Invasive Lionfish Are Such Effective Predators They’re Becoming Obese

Unfortunately, so far local human populations haven’t taken to eating the invasive, piggy lionfish out of existence

Christian Mehlführer

In waters stretching from the U.S. East Coast into the Caribbean and Venezuela, the venomous, aggressive lionfish takes the prize for most destructive invader. Some researchers believe it even ranks among the 15 biggest threats to all species worldwide. At Slate, Christie Wilcox reports on the decimation that this species can reap when it arrives at a new reef:

When lionfish arrive on a reef, they reduce native fish populations by nearly 70 percent. And it’s no wonder—the invasive populations are eight or more times as dense than those in their native range, with more than 450 lionfish per hectare reported in some places. That is a lot of lionfish….

They’ll eat whatever they can get their mouths around, which happens to be any fish or invertebrate just a hair smaller than they are, and they can grow to more than 18 inches long.

All of that eating, it turns out, has caught up with the lionfish. Lionfish caught off the coast of North Carolina, expert James Morris told Slate, are becoming obese. The fish often contain so much body fat, Wilcox says, that their livers appear to be suffering for it.

So far, lionfish dissections in North Carolina have revealed the remains of around 70 different species chewed up within the predators’ guts. A study in the Bahamas found that lionfish eat around 1,000 pounds of prey per acre per year, Wilcox writes. But the North Carolina team has reason to believe that obese lionfish are actually overeating beyond what they need to survive:

Though lionfish can go weeks between meals, when they don’t have to, they won’t. Scientists have observed lionfish eating at a rate of one to two fish per minute, and their stomachs can expand 30 times their size to accommodate lots of food. To become obese, fish eat upward of 7.5 times their normal dietary intake, which means the abundant North Carolina lionfish could be eating as much as 7,000 pounds of prime North Carolina seafood per acre every year—seafood that we’d much prefer ended up on our plates instead.

Lionfish aren’t the only species besides humans overeating, either. Zoo elephants are increasingly obese. The National Zoo put one bear on a diet. Lab animals are gaining weight, as are house pets. But none of those animals are destroying whole ecosystems to feed their already-full tummies.

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