Invasive Lionfish are More Like Terminators Than Predators: Hunting Behaviors Wipe Out Species

Invasive lionfish are quickly spreading across the Caribbean and the Atlantic, hunting prey and disrupting ecosystems. Now, scientists have taken a closer look at the behavior of this species and have found that it's not just a predator, but more like the "terminator" in the popular movie.

Most native predatory fish are attracted to prey when their numbers are high. This leads to successful attacks and requires a minimum amount of energy to catch and eat other fish. Yet it turns out that lionfish have unique characteristics that make it possible for the fish to simply not stop until the last of their prey is dead-like the terminator.

"Lionfish seem to be the ultimate invader," said Kurt Ingeman, one of the researchers, in a news release. "Almost every new thing we learn about them is some characteristic that makes them a more formidable predator. And it's now clear they will hunt successfully even when only a few fish are present. This behavior is unusual and alarming."

In order to better understand the predatory behavior of lionfish, the researchers compared predation rates between reefs with the invasive lionfish and reefs with native predators alone. The scientists found that when prey fish were present at low population density, the rate of mortality with lionfish present was four times higher than that caused by native predators alone, such as medium-sized groups or trumpet fish. In fact, it appeared that lionfish stayed in the same area rather than moving on like native fish when prey fish populations became scarce.

The findings reveal that lionfish are efficient hunters and, more importantly, have the potential to wreak havoc on ecosystems. That said, not everything is hopeless when it comes to these invasive species.

"There's a strong pressure here for natural selection to come into play eventually," said Ingeman. "We know that fish can learn and change their behavior, sometimes over just a few generations. But we don't have any studies yet to demonstrate this is taking place with native fish populations in the Atlantic."