SALMON are staging a spectacular comeback in the Ouse and other rivers across North Yorkshire following major improvements in water quality.

Environment Agency chiefs say large numbers of the fish are now coming into the tidal Ouse and swimming past York up to the Ure, where they spawn on gravel beds.

But salmon have also been going up the River Derwent, with the fish being spotted as far up as the River Rye at Nunnington. Other creatures such as otters have also grown in numbers on the tidal parts of the Ouse.

David Bamford, fisheries technical specialist, said salmon used to be common in rivers such as the Ouse up until the late 1930s, but numbers declined dramatically during and after the war because of pollution.

He said numbers remained low up to the mid-90s, when droughts led to oxygen levels falling too low for them in the Boothferry area.

But he said improvements to the treatment of sewage at Naburn works and reductions in industrial pollution further downstream had then led to them returning by the late 1990s.

“In the past couple of years, we have seen a quantum leap,” he said.

“Salmon were seen last November leaping the weir on the Swale at Topcliffe, and large numbers were seen in the Laver at Ripon last autumn.”

He said a fish counter was being installed on the Ure at Newby Hall which would help detect how many salmon there were. During a survey of fish in the Ouse at Naburn, the agency had caught a salmon weighing up to 10lbs, which had then been returned to the water.

“You can be crossing Ouse Bridge any one time in York and there could be a salmon swimming in the river below, even though you might not be able to see it.”

He said the agency was encouraging fishing for salmon by anglers, who needed a specific licence. Such fishing had economic benefits and anglers also provided the agency with useful information about the fish.