Emergence chronology of brook charr, Salvelinus fontinalis, alevins in an acidic stream

The emergence chronology of brook charr alevins in the Chikanishing River, Ontario, Canada and the concurrent changes in stream chemistry resulting from acidic snowmelt runoff were examined during the spring, 1986-1988. Emergence patterns were similar among years with the most intense emergence (> 70%) occurring during the declining stream discharge following the spring flood. This period coincided with stream pH depressions (minimum pH 5.2) in 2 of 3 years, suggesting emergence behaviour frequently subjects the earliest free-swimming life interval of brook charr to episodic acidification events.