Egg production in Arctic charr ( Salvelinus alpinus L.) broodstock: effects of photoperiod on the timing of ovulation and egg quality

• Published in: Canadian Journal of Zoology
• Main Author: Gillet, C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1994
• Subjects: Animal Science and Zoology; Ecology, Evolution, Behavior and Systematics; Arctic; Arctic charr; Salvelinus alpinus
• Online Access: http://dx.doi.org/10.1139/z94-047; http://www.nrcresearchpress.com/doi/pdf/10.1139/z94-047

Arctic charr were subjected to different photoperiod manipulations applied at several stages of the reproductive cycle to advance or delay ovulation. Spawning was delayed by 6 weeks when the fish were subjected to long days (17 h light: 7 h dark) from midsummer. Ovulations were spread over a period of 2.5 months if fish were maintained under a long-day regime until spawning. When the long-day treatment was stopped in December, ovulations were synchronized to within 1 month. Long days early in the year followed by short days at the beginning of summer advanced spawning by 3 months. Immature, 20-monfh-old fish maintained in constant long days from 1 October started to spawn at the beginning of the following summer, i.e., 6 months before fish kept in a natural light period. The eggs produced in January by females with delayed ovulation were of better quality than those of fish kept in a natural day length in December. This improvement was probably due to a decrease in water temperature from 8 to 6 °C between December and January, since overripening of the ova was reduced when the temperature was decreased. It seems possible that by manipulating the photoperiod, viable eggs can be obtained from Arctic charr broodstock all year round provided the cold-water requirement of spawners is taken into account.