FEEDING RHYTHM AND GASTRIC-EMPTYING IN TH E PIKE (ESOX-LUCIUS L.) DURING THE FEEDING CHANGES BELOW ONE-YEAR OF AGE

The gastric emptying and the feeding rhythm have been studied with you ng pike below one year of age according to the natural progressive cha nges in their feeding process (planktivorous, entomophagous, ichthyoph agous). The gastric emptying has been followed along with prey that ar e to be encountered by pike in their natural environment. In general, linear and logarithmic equations best describe the gastric emptying. T he effects of the temperature and of the size and the nature of the pr ey upon the gastric emptying are discussed. Pike do not digest chitin well. The evolution of the digestion of chitinous prey is given. At ev ery feeding stage, pike display a day-time hunting activity. Moreover, the feeding rhythm is clearly bi-phasic at the planktivorous stage.