Studies in the Development of the Rainbow Trout (Salmo Irideus)

Abstract

ABSTRACT The wet and dry weights of a selected population of rainbow trout eggs were determined at intervals from the 1st day after fertilization until the 84th day of incubation at 10° C. The alevin attains its maximum weight at the 65th day, the embryo some 10 days later. The heat production of egg and alevin rises until the 65th day and subsequently fluctuates violently. Fuel values of yolk and embryo samples were measured. The heat production is commensurate with the loss in the total fuel value of the system. Nitrogen excretion of eggs and alevin rises steadily throughout development. It seems probable that only the ammonia fraction is freely diffusible through the chorion. Determinations of the total nitrogen content of embryo and yolk samples demonstrate that the nitrogen excretion observed is sufficient to balance the loss in total nitrogen of the system. The fuel values and excretion measurements are shown to be in accord with the observed loss of dry materials by the egg-alevin system. The significance of this is discussed.