Temperature experienced during vitellogenesis influences ovarian maturation and the timing of ovulation in common wolffish

Temperature treatment of common wolffish Anarhichas lupus during vitellogenesis affected the time of final maturation; ovulation in fish held at 8 and 12° C from mid‐April to October was about four and five weeks delayed, compared with a 4° C group. Fish in the 8° C group had significantly larger eggs than those in the 4° C and the 12° C groups, and a significantly higher egg production than fish in the 12° C group. Temperature treatment did not affect either fertilization rate or relative fecundity, but absolute fecundity was significantly lower in the 12° C group than the other groups due to poor growth of the fish at high temperature. This did not affect the numbers of spawning individuals. There was a trend towards lower egg survival to the eyed stage in the 12° C group compared to the 4 and 8° C groups, although the effect was not statistically significant. The results indicate that both the timing of final maturation and investment in ovarian growth in common wolffish are affected by temperature experienced during vitellogenesis.