The future of flyfishing in vast parts of the country is at risk from the use of synthetic pyrethroid sheep dips. The health concerning organophosphate (op) dips led to the approval and use of what was billed as the safe alternative: synthetic pyrethroid (sp) dips. Both kill off sheep parasites such as sheep scab, blowfly, ticks and lice. But, cypermethrin, the active ingredient in sp dips, is up to 1000 times more toxic to aquatic life than diazinon, the basis of the op dips.
The Salmon & Trout Association (S&TA) has compiled damning evidence from the Environment Agency (EA) showing that even very small quantities of cypermethrin can wipe out invertebrates for up to 10 km of river. It routinely enters watercourses after sheep dipping operations.
It is particularly threatening for Wales, the Southwest, Northumbria, Cumbria, Kent, West Yorkshire and Devon – areas of intensive sheep farming and fleece processing.
With no flylife there is no flyfishing. Abundant flylife populations are vital to ensure the survival of the country’s aquatic ecosystems, which bring in over £ 4 billion pounds into rural and remote communities through angling.
Incidents of massive invertebrate deaths from SPs were first reported in April 1996, with a wipeout of invertebrates on 25 km of the river Earn in Scotland and, following the increasing number of pollution incidents and the documented evidence of the extreme toxicity of cypermethrin, S&TA first called for the withdrawal of synthetic pyrethroid dips in October 1997.
Since August 2003, there have been 57 sheep dip-related incidents in Wales alone, affecting 29 catchments. Most of these incidents have arisen from apparent routine use of cypermethrin. Detailed follow-up investigations over the last few years in these affected areas have shown severe declines in invertebrate biology caused by the contamination by sheep dip chemicals.
“Cypermethrin sheep dip pollution is devastating flylife populations across wide areas of the country,” Paul Knight, S&TA Director, states. “Although the government has brought in a number of measures for the use and administration of sheep dip, even when these best-practice guidelines are adhered to our evidence proves sheep dip pollution still occurs. Because the pollution is so toxic to invertebrates any pollution is unacceptable. We need to ban cypermethrin sheep dip now.”
There are very many ways in which the chemical cypermethrin can find its way into watercourses, even if best practice procedures are followed, Knight points out. Following dipping, residues of the chemical remain in the sheep’s fleece and may be lost to the environment through drips, sheep walking through watercourses, loss of wool, and in processing of fleeces. A further potential source arises from the disposal of used sheep dip. Sufficient resources to monitor the aquatic environment for sheep dip and all forms of pollution are necessary.
“The stark fact is that pollution is unavoidable due to the ‘sponge’ effect of wool. The chemical remains in the fleece until either it is washed directly off the animal, or the wool is processed. There must be no environmental impact from sheep dips, and the only way to achieve that is to ban their use, and support for farmers in the use of alternatives.”
Although cypermethrin is a highly efficient pesticide, nonetheless there are effective alternatives to sheep dip that are being used almost universally by sheep farmers in certain parts of the country such as Buckinghamshire. “We are aware that there have to be solutions to this issue that satisfy everyone involved, including farmers,” Paul Knight says. “Given the dangerous toxicity of SPs and the practical inability of controlling their after-effects, the S&TA is now leading a vigorous lobby for their total, and immediate, ban.”
