Clean-up efforts breed optimism as salmon return to Scotland's west coast

After more than a century of industrial pollution and agricultural interference the wild salmon runs of the west coast of Scotland are being brought back to life.

After more than a century of industrial pollution and agricultural interference the wild salmon runs of the west coast of Scotland are being brought back to life.

From the ancient breeding grounds of Wester Ross to the tributaries of the river Clyde, scientists are reporting significant numbers of juvenile and adult salmon in stretches of water where they had previously been wiped out.

The salmon is regarded as an excellent environmental indicator because its unique life-cycle makes it highly sensitive to changes in temperature, habitat and water quality.

On the Clyde in Glasgow at least seven tributaries, including the Rotten Calder, White Cart and Nethan are again supporting baby salmon.

Less than 20 years ago the Clyde, and in particular the estuary through which the salmon were forced to migrate, was so polluted with sewage and industrial waste it was unable to support any fish at all, bringing to an end 800 years of salmon and sea trout fishing.

With the advent of the industrial revolution began the decline of the salmon and trout populations. Domestic waste from burgeoning populations and pollutants led to the extinction of salmon in the lower rivers and upper estuaries.

By the beginning of the 20th century, pollution aggravated by man-made obstacles such as weirs built to power mills and factories, blocked the passage of spawning adults attempting to reach the upper rivers.

But now, for the first time in about 150 years, salmon are being found up-river from the estuary, indicating that efforts to clean the river are working and that once again the fish are able to negotiate what was once one of the world's most industrialised waterways. Willie Yeomans, catchment manager for the River Clyde Foundation, said: "It is incredibly good news that rivers which were once completely devoid of fish are able to support salmon once again.

"In the last 20 years a lot of work has been done to clean up the Clyde... We still have a long way to go to ensure the survival of the salmon runs but the fact that they are coming back and are able to live and breed in the tributaries means we are getting there."

Further north along the west coast efforts to alleviate problems caused by fish farming have helped to reopen the rivers to wild salmon.

For years the proximity of fish-farming cages to the mouths of rivers was blamed for the wild salmon becoming infested with sea lice before they could reach spawning grounds.

Improvements in combating the parasites have reduced the spread of infection from caged to wild salmon and have allowed numbers of juvenile and adult fish in rivers such as the Lochy, the Cona and Scaddle to increase substantially.