Lessons from Atlantic lionfish invasion shared with Mediterranean

Scientists who have studied efforts to combat the lionfish invasion in the Western Atlantic, including in Cayman, are sharing their findings with people batting an influx of the fish to the Mediterranean.

Lionfish, which are native to the Indian and Pacific Oceans, began invading the Atlantic in the early 2000s and are now found along the eastern coast of the United States, all the way south throughout the Caribbean, including on Cayman’s reefs.

“While the establishment of lionfish in the Western Atlantic is perhaps the most well-studied marine fish invasion to date, the rapidly expanding invasion in the Mediterranean is more recent and has received less attention,” according to authors of a report, compiled by 25 researchers from five continents, which was published earlier this year.

In the report, published in Frontiers in Marine Science website, they reviewed the successes and failures from two decades of lionfish management in the Western Atlantic to give policy recommendations for their management in the Mediterranean.

They noted that two common early approaches attempted multiple times in the Western Atlantic had failed – feeding lionfish to native fish to promote predation, and implementing bounty programs to incentivise the killing of lionfish.

Instead, they recommend these three strategies:

  1. Scuba divers conducting routine removals by spearfishing, which can effectively suppress local abundances of lionfish;
  2. Encouraging the development of recreational and commercial lionfish fisheries, which can promote long-term, sustainable lionfish population control; and
  3. Engaging local communities, for example, with lionfish culling tournaments “which can concurrently achieve multiple objectives of promoting lionfish removals, market-development, research, and public education”.
Source: Lessons From the Western Atlantic Lionfish Invasion to Inform Management in the Mediterranean

They noted that, in some jurisdictions, conservation policies had to be amended to enable lionfish removals in areas where spearfishing with scuba was otherwise prohibited.

“The risk of abusing these policies was mitigated through the use of gear restrictions, diver trainings, and through participatory approaches that integrated scuba divers and stakeholder organizations in lionfish research and management,” the scientists noted.

For example, here in Cayman, lionfish are the only species that scuba divers can legally remove from the local waters. Only approved three-pronged spears can be used and anyone using them must have a license from the Department of Environment. In addition to Cayman, divers have been licensed to spear lionfish in Bermuda, Turks and Caicos Islands, Saba, St. Eustatius, St. Lucia, Aruba, Bonaire, Cyprus, Israel and the Egyptian Mediterranean.

Divers in many Caribbean jurisdictions, including in the Cayman Islands, can be licensed to cull lionfish. – Photo: Norma Connolly

The invasion in the Atlantic, which was first detected in 1985, is thought to have been introduced via aquarium releases in southeast Florida. The lionfish range expansion began in the early 2000s and populations are now established throughout the Gulf of Mexico, Caribbean Sea, and southeastern seaboard of the United States of America. The invasive fish were first spotted in Cayman in 2008.

The first recorded lionfish in the Eastern Mediterranean Sea was in 1991, but their initial establishment in the region in 2012 was in Lebanese waters, the researchers noted in their report. Their introduction into the Eastern Mediterranean was via the Suez Canal.

Over the last decade, the range of lionfish has expanded to the Central Mediterranean and is progressing towards the Western Mediterranean region.

Unsuccessful approaches

Since the start of the invasion, several approaches have been taken to try to tackle the problem. Some have been more successful than others.

Teaching native fish to prey on lionfish: The researchers noted that, in the early phases of the lionfish invasion in the Atlantic, well-intentioned divers attempted to train other fish to prey on lionfish by feeding them speared fish. For example, they said, there are accounts of resident Nassau groupers that learned to lead divers to lionfish, stopping and turning when they reached one.

“Although there were instances of many native fish willingly ingesting speared lionfish, there is little evidence that native fish have become independent predators on lionfish as a result of this training,” the report noted.

This feeding approach also led to dangerous interactions with marine predators, when Caribbean reef sharks, bull sharks and moray eels began associating divers with food.

“These predators will follow divers closely and even attempt to take them (lionfish) from containment devices,” the researchers stated.

They added, “The degree to which this problem occurs varies from place to place, but presenting lionfish to native fish in an attempt to promote predator control has made lionfish removal efforts more dangerous and difficult. We advise that all culled lionfish be contained and removed. ”

Experts advise that lionfish should be placed within a container and brought to the surface rather than fed to other marine animals during the dive. – Photo: Drew McArthur

Bounty programs: The researchers also found that bounty programs to incentivise lionfish removal by paying individuals for each lionfish collected did not work.

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