Environment Agency briefing to water users in Devon and Cornwall – Salmon and sea trout mortalities.
19.07.2013
This year we have received an increased number of reports of Atlantic salmon and sea trout showing signs of fungal infections in a number of rivers across England. The increase in reports currently appears to be focused in the South West, with mortalities of affected salmon and sea trout primarily being seen on the River Lyn. These conditions are natural and normally affect low numbers of fish returning to freshwater. We are monitoring the situation here closely, as well as in other parts of the country and with the relevant agencies in Scotland and Wales.
River Lyn Fishery:
Following the salmon and sea trout mortalities experienced on the East Lyn, we have taken the decision to close the salmon and sea trout fishing on our Watersmeet & Glenthorne fishery. We have encouraged other riparian owners on the river to do the same on a voluntary basis.
We have taken this decision as we are concerned that the loss of a high proportion of these early run fish (which are typically the largest) may have a significant impact on overall spawning success for 2013/14. These measures are necessary to reduce exploitation and stress on the remainder of the returning adult population, something which is of particular concern in periods of low flows and increased water temperatures.
Investigations into the cause of the mortalities are on-going, but early results from the tests conducted on the sample taken from the E. Lyn have been negative for a range of viral diseases. We are currently awaiting results from further analyses. We have no reason to believe that the current issues are caused by an infectious agent, so fishing for brown trout will remain open, but as a precaution we are reminding all river users to continue to follow biosecurity best practice before and after taking part in activities in the river.
Other rivers in Devon & Cornwall:
We are aware that lower numbers of mortalities have occurred elsewhere in Devon & Cornwall (as well as some other parts of the country) and a number of fish in other rivers are showing signs of disease. Some rivers appear to be more affected than others, however to the best of our knowledge none have been affected to quite the same scale as the E. Lyn this year. In order for us to establish how widespread this issue is across the region we are asking angling groups, riparian owners and other river users tell us about any sightings of dead or diseased fish. These people are our eyes and ears on the river and play a vital role in reporting sick fish. Having the best available evidence will enable us to assess whether this is an increasing issue across our area and will allow us to consider this in relation to on-going low flows and increasing water temperatures.
We will continue to work with river users to make informed and reasoned management decisions to balance conservation, sporting and community needs.
Biosecurity best practice:
All equipment should be clean, dry and disinfected before moving to different water. This can either be done by thorough drying in sunlight or with the use of specific disinfectants. We have produced a useful fact sheet on the disinfection of angling equipment (‘Disinfecting fishing tackle’) which can be accessed here:
http://www.environment-agency.gov.uk/research/commercial/32870.aspx