Application of otolith analyses to investigate broad size distributions ofyoung yellow perch in temperate lakes

摘要

Otolith analyses were used to back-calculate young-of-the-year (YOY) yellow perch Perca flavescens hatch-date estimates to interpret broad length distributions observed within a small Great Lake. Lake St. Clair, and a small inland lake, Lake Opinicon. during 1998. For the Great Lake. the earliest observed hatch date occurred 2 weeks after suitable water temperatures and latest hatch dates occurred the same week temperatures were considered too warm for spawning. For the inland lake. the earliest hatch date occurred 4 weeks after suitable water temperatures and the latest hatch dates occurred 2 weeks after the water temperatures were considered too warm for spawning. It is inferred that spawning in each lake had a duration of >9 weeks. This suggests that natural perch populations can protract their spawning season opportunistically under the appropriate environmental cues. During 1998, these cues involved a shortened winter, earlier spring, and slow warming to typical summer temperatures. caused by the El Nino-Southern Oscillation. Time of YOY hatch determined the absolute opportunity for growth and resulted in a match or mismatch with optimal foraging conditions and contributed to the development of the observed YOY length distributions.