Federal researchers say two widely used pesticides harm many endangered fish species

By April Ehrlich (OPB)
March 22, 2023 1 p.m.

Carbaryl and methomyl were found to jeopardize endangered Chinook and coho salmon, among others

Federal researchers have found that two widely used pesticides significantly harms endangered Northwest salmon and steelhead species. The opinion could lead to a change in where and how the pesticides can be used.

The National Marine Fisheries Service issued a draft of its biological opinion Thursday concluding that continued use of insect-killing chemicals containing carbaryl or methomyl likely jeopardizes dozens of endangered fish species — including Chinook salmon, coho salmon, sockeye, and steelhead in the Columbia, Willamette, and Snake rivers.

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Carbaryl and methomyl are insecticides commonly used on field vegetables and orchard crops. Both are used on agricultural land across the Willamette Valley, the Columbia River Gorge, and southeastern Washington, according to federal data.

The draft opinion says carbaryl is likely to jeopardize 37 listed species and methomyl is likely to jeopardize 30 listed species, and both are likely to harm or destroy many areas designated as critical habitat for endangered species. The fisheries service recommends either prohibiting the chemicals within 300 meters (about 325 yards) of species’ habitat or implementing mitigation practices, like expanding vegetation ditches as buffers or using tools that reduce runoff.

A coho salmon makes its way up Cedar Creek on its way to the Sandy fish hatchery.

A coho salmon in spawning colors.The National Marine Fisheries Service says that continued use of insect-killing chemicals containing carbaryl or methomyl likely jeopardizes dozens of endangered fish species — including Chinook salmon, coho salmon, sockeye salmon, and steelhead in the Columbia, Willamette and Snake rivers.

Rick Swart / Oregon Department of Fish and Wildlife

Under the Endangered Species Act, the Environmental Protection Agency must ensure the pesticides it registers for use don’t jeopardize federally listed endangered or threatened species, or harm their critical habitats. The agency had previously registered both of these pesticides but opened a new review after a lawsuit from the Center for Biological Diversity. The agency first conducts a biological evaluation to determine if a pesticide may affect these species or habitats. In its initial assessment of carbaryl and methomyl, the EPA found that carbaryl is likely to harm 91% of all endangered plants and animals and methomyl is likely to harm.

The agency then consults with the fisheries service and the U.S. Fish and Wildlife Service to pursue more in-depth biological opinions. The wildlife service will issue its own opinion pertaining to non-marine plant and animal species including amphibians, birds and reptiles.

The fisheries service’s draft opinion is open to public comment until May 15. After the public comment period closes, the EPA will provide official comments to the fisheries service for consideration in developing its final opinion.

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