Non-indigenous lionfish have become increasingly common in parts of the Mediterranean in recent years, threatening local ecosystems and posing a danger to humans through their poisonous spines.
Marine biologist Professor Jason Hall-Spencer first saw a lionfish off the coast of Cyprus in 2016. It was just one individual, but the species, which produces around 2 million eggs each year and is devoid of predators. natural in their new environment, it has quickly become prevalent. . “In some places, I’ve seen 40 in one dive,” said Hall-Spencer of the University of Plymouth.
To address the growing numbers of lionfish, Hall-Spencer and other researchers from the University of Plymouth and the Marine and Environmental Research Laboratory in Cyprus have worked with specially trained divers and citizen scientists to coordinate removal events and surveys for six months. The collaboration is part of the European-funded ReLionMed project.
“[Lionfish] they are right in shallow depths where you can swim, we see them at 1 or 2 meters deep, and they can give you a really nasty sting because their fins are full of venom, ”said Hall-Spencer.
While there are records of lionfish in shallow water, they primarily stick to deeper water and therefore pose a greater public health risk to divers, said Periklis Kleitou, lead author of the study published in Aquatic Conservation. “As they expand [their range]We hope that they do not invade the coastal areas, where there are many tourists ”.
But the lionfish is causing more trouble than the threat of a painful sting. Invasions of the species in other parts of the world have shown that carnivorous fish can rapidly colonize reefs and reduce biodiversity in the area, a problem for the ecology of the reef and local fishermen.
Originally from the warm tropical waters of the Indo-Pacific, the first official sighting in Europe was in 2012 and off Cyprus in 2014. Warming oceans and the expansion of the Suez Canal have influenced the invasion of the Red Sea lionfish. . in the eastern Mediterranean. They are spreading rapidly and some have reached Tunisia and Italy.
Now, research shows that removing the fish has the potential to help control their populations.
Hall-Spencer said lionfish were being sighted within marine protected areas (MPAs), established to safeguard native organisms in the Mediterranean. “What [MPAs] what they are effectively doing is protecting these invasive species, they provide shelters, and that is a concern, “he said.
“Eradication is out of the question,” said Dr. Louis Hadjioannou, a research biologist affiliated with the Cyprus Marine and Maritime Institute and the Enalia Physis research center. “We are talking about controlling populations,” he said.
The team conducted five extractions with specially trained volunteer divers who caught between 35 and 119 lionfish per day at each of the three protected marine sites studied off the coast of Cyprus.
The research also used citizen science to monitor the number of lionfish at the survey sites after removals. A combination of citizen science reports and fixed transect monitoring revealed that lionfish abundance declined after removals.
Lionfish recolonization occurred at different rates, which the researchers attributed to connectivity with neighboring reefs. One problem is that lionfish can be found up to 100 meters below the surface, a depth that far exceeds the limits of recreational diving.
“That means there is a reserve of lionfish in unreachable areas,” Hadjioannou said. Those fish can go up to the area that has just been removed and restock.
The monitoring of the lionfish in the study was carried out for a short period of time. Longer-term studies are needed to determine if extractions can be a long-term solution, allow for better timing of events, and help identify which locations to target for the best results.
The researchers identify the need for a multi-faceted approach, including promoting greater protection of large predatory fish that can feed on lionfish and encouraging local fishermen to catch them.
In fact, visitors to Cyprus will soon be able to see lionfish on the menu. It is already seen in the fish markets and in some restaurants. As the market grows, its value is expected to increase. The project is also cooperating with markets to promote the sale of jewelry made from lionfish fins.
“With climate change, lionfish are expected to invade parts of the western Mediterranean,” said Kleitou, and since fish are already abundant in other parts of the south-eastern Mediterranean, “the long-term goal is to continue to transfer our knowledge to their countries. neighbours “.
We must also work to prevent further invasions, Hall-Spencer explained. He described Suez as a “severed artery” that is “bleeding all these fish and other species, including viruses and bacteria, in the Mediterranean.”
“What really needs to happen is some kind of biosecurity control,” he added, and suggested using desalination plants that produce very salty wastewater and placing them in the Suez Canal. “I think it is going to require international coordination and probably international funding to achieve this biosecurity,” he said.