Zoological Studies

Vol. 49 No. 2, 2010

Turning Night into Day: Effects of Stress on the Self-Feeding Behaviour of the Eurasian Perch Perca fluviatilis

Keno Ferter1 and Victor Benno Meyer-Rochow1,2,*

1Faculty of Engineering and Sciences, Jacobs University, Research II, D-28759 Bremen, Germany
2Department of Biology, University of Oulu, SF-90300 Oulu, Finland

Keno Ferter and Victor Benno Meyer-Rochow (2010) Effects of stress on the feeding behaviour of the Eurasian perch Perca fluviatilis were investigated.  Over a period of 32 d, the selffeeding patterns of a group of 4 fish were monitored with a light-dark cycle of 12:12 h.  As the perch could obtain food by triggering a feeding apparatus at any time, food availability likely did not govern the feeding activity pattern.  During the light phase, when the perch were exposed to an illumination of 2.4 W/m2, they were repeatedly (but at irregular times) disturbed through surface-transmitted vibrations and shadows.  Monitoring of the self-feeding pattern over a 24 h period showed that the fish changed their feeding activity from diurnal to nocturnal when exposed to this type of stress in combination with the relatively bright illumination during daytime hours.  In order to show that the perch associated the trigger with food and pulled it intentionally rather than randomly, the feeding apparatus was emptied while trigger activation was monitored for a further 6 d.  As soon as food was no longer available from the feeding apparatus the perch decreased their pulling activity until they had completely lost interest 6 d later.

Key words: Aquaculture, Demand feeding, Biorhythms, Food procurement, Vision.

*Correspondence: Tel:49-421-2003242.   E-mail:b.meyer-rochow@jacobs-university.de