Efforts in the Caribbean to eliminate the invasive lionfish are barely making a dent in reducing overall numbers and containing their spread, according to a new report.
This is because the culling effort is too small and locations for culling are chosen without taking into consideration direction of currents which can carry lionfish larvae to downstream regions far away, said the new analysis published in the journal Marine Ecology Progress Series.
Costa Rica is engaged in an official battle against the fish, and fishermen on the Caribbean coast conduct contests to kill the brightly colored creatures.
“For every lionfish we remove during local derbies or spearfishing, there are probably hundreds of others we miss,” said Matthew Johnston, of Nova Southeastern University’s Halmos College of Natural Sciences and Oceanography. “What is really needed to lower their numbers is consistent removal of the fish in all 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.”
He was quoted by the university.
In this new study, Johnston and fellow researcher Sam Purkis estimated the amount of culling that would be needed to be effective at reducing lionfish numbers, the university said in a report on the academic article. They found that control efforts would require regular removal of at least 20 percent of the population per month in an area that had a lot of lionfish, but would also require the same level of culling in regions upstream to choke off the supply of larvae carried by currents, the university said. Furthermore, this culling would need to target all lionfish, large and small animals and those living in deep and remote waters, it added.
An important part of the solution should be international cooperation between the affected nations in the entire Caribbean, the United States, Mexico, and Central and South America, the university quoted him as saying.
He said coming together to address the issue is urgently needed as it would benefit every nation plagued with lionfish, he added.
Lionfish have no natural predators, and they use their large fins to herd smaller fish into a space where they can be consumed easily.
The fish showed up in Costa Rica in 2009.
Researchers at the University of North Carolina at Chapel Hill estimated in 2013 that approximately 27 percent of mature lionfish will have to be removed monthly for one year to reduce its population growth rate to zero.
The lionfish has been munching its way through all sorts of sea creatures in the Caribbean for at least 10 years. The threat to juvenile fish is so great that the Asociacion de Pescadores Artesanales del Caribe Sur runs an annual contest.
The group includes fishermen from Puerto Viejo to Manzanillo and Punta Uva who are seeking to preserve their traditional lifestyle by snagging as many lionfish as possible.
The best method is spearing, and the fish is reported to be tasty as long as cooks avoid the poisonous spines.