Seawater challenge testing of coho salmon smolts following exposure to roundup® herbicide

Abstract

Concentrations of Roundup® herbicide of up to 10 times those encountered in the environment immediately after aerial application (2.78 mg/L) did not affect 24–h seawater survival; nor did plasma sodium concentration, hematocrit or growth in 10-d exposures with yearling coho salmon (Oncorhynchus kisutch). Similarly, no abnormal responses were noted when a 10-d freshwater recovery period was provided between the herbicide and seawater exposures. These results indicate that the application of Roundup at the manufacturer's recommended use-rates for forestry management will not adversely affect the ability of coho salmon smolts to adapt to seawater and to osmoregulate normally.