Digestive secretions of lake sturgeon, Acipenser fulvescens, during early development

Digestive secretions of lake sturgeon were analysed for 60 days post‐hatch. Three developmental phases were observed. During the yolk‐sac stage (days 1–16) the digestive system differentiated and digestive enzyme concentrations were low. Initiation of gastric secretion was concurrent with establishment of active feeding (days 14–18). Peptic and tryptic activities continued to increase thereafter. Amylolytic and lipolytic activities were highest during the larval feeding phase and then declined following metamorphosis of the larvae to juveniles (days 24–30). Changes in the digestive enzyme complement were age related, not dietarily induced, and appeared to correspond with the different feeding habits and, possibly, nutritional requirements of the distinct life history stages.