Dead dolphins are washing up on France’s Atlantic coast in extremely high numbers. The local populations of the mammals are at risk, marine biologists say. Most of them drowned in the nets of fishing boats.
Post mortems often show fractures, broken tails and flippers and deep incisions cut into the skin by the nets. Some have been mutilated as fishermen release their bodies.
“We’re reaching mortality rates that threaten the survival of the dolphin population in the Bay of Gascony,” said Morgane Perri, a marine biologist in Brittany, western France. “For the last three years, we’ve seen more than 1,000 deaths (dolphins and porpoises) in four months each winter.”
Real number of dolphins dying is much higher
Scientists believe the dolphins found on beaches represent a small fraction of the total number dying in fishing nets off the coast of France. The real number is likely to be five to 10 times higher, they estimate.
For decades, dolphins have been caught in fishing nets in the Atlantic waters off western Europe. But marine scientists say the spike in numbers in recent years is a result of shifting fishing practices. In particular, the fishing vessels that trawl in pairs for sea bass.
Activist group Sea Shepherd wants trawlers to be banned from fishing in sea bass spawning grounds and better monitoring of fisheries. Acoustic ‘pingers’ designed to repel dolphins are also being trialed on some fishing boats.
The slow reproduction rates of dolphins, which are mammals and need to surface to breathe, means they are particularly vulnerable to sharp falls in numbers, according to the Pelagis Observatory in La Rochelle. “Once you see the decline, it’s too late,” said Helene Peltier, a researcher at the observatory. “There is no single miracle solution.”