holding
temperature during the breeding season influences final maturation and egg
qualiTy in common wolffish
H. Tveiten, S.E. Solevåg, H.K. Johnsen-2001
Journal of Fish Biology, 58(2): 374-385
Abstract:
Mature common wolffish, Anarhichas
lupus L., previously held at 8°C for several months, were
exposed to 4, 8 or 12°C throughout the breeding season
(November-January). Regardless of temperature, some females
ovulated in early-November, but thereafter ovulation
was delayed in the 8 and 12°C groups compared with
the 4°C group. Temperature experienced by the adult
fish also affected egg development and survival even
though eggs were incubated at a common temperature of
6°C. The percentages of normally cleaved eggs (at the
32-cell stage) and egg survival to the eyed stage
were significantly lower in the 12°C group (8%) than in
the 4°C (73%) and 8°C (48%) groups. The differences in
egg survival were also significant between the 4 and 8°C
groups. Egg survival was also influenced by the length
of time the broodfish had been exposed to the
different temperatures: at 4 and 12°C there were
significant positive and negative relationships, respectively,
between egg survival 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 that
both the timing of ovulation and egg quality
of common wolffish are affected by the temperature
experienced during the breeding season.
(Norwegian College of Fishery Science, University of
Tromsø, N-9037, Tromsø, Norway, Tel.: +47 77 64 44 89, e-mail: email:helget@nfh.uit.no)