S. Worischka, T. Mehner-1998
Journal of Fish Biology, 53 : 1050-1059
Abstract :
Since bioenergetics model for 0+ fish have seldom been validated by field consumption estimates, field-based and indirectly estimated daily food rations were compared in larval perch Perca fluviatilis and zander Stizostedion lucioperca. Field-based estimates were calculated with linear and exponential evacuation rates based on gut fullness data during a 24-h cycle, with hourly field samplings instead of the normally recommended 3-h intervals. Indirect calculations used bioenergetics modelling with variable activity multipliers (A). Field-based estimates of daily rations ranged between 0.21 and 0.27 g/g/day in perch (mean LT 13.1 mm) and 0.31-0.40 g/g/day in zander (mean LT 10.6 mm). The higher values were calculated by using the exponential model. Daily rations calculated by bioenergetics modelling with A=1 were only slightly higher than direct estimates in both species. However, if A values >1 were used, calculated daily rations were substantially higher than direct estimates. Estimates of daily ration based only on every third value ranged between 41 and 72% compared with 1-h intervals, mainly because of lower estimates of evacuation rate.
(Institute of Hydrobiology, University of Technology, D-01062 Dresden, Germany)