Meeting Abstract
1.10 Sunday, Jan. 4 Predation strategy in European pike-perch Stizostedion lucioperca: the role of hydrodynamic trail following HANKE, W.; Rostock University wolf.hanke@uni-rostock.de
The European pike-perch (Stizostedion lucioperca) is a piscivorous predator in the open water of lakes and slowly running rivers. Pike-perch prefer turbid waters and hunt mainly at twilight or at night. Although they feature remarkably well developed eyes, there are reports on blind, well-fed specimens (Krizhanovskij SG et al., 1953). I investigated the spontaneous prey capture behavior of Stizostedion in complete darkness to life prey and dummies, particularly considering the question whether pike-perch sense and use the vortex trail caused by fishes for prey detection. Four juvenile pike-perch (body length 17 to 24 cm) were kept in a shallow basin (3,6 m * 1,3 m, water level 13 to 25 cm) under an approximately natural day-and-night illumination cycle. In 14 sessions, 121 hours of pike-perch activity in total darkness were recorded on video tape using infrared illumination. Three to six prey fishes (Belica, Leucaspius delineatus, body length 3 to 6 cm) were introduced into the basin at the beginning of each session. Two loudspeakers generated acoustic noise (sound pressure > 0.5 Pa below 400 Hz) in 10 out of the 14 sessions. 118 scenes of interest, i.e. predator-prey interactions or the remarkable absence of a reaction to a prey at close range, were defined. No difference between sessions with or without acoustic noise was discernible. Thirty-five attacks started from within one body length without a clear deliberate approach from a distance (28 with acoustic noise). In three successful attacks, six vain attacks, and 8 interactions with no attack, the predator swam on the prey’s trail in a way that the shed vortices most likely aided in the orientation. However, although hydrodynamic trails of fish can last for minutes (Hanke et al. 2001, 2004), no scene was recorded that undoubtedly proved the use of an aged hydrodynamic trail far away from the prey.
