Young-of-the-Year Fish Community in Nine Lakes, Varying in pH, on the Canadian Shield

Abstract

In nine Canadian Shield lakes, seven with resident fish populations, the young-of-the-year (yoy) were first captured some 4 wk and more following the major spring depressions in pH. Since spawning of many resident species followed the spring freshet, yellow perch (Perca flavescens), darters, and many cyprinids sensitive to low pH would hatch and develop folowing the most serious spring changes in chemistry. Within a lake, the period of peak abundance occurred within a period of 2–9 wk during the 3 yr of study. Abundance of yoy was not strongly linked to lake pH or alkalinity. Diversity of yoy was strongly related to lake pH (r = 0.87) and alkalinity (r = 0.89). Monitoring the larval fish community appears to provide a responsive, reproducible measure of change for some of the fish communities sensitive to effects of acidic deposition and can be carried out with only moderate expenditure of time and resources.