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Pesticide brew kills salmon
Fishery managers could decide next week to close West Coast salmon fisheries for the first time ever. The shut down stems from a major collapse in salmon stocks all along the Pacific coast.
Most scientists blame 'broad scale ocean survival problems' as the main cause for the crisis. But the federal government may be grossly underestimating the hazard that pesticides pose to the fish.
Chemicals are routinely sprayed on crops and livestock and wash off into waterways. Past studies have looked at the effects of single pesticides. However, half of the Northwest waters sampled by the U.S. Geological Survey contain six or more pesticides - and new research shows that they make a lethal mix.
Zoologist Nathaniel Scholz at the NOAA lab in Seattle exposed juvenile salmon to a cocktail of four or more pesticides at a time. The tests showed that the chemicals interfere with brain transmissions in salmon and harms their ability to feed. Even at the lowest concentrations, the fish became extremely sick.
The pesticide chlorpyrifos was especially lethal. It is widely used to control cockroaches and fleas in homes, to control ticks on livestock and as a pesticide spray on crops. Because there is a great deal of information about where pesticides are sprayed, it may be possible to estimate the impact on fish.
Scholz said that given the hundreds of millions of dollars being spent to help salmon stocks recover, it is crucial to consider the biggest threats posed by pesticides. The story 'Pesticide Brew Spells Trouble for Salmon' is in ScienceNOW Daily News.
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