It may take a legion（军团，众多） of scuba（水肺） divers armed with nets and spears, but a new study confirms for the first time that controlling lionfish populations in the western Atlantic Ocean can pave the way for a recovery of native fish. Even if it's one speared fish at a time, it finally appears that there's a way to fight back.

Scientists at Oregon State University, Simon Fraser University and other institutions have shown in both computer models and 18 months of field tests on reefs that reducing lionfish numbers by specified amounts -- at the sites they studied, between 75-95 percent -- will allow a rapid recovery of native fish biomass in the treatment area, and to some extent may aid larger ecosystem recovery as well.

It's some of the first good news in a struggle that has at times appeared almost hopeless, as this voracious（贪吃的）, invasive species has wiped out 95 percent of native fish in some Atlantic locations.

"This is excellent news," said Stephanie Green, a marine ecologist in the College of Science at Oregon State University, and lead author on the report just published in Ecological Applications. "It shows that by creating safe havens, small pockets of reef where lionfish numbers are kept low, we can help native species recover.

"And we don't have to catch every lionfish to do it."

That's good, researchers say, because the rapid spread of lionfish in the Atlantic makes eradication virtually impossible. They've also been found thriving in deep water locations which are difficult to access.

The latest research used ecological modeling to determine what percentage of lionfish would have to be removed at a given location to allow for native fish recovery. At 24 coral reefs near Eleuthera Island in the Bahamas, researchers then removed the necessary amount of lionfish to reach this threshold, and monitored recovery of the ecosystem.

On reefs where lionfish were kept below threshold densities, native prey fish increased by 50-70 percent. It's one of the first studies of its type to demonstrate that reduction of an invasive species below an environmentally damaging threshold, rather than outright eradication, can have comparable benefits.

Some of the fish that recovered, such as Nassau grouper and yellowtail snapper, are critically important to local economies. And larger adults can then spread throughout the reef system -- although the amount of system recovery that would take place outside of treated areas is a subject that needs additional research, they said.