Advanced ovarian development of Murray cod Maccullochella peelii peelii via phase-shifted photoperiod and two temperature regimes

Abstract

The timing and characteristics of reproductive development in adult female Murray cod exposed to a simulated seasonal photothermal cycle (14:45 to 09:45 daylight h; 12-26°C) (CONTROL) were compared to the development of females exposed to a three month phase-shifted (advanced) seasonal photothermal cycle (PHOTOTHERMAL) and to females exposed to a three month phase-shifted (advanced) photoperiod cycle in combination with constant temperature (19.5°C) (PHOTOPERIOD). Females in PHOTOTHERMAL and PHOTOPERIOD treatments reached maturity up to three (June) and four (May) months in advance of CONTROL fish (October), respectively. Biannual maturation was also observed in four PHOTOPERIOD females (13%..