Dependence of Coregonus albula embryogenesis rate on the incubation temperature

Eggs stripped from Coregonus albula were incubated at different constant temperatures. The duration of embryogenesis varied from 183 days at 1.1°C to 45 days at 9.9°C. We describe the course of embryogenesis using 16 easily recognizable developmental stages (DS j). Development rate (DR j) for any given stage (DS j) is expressed as the reciprocal of time (in days) from fertilization to attainment of a given developmental stage. The generalized equation relating rate of development to stages DS j with respect to temperature (x) is

The values of DR to the “eyed egg” stage and to 50% hatch, expressed as percentage per day of the total development period, were computed and tabulated for temperatures ranging from 0.1 to 9.9°C. To verify the derived regression model we observed the course of embryogenesis of C. albula eggs incubated in a commercial hatchery at fluctuating temperatures. The observed times of attainment of the successive developmental stages were compared to the predicted times based on mean daily water temperatures. The time observed agreed well with times predicted by the model; the only exception was the time of hatching, which was systematically overestimated (5 to 7 days) by the model. This was possibly due to the influence of dissolved oxygen on the time course of hatching processes, which was not considered in our regression model.