Vaz-Serrano, J., Åberg, M., Gjøen, H.M, Steffensen, J.F. and Höglund, E.

Abstract: In this study we investigated the relation between larval development and metabolic rate in Atlantic salmon (Salmo salar, L.). Individual weight-specific oxygen consumption (VO2) and yolk consumption were studied in six out of 91 families, the three families with earliest and the three families with latest time to hatch. Measurements were done on two occasions, at 570-580 (T1) and 600-610 (T2) day degrees from fertilization. Generally, VO2 increased and yolk was consumed between T1 and T2. Late hatching larvae had higher VO2 compared to early hatching individuals at T1, but not at T2. Early and late hatchers were equally developed at T1and T2. Intra-family variation in time to hatching, suggests inherited parts of individual developmental rate. That late hatching larvae reached same level of development and had higher metabolic rate in T1 suggests that these inherited differences can be even out by accelerated post hatch growth.