US salmon threat

Coho salmon can be directly and indirectly affected by lethal or sublethal concentrations of pesticide residues in surface water, according to a report by the US Northwest Coalition for Alternatives to Pesticides (NCAP). With the exception of California, regulatory agencies do not know what pesticides are used throughout the coho salmon range. Sampling for residues by regulatory authorities is not always conducted in periods most likely to detect residues and at the highest concentration levels that are likely to appear. Pesticides referred to include oxydemeton-methyl, chlorothalonil, diazinon and 2,4-D. Pesticide application practices that are routinely used to protect surface water from contamination are at best only partially successful at keeping pesticide residues out of streams.
    NCAP outlined the following recommendations: reducing or eliminating pesticide use; establishing pesticide-free zones in critical coho habitat; carrying out comprehensive pesticide use reporting in all states within coho habitat; improving sampling and methodology; taking into account the uncertainty that exists about the potential effects of pesticides on coho when setting water quality standards.

Toxic water: A report on the adverse effects of pesticides on Pacific coho salmon, Norma Grier, Erik Clough and Anna Clewell, NCAP, 1994.  PO Box 1393, Eugene, OR 97440, US.

[This article first appeared in Pesticides News No. 28, June 1995, page 26]