The Development of Brook Trout (Salvelinus fontinalis Mitchill, 1814) Embryos During the Yolk Sac Period


Abstract: The growth rate during yolk absorption, yolk conversion efficiency, dry weight and water contents of brook trout (Salvelinus fontinalis Mitchill, 1814) larvae were observed and the relationships between degree-days were evaluated. While the mean wet weight was 72.45 ± 5.58 mg (n = 10) at hatching and reached 98.85 ± 6.22 mg just before the swim-up stage, the mean dry weights of the body and yolk sac were 2.70 ± 0.41 and 23.33 ± 0.59 mg at hatching and 9.49 ± 1.27 and 12.46 ± 1.14 mg at swim-up stages, respectively. The mean body dry matter and water content of the larvae were 36.04% and 63.96% at hatching and 19.22% and 80.78% at swim-up stages, respectively. Considering the relationships between larval development and degree-days, dry yolk and total larval weights and dry matter of the larvae decreased, while dry body weight and water content increased with degree-days. The growth of larva, yolk sac absorption and yolk conversion efficiency were calculated as 0.235 mg/day, 0.477 mg/day and 0.50, respectively. These results can be used for environmental and husbandry manipulations to influence rates of larval development and mortality, and to increase the productivity of hatcheries.

Keywords: Brook trout, Salvelinus fontinalis, larval development, yolk conversion efficiency, growth

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