Chapter 16. The Return of Salmon to Cleaner Rivers - England and Wales

Summary

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• Industrial and urban development during the 19th and early 20th centuries brought about the extinction of salmon from many rivers. Over the last 40 years, increasingly strong regulation of discharges from industry and sewerage systems, combined with reductions in heavy industry and large-scale investment in water treatment, have resulted in major improvements in water quality. As a consequence, salmon are returning to an increasing number of rivers including the Thames, the Taff, the Tyne and, most recently, the Mersey. In some rivers, stocks have recovered sufficiently to provide fisheries. The Tyne now boasts the highest rod catch for salmon of any river in England or Wales at 2513 in 2001. This reflects not only the improved catch in the Tyne but also the decline of some other rivers; 42% of rivers have exhibited a statistically significant decline in rod catch over the period 1974-98, compared to 17% showing an increase. Recovering rivers now contribute about 25% of the annual rod catch of salmon, due largely to improvements in water quality aided by constraints on exploitation and, on some rivers, to stocking and to the removal of obstructions to migration. The impact on water quality of point discharges in urban areas has been, and continues to be, progressively reduced, but pollution in rural areas, particularly from diffuse sources, is an increasing concern. Despite major reductions in sulphur emissions and changes in forestry practices, acidification remains an issue in some upland areas, though mitigation by liming has proved locally successful in restoring salmon stocks where circumstances permit. The severity of some types of pollution associated with the intensification of agriculture has been reduced, notably from slurry and silage, but other aspects particularly from silt and pesticides, and compounded by flow regime changes, remain a challenge.