REPRODUCTION AND SPAWNING IN WALLEYE (STIZOSTEDION-VITREUM)

The walleye (Stizostedion vitreum) is a North American mesothermal fre shwater teleost that spawns once each year in early spring. Walleye sp awn randomly over suitable substrates and do not provide any parental protection for eggs or juveniles. The majority of gonadal recrudescenc e in adult male walleye occurs in the autumn, and walleye testes conta in large numbers of viable spermatozoa from late autumn through the sp awning season. Adult female walleye exhibit group synchronous ovarian development, and similar to males, the majority of gonadal development occurs in the autumn. Evidence suggests that 17 alpha,20 beta-dihydro xyprogesterone is the maturational steroid in this species. Simple env ironmental manipulations coupled with injections of human chorionic go nadotropin can be used to advance spawning in walleye by up to 12 week s. To spawn and propagate walleye, hatcheries in North America use a w ide range of methods that have been developed to meet the needs and co nditions present at specific facilities.