The effects of temperature and different food organisms on the rate of gastric evacuation in perch (Perca fluviatilis)

SUMMARY. The rate of gastric evacuation in perch Perca fluviatilis was studied at different mean temperatures (range 4.0–21.7°C). Gastric evacuation rates were empirically described by an exponential function and the relationship between the instantaneous evacuation rate (R) and temperature was also exponential. Evacuation rates were not significantly different (P > 0.1) for the following food organisms: Gammarus pulex, Chaoborus, chironomids and zooplankton. The effects of temperature, different food organisms and fish size on the evacuation rates in different fish species are discussed.