Reconditioning and Reproductive Responses of Atlantic Salmon Kelts ( Salmo salar ) to Photoperiod and Temperature Manipulation

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Authors: Johnston, C. E., Farmer, S. R., Gray, R. W., Hambrook, M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1990
• Subjects: Aquatic Science; Ecology, Evolution, Behavior and Systematics; Atlantic salmon; Salmo salar
• Online Access: http://dx.doi.org/10.1139/f90-079; http://www.nrcresearchpress.com/doi/pdf/10.1139/f90-079

The reproductive cycle of reconditioned Atlantic salmon can be manipulated with light and temperature. Wild Atlantic salmon (Salmo salar) kelts held in freshwater and exposed from late December 1986 to a simulated natural photoperiod (NP) and a regime of two 6-mo seasonally accelerated light increases and decreases (2CP) reconditioned. Fifty-six percent of NP females spawned by early November 1987, 1 mo later than virgin wild females. No 2CP females spawned by December 1987. However, all 2CP females transferred in December 1987 to natural photoperiod and 7 °C water released eggs by June 1988. NP females that spawned showed seasonal peaks in cholesterol in August, triglycerides and calcium in September, and alkaline phosphatase in November; NP and 2CP females that failed to spawn showed no such changes. Alkaline phosphatase activity and calcium concentrations were linearly related to increasing oocyte diameter (but not oocyte number), and were good predictors of sex and oocyte development. Forty-two percent of 2CP males matured and released sperm in mid-August, 1 mo earlier than NP males or a virgin wild group. Twenty-three percent of 2CP males did not mature. Males showed significant differences in blood parameters between regimes and between spawners and nonspawners, but the levels were never as high as maturing females.