Holding temperature during the breeding season influences final maturationand egg quality in common wolffish

Mature common wolffish. Anarhichas lupus L., previously held at 8 degrees C for several months, were exposed to 4, 8 or 12 degrees C throughout the br eeding season (November-January). Regardless of temperature. some females o vulated in early-November, but thereafter ovulation was delayed in the 8 an d 12 degrees C groups compared with the 4 degrees C group. Temperature expe rienced by the adult fish also affected egg development and survival even t hough eggs were incubated at a common temperature of 6 degrees C. The perce ntages of normally cleaved eggs (at the 32-cell stage) and egg survival to the eyed stage were significantly lower in the 12 degrees C group (8%) than in the 4 degrees C (73%) and 8 degrees C (48%) groups. The differences in egg survival were also significant between the 4 and 8 degrees C groups. Eg g survival was also influenced by the length of time the broodfish had been exposed to the different temperatures: at 4 and 12 degrees C there were si gnificant positive and negative relationships, respectively, between egg su rvival and the number of days for which the female had been exposed to the given temperature prior to ovulation. Temperature experienced by the female did not affect egg size, relative egg weight, fertilization rate, relative fecundity or the number of ovulating individuals. The results indicate tha t both the timing of ovulation and egg quality of common wolffish are affec ted by the temperature experienced during the breeding season. (C) 2001 The Fisheries Society of the British Isles.