The Watersmeet and Glenthorne fishery on Exmoor's River Lyn is to remain closed until the end of the 2013 season to safeguard salmon and sea trout stocks.
The Environment Agency closed the fishery on July 12 following a higher than normal number of fish deaths due to disease. The action was taken to reduce stress on remaining fish and ensure as many as possible successfully spawn later this year. A similar outbreak occurred on the East Lyn in 2012.
Symptoms shown by diseased fish include open lesions around the head and fungus on fins and other parts of the body. A detailed post mortem examination of a salmon carried out at the Agency’s National Fisheries Laboratory proved inconclusive. There were no signs of harmful pathogens and while affected skin tissue showed changes similar to the early stages of the fish disease, Ulcerative Dermal Necrosis (UDN), they were not typical of this condition.
Prolonged dry weather throughout August has meant few fresh fish have entered the river and there is no evidence to suggest the disease situation has improved.
‘We still aren’t sure of the cause of the fish deaths, but it is most likely to be due to a combination of factors, including environmental conditions. As a precaution, we have decided to keep the Watersmeet and Glenthorne fishery closed for the remainder of the season (until Sep 30),’ said Mike Holland for the Environment Agency.
In the meantime, the Agency will continue to monitor fish health and stocks on the River Lyn. Observations by fisheries officers suggest the majority of salmon that entered the river this year have either died or been affected by disease. Numbers of grilse (salmon returning to spawn after one winter at sea) have been especially low.
However, there is some good news. Monitoring of the upper reaches of the Lyn has revealed high numbers of young salmon (fry and parr).This indicates that spawning was successful last year despite the apparent loss of a high proportion of returning adults due to disease.
‘This is especially good news when you consider the extreme weather last winter and highlights the resilience of wild salmon and the high quality of habitat in the upper river,’ said Mike Holland.
The Agency-managed Watersmeet and Glenthorne fishery accounts for around 80% of fishing on the River Lyn. Owners of privately-owned fisheries on the river are being encouraged to extend their voluntary closures until the end of the 2013 season.
The brown trout fishery will remain open as normal until September 30.