Dead dolphins are washing up on France's Atlantic coast in record numbers.
And marine biologists say it's putting the continued existence of local populations at risk.
Post mortem examinations often show fractures, broken tails and flippers, and deep incisions cut into the mammals' skin by fishing nets.
Observatory researcher, Willy Dabin:
"It's a human activity, exploitation of the marine environment, that's driven by them, it's not natural."
Some marine scientists believe those found on beaches represent a small fraction of those dying in fishing nets off the French coast.
The real number is likely to be five to 10 times higher, they say.
This is not a new problem but a shift in fishing practices may be making it worse - most notably, fishing vessels trawling in pairs for sea bass.
Dolphin populations are particularly vulnerable to sharp falls in numbers as the mammals have slow reproduction rates.
The French National Committee of Maritime Fishermen did not immediately respond to a request for comment.