Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 6983
Title: Avoidance chamber responses of mayfly nymphs exposed to eight herbicides
Author: Leroy C. Folmar
Publication Year: 1978
Journal: Bulletin of Environmental Contamination and Toxicology
Volume: 19
Issue: 1
Pages: 312-318

Avoidance reactions of rainbow trout fry exposed to nine herbicides that may be used in or near irrigation systems were described by Folmar (1976).  Irrigation canals that contain viable sport fisheries also support populations of aquatic insects, which serve as a primary source of forage for the fish. In a survey of the Colorado Big Thompson Irrigation Project, Otto (1975) reported that six orders of aquatic insects were collected at several sampling stations.  Because movement (stream drift) or death of the insects may have a deleterious influence on the nutrition of a resident fishery, it was important to determine whether a representative insect (Ephemerella walkeri) would, like fry of rainbow trout (Salmo gairdneri), avoid some of the most commonly used herbicides.  This information could be applied to natural waters, since fractions of the treated water may be returned to receiving streams, either as return flow from irrigated fields or as unused irrigation water. 

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