Posts Tagged With: oceans

An attractive enemy: impaling invasive lionfish

In March, I was scuba diving off Cozumel when I heard that the dive master had speared a lionfish and fed it to an eel. Luckily, I did not see this happen. And, with no pre-dive education other than—“Don’t touch anything…we don’t want to harm the reef”—the act was shocking. Another diver told me lionfish were not native to these waters and were crowding out native species. Still, for a dive master to impale one in front of unknowing tourists, seemed extreme.

A lionfish (Pterois volitans) swims in a Caribbean reef. (Photo by Nick Hobgood)

The Mesoamerican Reef is the second largest barrier reef in the world. It stretches from the top of Mexico’s Yucutan Peninsula past the beaches of Belize, Guatamala, and Honduras. Its waters contain a rich ecological diversity including some five hundred species of tropical fish, and several species of sea turtle and dolphin. Among this assortment swims one striking non-native species: lionfish.

According to the National Oceanic and Atmospheric Administration (NOAA), these Indo-Pacific natives were introduced into the Caribbean by an aquarium spill off the coast of Florida. They believe that the entire Atlantic lionfish population—which now stretches from Rhode Island to Colombia—spawned from this handful of individual specimens that entered the ecosystem in 1992, during Hurricane Andrew. The lionfish infiltration of the Atlantic Ocean and Gulf of Mexico is alleged to be the largest of all predatory invasions the oceans have yet encountered.

Lionfish are an attractive enemy. But the long orange, black, and blue spines that elegantly swirl out from their stripes are venomous; they use them to strike cornered prey. Lionfish are demonized as aggressive predators. Some of the fish they eat are important to the coral reef system, as they thin seaweed and clean algae from coral. If these herbivores decrease, the reef itself—an ecosystem already made fragile by global warming—will change. In the waters off the Bahamas, their voracious appetites have reduced coral reef fish populations by about eighty percent. Part of the problem, scientists speculate, is that fish native to the Atlantic Ocean do not know lionfish are predators and are not quick to recognize the danger of its approach.

Lionfish appear to spawn year-round and can lay as many as one thousand egg sacs every week. What’s more, they don’t have natural predators in the Caribbean. Grouper have been known to prey on them, but the popularity of grouper as a food fish makes it unlikely their numbers could control the invaders. Experiments are on-going. Scientists believe if larger species acquire a taste for lionfish, the problem could be controlled. Thus, they feed them to sharks and moray eels, and have afterwards observed these animals going after their own lionfish. This is the type of population control effort I nearly witnessed on my dive. (An unofficial program, from what I can discern.)

Humans, we are told, could also learn to love lionfish cuisine. They are enjoyed in dishes near their native waters, in China and Indonesia. Some Caribbean communities have organized lionfish hunts, followed by experimental barbecues. Chefs at gourmet restaurants are even beginning to dream up dishes to entice fine diners. Some say its taste and texture resembles halibut. Lionfish might even be classified as sustainable seafood since their deaths are considered a victory for the reef’s ecosystem.

Often introduced by human movements or accidents, invasive species are a problem around the world. But the question remains: Should we interfere again to undo what we have done? What happens, for example, if sharks and eels become reliant upon lionfish as food and they are then eradicated? What if predators begin to devour so many lionfish that the populations of their former food sources explode? Does trying to restore an historical balance upset other relationships?

Virgin Islands National Park diver Devon Tyson examines a lionfish captured in the park's waters.

In last week’s New York Times Sunday Opinion section, anthropologist Hugh Raffles commented smartly upon cultural attitudes about human and ecological immigration. Throughout history (and in America especially) he asserts, “our natural landscape is a shifting mosaic of plant and animal life…Designating some as native and others as alien denies this ecological and genetic dynamism.” The problem of invasive species, Raffles argues, has as much to with cultural perception as scientific analysis. “It draws an arbitrary historical line,” he concludes, “based as much on aesthetics, morality and politics as on science, a line that creates a mythic time of purity before places were polluted by interlopers.”

The fact is, the invader is already there. Things have already changed. Scientists have good reason to worry about the reef given the changes they have already observed. But does more change create more problems? Which moment in history represents a system’s “natural” and “native” state? Or, as Raffles suggests, is such a thing merely a myth of purity we create to fend off the unfamiliar?

Resources:

The Nature Conservancy

REEF

NOAA

Additional References:

Daily Barometer

Huffington Post

Categories: Animals, Nature | Tags: , , , , , , , | 3 Comments

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