The effects of alterations in photoperiod on ovarian development and spawning time in the rainbow trout (Salmo gairdneri)

Abstract

The present study investigates the changes in serum oestradiol 17p, total calcium and phosphoprotein (as a measure of vitellogenesis) under a normal seasonal 12 month photoperiod cycle, normal yearly cycles compressed into 9 and 6 months, and a constant 12 hour light/12 hour dark regime and the effects of these experimental photoperiod regimes on the times of spawning of both male and female rainbow trout.