Campaigners who say salmon are close to extinction on a river say the species could be re-established if improvements are made to an old weir.
Fish cannot cross the School Weir on the River Sid in east Devon because it is too high to jump over, meaning that the species only exists in very small numbers, said the Westcountry Rivers Trust.
The trust said salmon were “functionally extinct” in the river and urged authorities to help them.
The Environment Agency said it was considering installing a sloping ramp up the river for the fish to migrate upstream to their spawning grounds.
Hannah Parvin, of the Westcountry Rivers Trust, said: “Salmon are functionally extinct from this catchment because of the weir.”
Without the weir, she said the river was a “good and healthy environment for salmon, and other migratory species, to spawn and raise their young”.
“Salmon are declining across the UK, they’re an endangered species in the UK, so if we can do something on this river to help increase their population that’s always going to be a positive,” she said.
Charles Sinclair, of the River Sid Catchment Group, said surveys had discovered young salmon in the Sid, which runs through Sidmouth.
“We’ve seen them jumping but they just can’t get over the weir, and then they’re stuck here,” he said.
“We need to help out and solve some of the problems nature is facing.”
The group has been assisting the migration of salmon by netting them and carrying them over the weir.
Jessica Ring, from the Environment Agency, said: “We are thinking of a sort of nature-like fishway, which would be a sloping ramp up to the weir crest which will allow multiple species of fish to be able to access the upper river potentially with a lowering of the weir as well alongside that.”