Poisonous fish can spread in less than 2 years – 7/1/2023 – Environment

“Who ever put him in an aquarium, for example… Sometimes he eats all the other fish in the aquarium.”

The comment was made by biologist Marcelo Soares, a researcher at Labomar at the Federal University of Ceará (UFC). The unusual scene illustrates the voracity of the lionfish (pterois volitans), an invasive species from the Indo-Pacific that recently arrived on the Brazilian coast and that, in a short time, could spread throughout the entire coast of the country.

In less than two years, says Soares, citing the most recent estimates by scientists, the species could take over the entire Brazilian coast and reach Uruguay, causing damage to fishing and tourism. In the Caribbean, the passage of the animal is associated with an 80% reduction in the population of fish that inhabit coral reefs in some regions.

It has no natural predators in the Atlantic, is a persistent and avid hunter, adapts to different types of environments and females can lay up to two million eggs per year. The “mane” around the body is formed by a series of poisonous spines that are not lethal to humans, but can cause serious injuries.

A history of almost 40 years

The lionfish saga is one of the most successful stories of invasion of marine animal species.

Available scientific evidence points to it beginning in 1985 in Florida. It was the first time that the lionfish, native to the Indo-Pacific, was sighted in the Atlantic Ocean.

It is not known exactly how it ended up there, near the coast of Dania Beach. One hypothesis is that it was released into the sea by an aquarist. There are also reports of the accidental release of lionfish into the region in 1992, when Hurricane Andrew swept through Florida and destroyed a local aquarium.

Since then, the species has been dispersing across the Atlantic Ocean. It took over the southeastern coast of the United States, the Gulf of Mexico, the Caribbean… until it was spotted, in 2020, off the north coast of Brazil.

Advancing from the Caribbean to the Brazilian Sea is no simple task for an invasive species. The mouth of the Amazon River —or the Amazon-Orinoco plume, in technical terminology— is an enormous natural barrier that makes it difficult for animals to move from one side to the other. There are billions of liters of sediment dumped into the ocean every minute – and this material does not immediately dissolve in salt water, it spreads for kilometers out to sea and for meters deep.

It’s not easy to pass. The hypothesis is that the lionfish used reefs that exist in the region of the Amazon plume as a base to cross from one side to the other, says Soares, arriving in Amapá and Pará. Scientists believe this happened around 2017 and 2018.

“These reefs that exist in the Amazon are between 70 and 220 meters deep, it’s very deep. But this animal can survive up to 300 meters deep, so it can use that area. Apart from that, it’s a very resistant animal, it can withstand low salinity. “

Once on the Brazilian coast, the lionfish continued advancing towards the Northeast, in an area where the marine current flows towards the Caribbean, adds the biologist. Swimming against the current, he reached Maranhão, Piauí, Ceará, Rio Grande do Norte.

In Ceará, Soares and his colleagues at Labomar observed the first animals in March 2022. At that time, fish averaged between 14 and 15 centimeters. A year later, in June 2023, the size remained: 30 centimeters.

“Today it is already found in all the municipalities of Ceará, on the coast of Rio Grande do Norte… and it is going down.”

According to the researcher, when the lionfish “turned the corner” of Brazil —the curve on the map of Rio Grande do Norte—, it arrived in a region where the marine current flows to the south. “Which means he goes faster now,” he comments.

At the moment, the species is on the border between Pernambuco and Alagoas, as indicated by the monitoring platform organized by Soares and researcher Tommaso Giarrizzo to monitor the dispersal of the lionfish.

The tool is collaborative: via a computer or a cell phone application, fishermen and divers send images and information about their encounters with the species.

What’s the problem?

But why is the proliferation of an exotic species like the lionfish an environmental problem?

As it competes with other species for resources and feeds on a wide variety of animals —without being threatened by predators— it can threaten biodiversity wherever it passes.

This could impact tourism, for example. “Anyone who dives wants to see life, right?”, illustrates the researcher.

With less fish available, fishing could also be affected.

In Ceará, artisanal fishermen have an old tradition of creating artificial reefs with tires and other sunken objects to attract fish, the so-called marambaias.

“This goes from father to son, the location of the sinking. It’s almost like a property to fish at the bottom of the sea”, explains Soares.

In an expedition made on the coast of Jericoacoara beach, the Labomar team found several lionfish inside these structures.

What can be done to avoid the worst?

The biologist says that it is practically impossible to eradicate the lionfish from the areas where it has already established itself, but population control can help to reduce the negative impacts.

In this sense, he highlights the initiatives implemented in Fernando de Noronha as positive. There, the Chico Mendes Institute for Biodiversity Conservation (ICMBio) formed a partnership with diving operators to capture the species.

As a conservation area, however, the archipelago is a special case. In most cities on the north and northeast coast where the species has spread, there are still no coordinated initiatives by the state and federal governments to actively try to control the increase in the lionfish population.

“The positive point is that we have a network of universities prepared to work with public bodies. We just need to make this partnership, everyone together, which is the only way to combat the problem”, says Soares.

Other countries on the lionfish invasion route have been testing different strategies in recent decades.

Cities on the coast of Florida, for example, began to organize events to hunt the species. In May, the Okaloosa County region celebrated a record number of animals removed during its annual tournament: 25,699.

In some places in the Caribbean, in addition to fishing to control the species, the meat is consumed in restaurants. This is the case of the US Virgin Islands, where Soares was recently as a visiting professor.

“Of course, you have to treat the fish, remove the thorns, which are poisonous, but there it is used for food.”

“They also make use of the leather to produce shoes, wallets, purses… a kind of tanning of lionfish leather. So there are economic and social alternatives that generate income and help to eliminate the animal.”

These alternatives need, however, to be carefully evaluated by local authorities, says the researcher. It is first necessary to understand whether the animals on the Brazilian coast are contaminated and, if you decide to regulate consumption, be concerned about avoiding the risk, for example, of giving economic value to the species and ending up encouraging its cultivation —which would make the problem worse.

In the report, Ibama stated that, since 2014, it has been proactively preventing the importation of these animals for any purpose, even though the legislation until recently allowed the purchase. The ban came last year, with the publication of an ordinance that prohibits the importation of lionfish for ornamental purposes.

Also in 2022, the municipality created a working group with a specific focus on the problem. Among the objectives are the formulation of a proposal for a normative act for the management of the species.

“The normative regulation to be created specifically for the lionfish will bring more specific commands for the use and benefit of this species”, says the text sent to BBC News Brasil.

In this sense, in the second half of this year, Ibama is considering organizing a workshop to discuss alternatives for using the animal’s meat and leather, “if there is a market”, and to build a “comprehensive national plan to combat lionfish”.

At the moment, even though there is no legal prohibition, the municipality does not recommend consumption, as it is a “poisonous species, whose handling requires specific techniques”.

This text was originally published here.