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The fishermen's union warns of the presence of carnivorous fish in several lagoons, particularly in the East and around Mahébourg. According to its spokesperson, they represent a threat to the marine ecosystem. The Ministry of Blue Economy and Fisheries explains that a team of scientists will be dispatched to the site soon.

The Fishermen's Union warns against the presence of carnivorous fish, in particular the red bream and the sea bass, in the eastern lagoons in particular. These species, according to Judex Rampaul, the union's spokesperson, pose a serious threat to the marine ecosystem. Their carnivorous diet and their ability to adapt to new environments can cause a decline in local fish and shellfish populations, leading to a loss of biodiversity (see box).

Why this sudden appearance of carnivorous fish in the lagoons? “An aquaculture project launched more than two decades ago is the cause,” says Judex Rampaul. He takes a leap into the past and mentions the 2000s, when an operator obtained a concession to carry out aquaculture in Pointe-aux-Feuilles in the East.

“During the meetings, we learned that 2,000 red bream and sea bass had been imported and put in ponds in order to acclimatize them to our waters before introducing them into our sea,” recalls the union spokesperson. He explains that the company that had introduced them went bankrupt in 2003-04 and that another firm took over all the infrastructure. He specifies that the Ministry of Blue Economy and Fisheries continues to authorize aquaculture.

Judex Rampaul continues that at the time, they had reported that these fish are not adapted to our waters. He points out that many demonstrations had even been organized. “The promoter claimed that there would be no impact on the environment, but we insisted with the Ministry of Fisheries saying that there would be problems,” he points out.

He adds that in 2024, after more than 10 years of the Fishermen's Union's fight, red bream and sea bass have entered the lagoons. “We have done research and we have found that red bream and sea bass are starting to enter the lagoon. Scientific reports show that these fish are not suitable for our environment, but our warnings have not been heeded,” he insists.

“Over the last 10 years, we have noticed that in the South-East region, many species are starting to disappear: cobbler, red mullet, Breton, sardine, small crabs, shellfish and shrimp. These carnivorous fish eat small fish as soon as they are born, thus reducing their population,” explains Judex Rampaul. He is categorical: these carnivorous fish eat small fish of other species, endangering the already declining biodiversity.

He raises another issue: according to him, natural predators, such as dolphins, sharks and “tazars”, invade the lagoon in search of food. “A fish cage has about 50,000 redfish and sea bass. This attracts sharks looking for food. The latter tear the nets and cause damage. Divers are hired to repair the nets, but when the fish house breaks, these fish fall into the lagoon,” he explains.

For him, the authorities concerned are not doing their job. “The government has not taken the problems into consideration. The fish are spreading. If they reproduce in our marine environment, it will be the end. They devour the small species and people are afraid to dive because of the sharks looking for easy food,” he said.

Judex Rampaul looks back on the dramatic episode of the sinking of the MV Wakashio, following which many porpoises and dolphins died. “We still don't have a report,” he says indignantly. He points out that the dolphins do not live in the lagoon. “They were attracted by the concentration of fish. We are alerting the Ministry of Fisheries. We insist that they take measures to destroy the predatory fish that threaten the ecosystem. We must protect our sea.”

The spokesperson for the fishermen's union indicates that these carnivorous species have been seen not only in Bambous-Virieux, but also in Mahébourg and Quatre-Sœurs, that is to say regions where fish farms have been set up.

At the level of the Ministry of Fisheries, it is reassured that a team of scientists will soon be dispatched to the Bambous and Mahébourg lagoon for verifications. “They will conduct a study on the extent of the presence of ombrines in the region. A decision will then be made,” the ministry's communication unit specifies.

Nadeem Nazurally: “Not a threat to the ecosystem”

Nadeem Nazurally, an expert in Marine Aquaculture and Ocean Sciences, says that sea bass production has been halted in Mauritius for several years now, which he says makes the sources of these fish in the lagoons uncertain.

As for the red rump, he argues that it is scientifically established that it cannot reproduce in Mauritian waters. “The conditions necessary for their reproduction, such as water temperatures of 29°C to 30°C and high light intensity, are not present all year round in Mauritius,” he maintains.

He explains that shark studies have also shown that their population is declining and that they are not attacking fishing nets as one might expect. “Real-time research and night observations have not revealed any shark attacks on nets. Local fishermen often catch the escapees (scapies) which do not pose a significant threat to the marine ecosystem due to their inability to reproduce in these conditions,” insists Nadeem Nazurally.

According to him, although these predatory fish are present, they do not represent a major threat to the marine ecosystem. “Concerns about their ecological impact are unfounded and the risk is considered to be very minimal,” he concludes.

Good to know

The drumfish, scientifically known as Umbrina canariensis, is a carnivorous fish. It is also known as the Canarian drumfish. It is found mainly in the eastern Atlantic Ocean and the western Mediterranean. It inhabits sandy and muddy seabeds, feeding mainly on small crustaceans and benthic invertebrates. The drumfish typically reaches 40 to 63 cm in length, with a maximum size of 80 cm.

As for the sea bass, scientifically called “Sciaenops ocellatus” or nicknamed “red drum”, it is a subtropical species present in the western Atlantic, from Massachusetts to northern Mexico. It is especially abundant in surf zones and estuaries, where it feeds on crustaceans, mollusks and fish. Sea bass can reach a maximum length of 155 cm and a weight of 45 kg.

Both species are often raised in aquaculture because of their commercial value. However, their introduction into new environments can pose ecological risks, as their carnivorous diet and ability to adapt to diverse habitats can disrupt local ecosystems, particularly by reducing local fish and shellfish populations.

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