Invasive Species: Lionfish are Spreading, and We Need to Kill More of Them

Lionfish are a major issue for Caribbean reefs. This invasive species gobbles down native fish, destroying local ecosystems. Now, a new study reveals that culling strategies are too small and that more efforts need to be made in order to eradicate this species from the area.

"For every lionfish we remove during local derbies or spearfishing, there are probably hundreds of others we miss," said Matthew Johnston, one of the researchers, in a news release. "What is really needed to lower their numbers is consistent removal of the fish in all the places they live-deep, shallow-remote-and of all ages. Derbies and spearfishing only target adult fish in shallow water. Unfortunately, that's simply not enough, and to be effective we also have to consider the impact of currents that spread the lionfish larvae."

The researchers have been studying lionfish for some time. They used computer models to combine ocean currents and biological traits of lionfish in order to predict their spread. This revealed that lionfish are spreading rapidly since all of our waters are connected by ocean currents.

"We're all connected by water flow," said Johnston. "That means one area that has uncontrolled lionfish populations can dramatically increase lionfish numbers in nations downstream."

The scientists found that the amount of culling that would be needed to be effective at reducing lionfish numbers would be a regular remove of 20 percent of the population per month in an area that had a lot of lionfish. It would also require culling in regions upstream to "choke off" the supply of larvae carried by currents.

"The culling we're doing with local derbies is helping, but it's really a drop in the proverbial bucket," said Johnston. "If we're to have a significant impact on the lionfish population, we need to be more strategic in our removal efforts and find more ways of removing them from all of our waters, and do it consistently."

The findings are published in the journal Marine Ecology Ecology Progress Series.

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