Salmon (Hansard, 22 May 2003)

§ Mr. Morley

One cause of the decline in salmon stocks may be increases in river temperatures resulting from natural factors or human activities. This could reduce the survival or reproductive success of the fish. The tags used in the study record temperature and transmit the fish's position, allowing scientists to investigate whether or not adult salmon show temperature preferences during upstream migration. This is of particular relevance to the spring-running multi-sea winter salmon in the Avon, which are resident in freshwater for many months prior to spawning. The results of this work will be used to provide advice to Government and other organisations dedicated to the conservation and sustainable management of salmon stocks, on the potential impacts of habitat management practices and climate change on salmonid populations.

Between 1985 and 1990 more than 400 salmon were tagged with radio transmitting tags in the Avon estuary. The great majority of these fish entered the Avon and were tracked migrating upstream to their spawning areas. 45 were reported caught by anglers, which is consistent with recapture rates elsewhere of conventionally tagged fish. No radio-tagged fish were found dead in the river. This suggests that tagging salmon with radio tags has a negligible influence upon their natural behaviour or survival.

Both riparian owners and angling interests were consulted through the Environment Agency, who discussed the work with the Chairman of the Avon and Stour Fishery Association; riparian interests were sent a copy of a letter from CEFAS explaining the purpose of the work and the methods to be used. The Chairman of the Wessex Salmon and Rivers Trust, and English Nature, were also consulted.