MPs are calling for a ban on some types of fishing unless trawler crews reduce the number of dolphins and porpoises being killed in nets.
Pair trawler crews deny they are responsible for the deaths
A new report from the Commons environment committee, chaired by Cornish MP Candy Atherton, is calling for pair trawling for sea bass to stop in two seasons, unless cetacean deaths are cut.
A report last week by conservationists concluded some dolphins could be wiped out if the fishing continues in the same way and one Devon campaigner says waiting any longer for a ban will result in thousands more casualties.
Pair trawler crews have always denied they are responsible for the deaths.
"We actually now need action," said Ms Atherton
"Words not good enough. And even the fishing industry themselves were saying to us we need can't sustain this, it's very bad for the fishing industry and action needs to be taken."
But Linda Hingley, who set up Brixham Seawatch to record dolphin deaths, said it was too long to wait.
She estimates 10,000 Common Dolphins will die on UK beaches in the next two years.
The MPs also make recommendations about the use of "pingers" - small battery operated devices that can be attached to fishing nets and deter dolphins from coming too close to the nets.
The Government says it will consider the Committee's recommendations carefully.