Utilization of body stores in embryonated ova and larvae of two coregonid species ( Coregonus lavaretus L. and C. albula L.)

Abstract

1. 1. Developing eggs of whitefish ( Coregonus lavaretus L.) and vendace ( Coregonus albula L.) were kept at 1–2°C and some eggs taken gradually up to 8°C to provoke mass hatching of embryos. 2. 2. Wet weight, dry matter and the contents of lipid, protein and ash were measured in fish during the course of experiment. 3. 3. Dry matter content decreased gradually in whitefish eggs from 15.64 to 11.95% during 1 month at 1–2°C, whereas vendace eggs showed only a slight decrease from 16.27 to 15.53%. 4. 4. In both species protein content decreased but lipid increased when approaching the natural time of hatching. 5. 5. During delayed hatching at low water temperatures protein contributes to catabolism, whereas lipid content decreased only in the later phase of the experiment. 6. 6. Larvae starved for 10 days after hatching lost increasing amounts of dry matter (from 26.1 to 50.3% of body weight) and protein (from 18.7 to 45.9% of body weight) as they remained longer in cold water as embryos. 7. 7. A correspondence was found between assessment of metabolic utilization of body stores based on chemical analysis of fish body and previous work on oxygen consumption and nitrogen excretion.