Bottlenose dolphins: scientists at the University of La Rochelle are investigating

Since early December 2023, more than 350 small cetaceans, mostly common dolphins, have been found off the French coast of the Bay of Biscay. one already a new episode of dead winterespecially early, documented by the marine mammal Pelagis observatory.

This research unit of the University of La Rochelle coordinates national stranding network, allows you to count, but also recover bodies to study them. And the judgment of scientists is unappealable: it often isfishing accidents. This is revealed by necropsies (autopsies of animals) carried out in La Rochelle.

‘Healthy’ dead dolphins

Go to the basement of the Pelagis observatory in one of the science faculty buildings in the Minimes district. The autopsy room is full of dead dolphins, some frozen to preserve them. scalpel in hand, veterinarian Sarah Wund is caring for an adult female found in very good condition, a few days ago, at the foot of the sands of Pilate in Girona.

Sarah Wund cleansed the entire digestive system. “We see that the stomach is full of fresh matter, the vet does the analysis. With fish bones. A priori, an eater is a healthy animal. This is accreditation accidental death hypothesisrelated to fishing nets.

Marks on the skin

first step, visual inspection of the carcasshad already revealed the first clues. “On the rostrum, on the beak, we see linear lesions that surround, Portrays Eléonore Méheust, also known as Léo, a marine biologist who helps Sara Wund. This is because the animal is entwined and causes lesions.”

Photographs are taken of each stage of necropsy, dissection of the body. Strict protocol to avoid any disputesSarah Wund, who refuses to pass for mainstream anti-fishing, highlights her veto: “Our job is really to objectify the situation. I really want to know what the animals are dying from, and especially if they are carriers of pathologies.”

is loaded

5-10,000 dolphins were accidentally caught

Diseases that explain several deaths. But For 95% of dolphin strandings this winter, Pelagis’s chosen cause is clear: fishing accidents. Some animals also wear rings placed by the fishermen themselves: “They feed us data and that feeds our research programs, Welcomes Hélène Peltier, research engineer at Pelagis. It is thanks to this information that we can tell you today that eight to ten people die for one dolphin that comes ashore. Many sink after being thrown back into the sea, their bodies never to be found.

Thus, Pelagis estimates the number of common dolphins caught by accident in the Bay of Biscay each winter at between 5 and 10,000. I mean well above the sustainable level for this species. “The calculated threshold between Gibraltar and Norwegian waters, Hélène Peltier says, this equates to 985 incidental captures per year for a common dolphin.” However, French waters alone have five to ten times more deaths.

Downside risk

An alarming sign of the extinction of this species, mothers give birth to young and young. “And what we don’t want is to lead to species decline. Because once it starts, it’s very difficult to go back.” warns the scientist from Pelagis.

Technology has yet to offer a parade. “We know that acoustic repellants work in certain situations, on certain types of gear. Accepts Hélène Peltier. In others, it should be tested, but on a larger scale.” Especially in crosshairs netting at sea It is very common, especially in Charente-Maritime, with tens of meters of boats. pelagic fisheries also causes occasional seizures.

Should winter fishing be closed?

For scientists, the immediate solution is clear: a Winter closing for these two types of fishing. “We’re talking about compensatory closures, Hélène Peltier emphasizes. The idea is also to find solutions that allow these fisheries to reopen, changing practices and limiting catches. »

A call by NGOs, as Sea Shepherd reiterated this week. 2023, “one year more” denounces the association in a press release, which in turn challenges the state. Sea Shepherd launched a surveillance operation for fishing boats only, and from the first night two dolphins caught by accident spotted by militants, netted about twenty nautical miles from Ile de Ré.