In a large room open to the outside of the University of La Rochelle, Willy Dabin and his colleagues are busy around the animal, found on the beach of Saint-Hilaire-de-Riez in Vendée in February. The cetacean was kept in the cold, its body was a little degraded by the birds, but at first glance, the study engineer, in charge of the stranding part at Pelagis, a scientific institute which has been monitoring strandings since the 1970s, spots the marks on his skin.

Parallel bands on the belly, “a very rectilinear mesh”. “Compressions while the animal was alive,” he says.

Throughout the autopsy, the findings will remain neutral. It is not he who interprets the signs. Everything is recorded in writing, photographed, so that veterinarians can establish a diagnosis. But the external lesions immediately give rise to a hypothesis: caught in fishing nets. In this case, the dolphin remains stuck underwater, and dies of asphyxiation.

Same findings on the long beak (rostrum) of the marine mammal: we can see encirclements on the upper and lower lips in continuity, teeth have moved in alignment with these lines, some are even broken.

On internal examination, under the thick skin of the dolphin, the flesh has changed color under these compressed bands: it has taken on a purplish complexion, when it should be white.

Several sets of clues make it possible to establish a diagnosis of traumatic death: an animal in good health, with specific external lesions, death by asphyxiation, a full stomach (the dolphin approaches the nets to feed), the absence of major co-morbidity, or congestion of several organs, lists Sarah Wund.

Veterinarian, she makes her own report in parallel, for a double list of checks during the autopsy. Depending on the findings, a degree of certainty is associated with the diagnosis.

“Dolphins pursue the same prey as the species of fish targeted by fishermen”, explains Elodie Martinie-Cousty, pilot of the Oceans, seas and coasts network of the NGO France Nature Environnement (FNE), which assists in the operation.

“In France, we lost two years with a new minister (of the sea, Annick Girardin) and a government which did not want to hear the scientists, and asked for additional studies”, she laments. “Meanwhile we are not reducing catches”.

In 2016-2017, a first spike in strandings on the Atlantic coast sounded the alarm. Since then, their number suggests catch levels “which are not sustainable” for populations of common dolphins, a protected species, in the Bay of Biscay, Pelagis tirelessly reminds us. A network of more than 400 correspondents helps it monitor the coast.

In this area, the annual catches are estimated “between 3,000 and 11,000” dolphins, for a European-wide population of 680,000 individuals, underlined Ifremer in early April on the occasion of the launch of the Delmoges project, aimed at better understanding the increase in accidental catches by fishing vessels since 2016 and to propose different ways to reduce them.

Autopsy techniques, increasingly advanced, should make it possible to refine knowledge of the causes of death. Incidental captures, mainly by pelagic trawls and gillnets, are the main cause of death among stranded dolphins.

France is in the sights of the European Commission, which accuses it of not taking sufficient measures to reduce accidental catches “in its waters and by its fleet”. If she does nothing, she risks financial penalties.

The measures taken in response to this warning — installation of underwater pulse transmitters (pingers) on trawlers and improvement of surveillance (on-board cameras, observers on board, aerial observation) or obligation to record incidental catches – – are being assessed, according to a Commission source.

“We have a possibility of closure (temporary fisheries, editor’s note), we don’t do it, it’s the dolphins who pay the price”, storms MEP Caroline Roose (Greens), who attended that day at the autopsy, as did Senator Arnaud Bazin (Les Républicains). And to recall that the European fund dedicated to maritime affairs (FEAMPA), could be used to finance other fishing techniques or compensation in the event of closures.


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