Pictures: Sharks Taught to Hunt Alien Lionfish

Lionfish: Rats of the Sea?

Photograph by Antonio Busiello

Lionfish—like those seen above off Honduras in 2010—can take over seafloor and reef habitat and establish densities of more than 200 adults per acre.

A mature female lionfish produces some two million eggs every year, and those eggs and larvae are carried far and wide by currents—fuelling an ongoing invasion.

"I call them the Norwegian rats of the sea," said George Burgess, director of shark research at the Florida Museum of Natural History. "Just like rats, they are spreading all over the world, and you can shoot them, poison them, or curse them all you want, but they aren't going to go away."

(Related: "Rat Invasions Causing Seabird Decline Worldwide.")

The predatory lionfish is especially bad news for Caribbean coral reef ecosystems, because lionfish threaten to displace native species such as snapper and grouper—especially where those species have already been reduced by overfishing.
Lionfish may also be eliminating helpful species lower on the food chain, such as parrot fish, which are grazers that prevent algae and seaweed from overtaking coral reefs.

Published April 4, 2011

Lionfish Hunting

Photograph by Antonio Busiello

A spearfisher takes aim at a lionfish off Honduras in 2010. Lionfish hunting is widely encouraged where the pesky invaders have put down roots.

"Like everywhere in the Caribbean, Roatan Marine Park is trying to find a solution, and one idea was to try to put lionfish on the menu and make people aware that they can cook and eat them," photographer Busiello said.

The fish are said to be tasty once their venomous spines are removed, and supplies in the ocean are at an all-time high. (Read about a U.S. government campaign advocating the eating of lionfish.")

"During one competition organized by the park, more than 1,700 lionfish were killed and cooked in a single day," Busiello added. "One diver with a rubber band spear gun was able to kill 60 by himself. They really are everywhere."

Published April 4, 2011

Catch of the Day

Photograph by Antonio Busiello

Dead lionfish lie on a dock in Honduras's Roatan Marine Park in 2010. The park's attempts to promote lionfish cuisine aren't unusual—the U.S. National Oceanic and Atmospheric Administration has launched an Eat Lionfish Campaign with the tagline "If we can't beat them, let's eat them!"

But, while hoping to promote a widespread taste for the fish, NOAA ecologist and lionfish expert James Morris said such efforts currently have their limits.

"The idea of eating lionfish is a promising strategy for certain areas like Florida National Marine Sanctuary or Roatan Marine Park, where we can create a targeted, labor-intensive spearfishing effort to remove them," he said.

"But the challenge comes in how you can harvest them in high enough numbers to really keep populations in check. They are not a species we can fish right now by trawling or other large-scale [commercial] methods," because lionfish tend to stay within ocean structures and so are hard to catch without demolishing reefs or rocks.

"The reality is that we have no good strategy on the table for" a commercial lionfish harvest.

Published April 4, 2011

Friend, or Food?

Photograph by Antonio Busiello

Two sharks ponder a possible meal of lionfish in the Honduran marine park in 2010. Divers are working on a plan to get the native predators to feast on the invasive lionfish.

"At the beginning, the divers just killed lionfish and fed sharks with them to get the sharks to develop a taste," said photographer Antonio Busiello, who observed the process in action.

"In the second step, to have the sharks develop an interest in hunting them, divers started to leave wounded lionfish so that the sharks could taste them. After a while, [the sharks] did start to hunt them and go after them."

Living up to their voracious reputations, many sharks can eat venomous prey, such as lionfish, and suffer no apparent ill effects, according to the Florida Museum of Natural History.

(Related: "Sharks Are Color-Blind, Retina Study Suggests.")

Published April 4, 2011

Lionfish Nom

Photograph by Antonio Busiello

Mouth agape, a shark makes a meal of a lionfish in Roatan Marine Park in 2010.

"Certainly many species of fishes, including sharks, are trainable," said the Florida Museum of Natural History's Burgess.

"There have been plenty of studies that have been done over the years in training sharks to do various acts, and of course the ultimate training that we've seen is in feeding situations where divers feed animals so that they anticipate the food and are found in abundance at feeding sites."

But Burgess and NOAA's Morris both doubt such limited efforts can make much of a dent in reducing well-established lionfish populations.

"The effects of training animals locally are not really ecologically relevant until we find that those predators are in fact preying on lionfish on their own, without human intervention," Morris said.  "We hope that one day we will document a natural predator [in the region], but as of yet we haven't found any that have been feeding on lionfish consistently."

Published April 4, 2011

Lionfish To Go

Photograph by Antonio Busiello

One less lionfish called Roatan Marine Park home after this shark's snack—but is training sharks to feast on the fish the best way to make a difference?

"It may be more effective for the Roatan divers to spend their time hunting lionfish, as the sharks they are feeding are likely residents and not transients [so they] may only consume lionfish where the divers are already feeding them lionfish," said shark expert R. Grant Gilmore, Jr., of Estuarine, Coastal and Ocean Science, Inc., a private environmental firm in Vero Beach, Florida.

"Foraging theory states that an organism will eat food that gives [the forager] the most benefit without spending much energy finding and consuming the food.

"A lionfish in hand is easier to find and consume than one under a rock ledge. A school of grunts or snapper would likely be more accessible to the shark than a lonely lionfish."

Published April 4, 2011

Shark Dive Bomb

Photograph by Antonio Busiello

Still sporting a hook from a battle with illegal fishers, a shark in Roatan Marine Park dives toward a live lionfish just before devouring the animal—without any prompting from humans.

The shot shows exactly the kind of hunting behavior that those involved with the Roatan project hope will catch on.

"What we're hoping to see is sharks getting a taste for lionfish and actually hunting them on their own without any human intervention," said Ian Drysdale of Healthy Reefs, a conservation collaboration dedicated to measuring the health of Mesoamerican reefs.

Local humans will also be doing plenty of lionfish hunting, Drysdale added. Though many harpoons and spears are illegal under Honduran fishing laws, the park has acquired an exception to arm trained and licensed divers with fishing spears called Hawaiian Slings, for taking aim at invasive lionfish.

Published April 4, 2011

Messy Eater

Photograph by Antonio Busiello

Pieces of an unidentified meal drift from the toothy mouth of a shark off Honduras.

While it appears that lionfish in Caribbean, U.S. Southeast, and Gulf of Mexico waters are there to stay, the same can't always be said for some local species—including the sharks themselves.

Many shark populations are down significantly, and the animals remain vulnerable to fishing for fins, which are a delicacy worth U.S. $25 to $30 each, right off the boat, the Florida Museum of Natural History's Burgess says. (Related: "Shark Fins Traced to Home Waters Using DNA—A First.")

"The reality is that the intent is noble and the unity with which people are addressing [the lionfish problem] is very desirable," he said.

"I just wish we could do management of lobsters and queen conch and sharks with the same zeal and international cooperation that we're getting on the lionfish problem. Maybe we could get some of those stocks back up to where they should be."

Published April 4, 2011