Uh Oh. Researchers discover lots of huge (invasive) lionfish living deeper than expected

lionfish photo
CC BY-NC-ND 3.0 drocpsu

Lionfish. For anyone familiar with this species, you'll know that they have incredible appetites. That's fine when they live in the Pacific where they evolved, and their numbers are kept in check. But when they are living where they don't belong, and have no predators, their presence spells disaster.

Introduced to the Atlantic in the 1990s, lionfish have made quick work of eating everything in sight, reducing some fish populations by more than 80 percent. A serious problem for conservationists for decades, it was thought that these fish would at least be hanging around coral reefs in shallower areas, where it is easier to catch them. But researchers studying this invasive species discovered a big problem -- bigger fish, lots of them, living deeper than that many of that size were expected to be.

Though some lionfish were expected to be spotted, the number and size of those found came as a surprise to researchers from Oregon State University who recently dove down to 300 feet during a survey of the species. The researchers were the first to use a deep-diving submersible to study lionfish. But why does this discovery present such a serious problem for those hoping to find ways to eradicate this glutenous species?

First of all, bigger fish eat more. That means these bigger lionfish could -- and will -- eat more fish at varying depths, including migrating up to the sensitive coral reefs and dining on fish populations there. But there's more (literally) to it.

"In many fish species, a large, mature adult can produce far more offspring that small, younger fish. A large, mature female in some species can produce up to 10 times as many offspring as a fish that’s able to reproduce, but half the size," reports Oregon State University.

That means not only will these fish eat more, but they're likely to have a lot more babies. And there is yet another problem with these many large fish living at greater depths. Part of the eradication efforts include putting lionfish on the menu, to increase how many are caught for food. But in such deep water, the strategy isn't as practical -- which means new strategies for catching the fish must be deployed.

Stephanie Green, the David H. Smith Conservation Research Fellow in the College of Science at Oregon State University, who participated in the dives, says of the discovery, “This was kind of an ‘Ah hah!’ moment. It was immediately clear that this is a new frontier in the lionfish crisis, and that something is going to have to be done about it. Seeing it up-close really brought home the nature of the problem.”

According to OSU, "Aside from the rapid and immediate mortality of marine life [through the voracious appetite of the lionfish], the loss of herbivorous fish will also set the stage for seaweed to potentially overwhelm the coral reefs and disrupt the delicate ecological balance in which they exist. This newest threat follows on the heels of overfishing, sediment deposition, nitrate pollution in some areas, coral bleaching caused by global warming, and increasing ocean acidity caused by carbon emissions. Lionfish may be the final straw that breaks the back of Western Atlantic and Caribbean coral reefs, some researchers believe."

Tags: Conservation | Fish | Oceans