Environment

Invasive lionfish have huge appetites. Hotter oceans will make them hungrier, new study finds

Invasive lionfish are “eating machines” and are harmful to marine ecosystems in the Carribean, said Clay Steell, lead author of a new study that shows lionfish have bigger appetites in warmer waters.
Invasive lionfish are “eating machines” and are harmful to marine ecosystems in the Carribean, said Clay Steell, lead author of a new study that shows lionfish have bigger appetites in warmer waters.

As the ocean gets warmer, lionfish get hungrier, a new study indicates. With climate change happening now, that’s bad news for the Atlantic marine ecosystems the invasive lionfish has ravaged for decades.

Native to the Indian and Pacific oceans, lionfish were first released into the ocean as unwanted pets and can now be found off the coast of Florida and as far south as Brazil.

Lauded for their beautiful maroon and white stripes, lionfish have become the bad boys of the Carribean, wreaking havoc in the coral reef ecosystems they invade. They’re also common on Florida’s reefs and have been called the biggest threat to Florida’s fishing industry.

“They are eating machines,” said Clay Steell, who led the study for his master’s thesis at Carleton University. “They can cause local extinctions in places, they just completely remove other species of fish.”

Steell conducted his study in the Bahamas, looking at lionfish feeding behavior in winter temperatures (26 degrees Celsius) and peak summer temperatures (32 degrees Celsius). He found lionfish are able to eat 42 percent more food in the warmer water.

Fish typically expend the greatest amount of energy when swimming as fast as possible. But lionfish direct more of their energy into eating, and seem to be able to break their food down quicker in warmer temperatures.

They can invest 1.7 times as much energy into digestion than swimming, providing insight into why they are such a devastating invasive species, Steell said. That’s important when you can cram up to 30 times your own stomach volume down the gullet, as lionfish can.

They have such voracious appetites that they have been known to resort to cannibalism in some cases. Even this hardly puts a dent in their population, since lionfish crank out offspring — a mature female lionfish can spawn more than two million eggs a year.

Bigger predators generally stay away from lionfish, which have poisonous spines, allowing lionfish to treat reefs as all-you-can-eat buffets, feasting with relative impunity. Lionfish enjoy snacking on all kinds of species, including some of the most commercially viable, such as juvenile groupers, snappers, and climbing lobsters. They lure fish closer by blowing jets of bubbles at them to mimic currents, causing the fish to turn towards the lionfish and be swallowed head-first.

“They are a really big threat to marine ecosystems and animals,” Steell said. “Wherever they go there are less healthy fisheries, less for tourists to see.”

Like in the case of the invasive Burmese python, intrepid conservationists have attempted to fight back against the lionfish, motivated in part by the promise of a delicious meal.

The new study, published in the Journal of Experimental Biology this week, can help identify the best ways to remove lionfish, Steell said. It is also a step towards helping marine biologists understand the future impacts of the climate crisis on the lionfish epidemic, Steell said.

“There is a lot that the ocean gives us,” Steell said. “And all of that depends on a healthy ocean ecosystem.”

  Comments