“Since March 2022, lionfish have been able to move along 700 kilometers of coast,” said marine ecologist Marcelo Soares, who led the latest study. He also mentioned that there are now more than three hundred fish. “We expect the lionfish to also advance along another 6,000 kilometers of the Brazilian coast within two years if action is not taken quickly.”
For many scientists, the question was not whether the species would move south, but when.
“We knew it would spread very quickly once the Amazon barrier was broken,” said Osmar Louise, an aquatic ecologist from Australia’s Charles Darwin University, who was not involved in the study.
The most harmful invasive fish
Native to the Indian Ocean and the southwestern Pacific, the lionfish is highly destructive; It has a devastating effect on the local ecosystems in which they appeared. They eat local fish and disrupt food chains. It has earned it a reputation as one of the most harmful invasive fish species. Coral demons have not only spread to Brazil; The population also settled in the Mediterranean through the Indian Ocean and the Suez Canal. Luiz says he wouldn’t be surprised if they made it to West Africa soon, “bugging” on ocean currents off the Brazilian coast.
One reason for its harm is that it lays thousands of eggs every two to four days. They have poisonous spines on their backs and are able to adapt well to different environments and types of food. Millions of animal larvae are scattered over vast distances through currents, sometimes through hurricanes. But the main problem is that they have few natural enemies in the areas they invade, and the dangers they pose are often underestimated.
“They have a lot of traits that make them successful as a species,” said marine ecologist Nicola Smith of the University of British Columbia in Canada, who was not involved in the latest study. “It doesn’t surprise me that they landed along the Atlantic coast and now end up in Brazil.”
“Coral devils are thirsty predators,” Soares says. Invading fish can pose a threat to endangered species. When there are few animals left of a particular type of prey, other hunters often switch to other species with more specimens. This does not apply to the lionfish. They remain tireless until they also consume the last animals of their kind.
This characteristic makes the lionfish more dangerous to endemic species that live in only one area. Brazil has many of these endemic species.
Coral devils in Brazil
Soares and his colleagues used data from researchers, fishermen and social media posts to investigate the increase of lionfish along the Brazilian coast. Of the 72 animals found during the three-month study, more than half were near man-made structures such as artificial reefs, which locals use for fishing.
“This may not bode well for fisheries,” Soares said. The locals practice a lot of fishing along the Brazilian coast. This is important for the food supply in this region with great social disparity.
Populations of snapper and grouper, two types of economically important fish, can be significantly reduced. In the Bahamas, for example, the lionfish left so little grouper that a ban was imposed on fishing for this fish. (Meanwhile, grouper numbers are finally beginning to recover.)
The study found that the lionfish was in murky waters with a lot of sediment. This makes the common method of containing invasive species, harpoon hunting (where fishermen shoot arrows underwater with which they abuse fish), more difficult.
A recent study found that at least 29 species of endemic fish found off the coast of Brazil are at risk of becoming prey to lionfish. One example is Haemulon squamipinna, a white fish with yellow stripes important to local fisheries. Hundreds of kilometers from the coast, around rocky islands such as the islands of the Fernando de Noronha archipelago, many species live that have only a very small habitat. According to Louise, some species cover only a few square metres.
“We don’t know everything about marine biodiversity yet, especially when it comes to rare and hard-to-find species,” Soares says. If lionfish populations are as large as in the Caribbean, this may be to the detriment of this species.
With lionfish congregating along the coast of Brazil, it will continue to spread irreversibly.
“Once the lionfish has established itself, you can continue to fish as much as you want,” Smith said. “You’re going to lose it, because they keep breeding and replacing the animals that were killed.”
Lion fish taming challenge
For other fish species, removing samples of that species from an area would reduce population density. This does not apply to the lionfish, Smith says.
“Once you get rid of the fish, new fish take their place,” Smith said. “The more you kill, the more you come out of the depths to replenish the species.” This is possible because lionfish often move to places with few congeners.
One way people try to keep lionfish populations in check is through fishing competitions. In this way, many copies can be quickly removed from a large space. Another method is to use special lionfish traps, although about half of the fish caught escape them, according to Smith. In addition, chefs do their best to make lionfish popular as a dish.
But it is not easy to turn an invasive fish with poisonous spines into a local delicacy. People often think that it is dangerous to eat lionfish. In addition, due to the gravity of the spines, it takes longer to catch them with a spear, and their slices, although tasty, are rather small.
But according to Smith, they definitely deserve it.
I’ve eaten a lot there already. It’s delicious, it tastes a bit like a grouper,” he says.
While it probably doesn’t make sense to try to eliminate them completely, containing their populations can limit damage to native fish species. According to Luiz, it is important to monitor the further movement of the lionfish to prevent it from forming new aggregations. In particular, offshore sites, such as remote archipelagos that are not often visited by fishermen or tourists, should also be kept watch.
It is a matter of life or death for native species in Brazil.
“In terms of management, we’ve made the most if we can prevent native species from going extinct in their own hands,” said Louise.