Size relations and yolk utilization in embryonated ova and alevins of Atlantic salmon Salmo salar L. in various combinations of temperature and dissolved oxygen

• Published in: Canadian Journal of Zoology
• Main Authors: Hamor, T., Garside, E. T.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1977
• Subjects: Animal Science and Zoology; Ecology, Evolution, Behavior and Systematics; Atlantic salmon; Salmo salar
• Online Access: http://dx.doi.org/10.1139/z77-242; http://www.nrcresearchpress.com/doi/pdf/10.1139/z77-242

Relations among weight (W), surface (S), and volume (V) for freshly fertilized water-hardened Atlantic salmon ova from 5 to 7 mm in diameter are: S = log V 2 /3, S = 1.21 log W, and V = W/1.2.Fresh weights remained relatively constant from fertilization to the establishment of blood vessels in the yolk sac. Subsequently, there was a rapid increase to 110%, followed by a gradual decline to 105% shortly before hatching. Large blastodiscs weighed 1.2 mg and embryonal weight increased very gradually until late prehatching stages, when growth was accelerated rapidly. Embryos, at hatching, after continuous incubation at 5 and 10°C and three levels of dissolved oxygen, varied from 22.1 mg (5 °C, 100% air saturation) to 11.9 mg (5 °C. 30%) and From 14.5 mg (10 °C. 100%) to 10.0 mg (10 °C, 30%).Cumulative and mean daily yolk depletion declined with lowered oxygen supply, but they were considerably greater at 10 °C than at 5 °C. Gross conversion ratios (including uptake of exogenous materials) indicate that yolk is used more efficiently at 5 °C, and 100% air saturation. Alevins, kept in their original environments, became more efficient than they were in their encapsulated state, and, at 10 °C. 100% air saturation, they overtook those at 5 °C before the completion of yolk absorption. Those in lower oxygen supplies continued to lag, at both temperatures.