OPTIMAL TIMING FOR 1ST FEEDING IN ATLANTIC SALMON (SALMO-SALAR L) ALEVINS - EFFECT OF DIFFERENT HATCHING SUBSTRATES CORRELATED TO GROWTH AND RNA AND DNA METABOLISM

The effects of different hatching systems on the timing of first feeding in Atlantic salmon alevins has been investigated. One alevin group was reared in traditional flatscreen incubators and first fed when two thirds of yolk mass was resorbed. The other alevin group was reared in astroturf incubators and first fed at swim-up. The outlet of the incubators was constructed in such a way that the alevins could swim directly into the first-feeding tanks. The astroturf-reared alevins showed better growth and had higher contents of RNA and DNA. Moreover, for this group the timing for first feeding was less critical compared to the flatscreen-reared alevins. By letting the salmon alevins have first feeding at swim-up, our sampling system provides a method for optimal timing for feeding which does not depend on the hatching conditions.