Background to Lake Sturgeon Embryo Stage
As sturgeon hatch, the “free embryo” immediately burrows further into the substrate to find cover or refuge while utilizing yolk-sac reserves. At this stage, lake sturgeon embryos are negatively phototaxic, which means that they avoid light sources by hiding in rocky stream substrate. After their yolk-sac is absorbed, which usually takes up to 5 to 7 days depending upon temperature, the embryo begins exogenous feeding which is the onset of the larval period. As lake sturgeon begin exogenous feeding, they emerge from the substrate as larvae and disperse down stream to suitable larval rearing areas.
Summary of developmental features from hatch to complete yolk sac absorption used to determine developmental stage. LL – lateral line; CuD duct of Cuvier; ATC – anterior transverse commissure; FF – finfold; BV – network of blood vessels; YS – yolk sac; Rud. – rudiments; Fil. – filaments; S/I – stomach intestine; PA – pyloric appendage; P – posterior; A – Anterior; V – ventral; D – dorsal. Dettlaff et al. (1993)