RELATIONSHIP BETWEEN YEAR-CLASS STRENGTH FOR GOLDEYES AND SELECTED ENVIRONMENTAL VARIABLES DURING THE FIRST YEAR OF LIFE

I investigated the relationships between year-class strength and selec ted environmental variables for the migratory population of goldeye Hi odon alosoides of the Peace-Athabasca delta, Alberta, Canada. Year-cla ss strength was highly variable from year to year. Goldeyes from the 1 971 year-class dominated the catch (up to 87%) in the 1970s, and other dominant year-classes (>25% of the catch) developed in 1982 and 1989. The 1985 year-class failed completely. On average, dominant or abunda nt year-classes (>5% of the catch) occurred about three times per deca de. Year-class strength was related to the number of warm days (mean d aily temperature >15 degrees C) from May 1 to July 31, the period that covers the time from the spawning migration to the development of a 5 7-mm, 1.9-g juvenile goldeye (r = 0.57, P < 0.01). The semibuoyant egg s and larvae of goldeyes were present in the delta primarily from May 22 to June 20. A linear relationship was not evident between year-clas s strength and wind intensity during this 30-d period (r = -0.09). How ever, dominant and abundant year-classes usually developed in those ye ars when this 30-d period was both warm and calm (wind intensity usual ly <20 km/h during the day). Year-class strength was not related to di scharge of the Peace River, the winter habitat of goldeyes, or to wate r levels in Mamawi and Claire lakes, the spawning and rearing habitats . Density-independent mechanisms regulate recruitment in the Peace-Ath abasca delta population of goldeyes.