Grouper could be solution to invasion of lionfish

(CNS): As the campaign continues to maintain the grouper fishing ban at Cayman’s one and only remaining spawning ground, new research suggests that the fish may well be the solution to the recent invasion of lionfish into Caribbean waters. The study, published this week in the online journal PLoS One, explained that lionfish numbers were ten times lower in reefs with lots of large groupers. The increase in lionfish in Cayman over the last few years has caused significant alarm because, while they may look pretty, they are voracious predators.

The spiny fish are not native to the Caribbean and are believed to have been released from aquariums in the United States and eventually made their way through to the local region. Lionfish numbers have increased dramatically in the last few years and they have now invaded the entire Caribbean. The fish eat significant numbers of small fish and conservationists are concerned about their impact on the local native fish populations.

A research team from the University of Queensland (Australia) and American Museum of Natural History (New York) studied the invasion of lionfish in a remote stretch of coral reef in the Bahamas.

"In 2006 we did not encounter any lionfish but by 2010 they were at all of our 12 study sites,” said the reports lead author, Professor Peter Mumby. “However, the number of lionfish was ten times lower in reefs with lots of large groupers".

The team surveyed reefs inside and outside the Exuma Cays Land and Sea Park, which is one of the best marine reserves in the Caribbean, having been established in 1959.

"With long-term protection from fishing, grouper numbers are among the highest in the Caribbean and we believe that groupers are eating enough lionfish to limit their invasion on these reefs," Prof Mumby added in a release from the Fore projects.

This news is positive for conservation efforts but Prof Mumby adds a cautionary note. "Years of over-fishing means that densities of large grouper, like the Nassau grouper, are low throughout most of the Caribbean. If we want grouper to help us control the lionfish invasion we'll have to develop a taste for lionfish instead of grouper and drastically reduce the fishing of this species".
 
Lionfish have high venomous spines to protect them from predators and there are few known predators of lionfish. However, previous studies have found lionfish in the stomach of Groupers and the native fish is emerging as the best potential natural answer to control the lionfish numbers.

See the full research manuscript here