The potential for natural reproduction of chinook salmon in the Chippewa River, Isabella County, Michigan

During 1992-1993, the Chippewa River in Isabella County, Michigan was evaluated as a possible site for natural reproduction by fall spawning chinook salmon.; A survey of 37 km of the river identified five chinook salmon redds. Survival of incubating salmon during embryonic and alevin life stages was determined by observing development of eggs planted in artificial redds located adjacent to natural redds. Parameters investigated were substrate composition, sedimentation, temperature, dissolved oxygen, and turbidity.; Results indicated that embryos developed well at all sites until hatch, when a significant reduction in alevin survival was observed in artificial redds downstream from an agriculturally degraded tributary. Alevin survival correlated negatively with increased sediments less than 0.125 mm in diameter. Potential spawning sites upstream from that tributary were degraded by algal growth and anoxic sediments and thought to be selectively avoided by spawning salmon. No evidence of successful natural reproduction was observed.