfish have become permanent fixtures of the Caribbean environment. The question is whether these can be sustainably managed in the interest of coral reef ecosystem survival.

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by

Katherine Blackwood, IUCN