Environmental Regulation of Spawning-Period in an Autumn-Spawning Bitterling Pseudoperilampus typus

Abstract

Autumn-spawning bittering Pseudiperilampus typus were kept under several combinations of photoperiod and temperature regimes at different phases of their annual reproductive cycle. In early autumn, the gonads developed rapidly under short photoperiod (12L) regardless of temperature. In early winter, the gonads apparently regressed under low temperature (8-12°C) in spite of adequate photoperiod regime (10L). females kept under favorable photoperiod and temperature regime (19°C-10L) continued ovulation cycle much longer than natural spawning period, nevertheless this cycle finally terminated.
It is concluded that the spawning period of P. typus is initiated by the shortening daylength in autumn, and is terminated by the lowering temperature in winter. Furthermore, autonomous termination of spawning under artificial conditions can suggested.