Abstract
Trout population densities decline dramatically in the Clark Fork River from nearly 2,000 catchable brown trout per mile just downstream of mine waste settling ponds to 50 trout Instream toxicity tests (1986-89), and analyses of metals in fish organs (1989) were conducted in various river reaches to try to understand how metals influence trout density patterns.
Instream toxicity tests with swim-up stage rainbow trout fry demonstrate that river water induces chronic mortality during spring runoff when metals concentration, particularly copper, exceed chronic criteria for protection of aquatic life. Concentration of copper in livers of adult brown trout (salmo trutta) are higher than those in laboratory fish populations exposed for several generations to chronically toxic concentrations of copper. Both acute and chronic stress from metals, particularly copper, are implicated as contributing to poor fish production in the Clark Fork.
Start Date
20-4-1990 11:20 AM
End Date
20-4-1990 11:40 AM
Document Type
Presentation
Ambient Toxicity Assessments of Clark Fork River Water-Toxicity Tests and Metals Residues in Brown Trout Organs
Trout population densities decline dramatically in the Clark Fork River from nearly 2,000 catchable brown trout per mile just downstream of mine waste settling ponds to 50 trout Instream toxicity tests (1986-89), and analyses of metals in fish organs (1989) were conducted in various river reaches to try to understand how metals influence trout density patterns.
Instream toxicity tests with swim-up stage rainbow trout fry demonstrate that river water induces chronic mortality during spring runoff when metals concentration, particularly copper, exceed chronic criteria for protection of aquatic life. Concentration of copper in livers of adult brown trout (salmo trutta) are higher than those in laboratory fish populations exposed for several generations to chronically toxic concentrations of copper. Both acute and chronic stress from metals, particularly copper, are implicated as contributing to poor fish production in the Clark Fork.