Effects of Elevated Thermal Regimes on Survival of Rainbow Trout ( Salmo Gairdneri) Alevins

Abstract

Embryos of fall spawning rainbow trout were incubated and alevins reared under thermal regimes characteristic of ambient winter nearshore Lake Ontario and elevated thermal regimes 2 and 5C° warmer than ambient. Embryos incubated under elevated thermal regimes hatched and attained 50% swim-up sooner than embryos incubated under the ambient thermal regime. In general, mortality of alevins at 21 and 28 days after swim-up was low for all rearing thermal regimes. The generally low mortality of alevins incubated and reared under the various thermal regimes suggests that rainbow trout alevins have fairly broad thermal tolerances when food is provided to excess.