Recent investigation and monitoring of the River Clyde by the newly formed Clyde River Foundation is confirming that salmon and sea trout are now returning to parts of the Clyde catchment, which they have not used for over a century. These investigations build on earlier survey work carried out by Fisheries Research Services (FRS) Freshwater Laboratory prior to the setting up of the Clyde River Foundation, and the Freshwater Laboratory continues its local involvement through the provision of background information and advice.
With talk of declining salmon populations in many of Scotland's rivers, this is encouraging news. Although other rivers in the Central Belt have also been badly affected, the Clyde catchment experienced the worst pollution and now the most spectacular recovery.
The principal cause of the extinction was pollution of the lower rivers and upper estuaries, with the demise of the rivers aggravated by the degradation of spawning and nursery areas through urban, domestic, colliery and other industrial wastes. Weirs obstructed the river systems with inadequate provision for upstream passage of spawning adults.
By the late 18th century the runs of salmon in much of Central Scotland were in decline and the situation in the 19th century became increasingly poor with salmon disappearing from many of the rivers. By the early years of the 20th century, salmon had effectively become extinct in the River Clyde above Dumbarton and many of the other rivers of the Central Lowlands.
Restoring salmon to these polluted rivers has taken the best part of another 100 years but the results are very positive, with salmon now very well established, particularly in the River Nethan.
The Scottish Environment Protection Agency (SEPA) is the regulatory body, which has driven the improvement in water quality. Ross Doughty of SEPA says: "The first steps towards reversing the appalling state of the Clyde were taken in the 1860s and led to the Rivers Pollution Act 1876. Further legislation followed and over the last 30 years, the control of water pollution in Scotland has been strengthened, in particular with the establishment of SEPA and with the advent of new European legislation such as the EC Water Framework Directive. The key factor which allowed salmon to start returning to the Clyde was the improvement in dissolved oxygen concentrations in the Clyde estuary, through the building and subsequent improvement of sewage treatment works."
The salmon began to return to the Clyde sometime around 1978 when they were noted ascending the River Gryfe in significant numbers and since then they have also become re-established naturally on at least six other river systems in the Central Belt of Scotland from which they had become extinct.
"The improvement in water quality in the lower reaches of the rivers over the last 30-40 years is the main reason why salmon have managed to re-colonise many of the rivers from which they had been eliminated by pollution," says Ross Gardiner of FRS. "However, to allow salmon to reach the productive upper reaches of tributaries, the building of fish passes at weirs has also been crucial, and this work continues. Of particular importance to the Clyde was a fish pass constructed at Blantyre Weir in 1994, which allowed salmon much improved access to favourable habitat in the River Clyde between Blantyre and the Falls of Clyde, and in the River Nethan."
In contrast to the alarming stories of decline in other salmon populations, the Clyde stocks are still increasing and now support a significant sport fishery. "The news is good, but," says Ross Gardiner, "there is no room for complacency. There is a continued need to ensure water quality and good quality habitat are being maintained, and to continue to improve the fish passage arrangements for salmon at weirs. The establishment of the Clyde River Foundation, which now employs a full-time fisheries scientist, will also help enormously."
For more information contact:
Dr Willie Yeomans, Clyde River Foundation
Tel: 0141 548 4569
Ross Doughty, SEPA
Tel: 01355 574255
Ross Gardiner, FRS Freshwater Laboratory
Tel: 01796 472060
Email: Ross Gardiner
Link: