Patterns and reasons of different pelagic behaviour of perch fry: novel insight into the declared ecological plasticity of a species

Project No. 206/06/1371

Applicant: RNDr. Martin Čech, PhD.

Financial support: Czech Science Foundation

Duration: 2006-2008

The project follows up the recent finding that juvenile perch Perca spp. are able to create sympatric ecological groups with different behaviour. The epipelagic fry (EPF) spent the whole 24 hours in the epilimnion whereas the bathypelagic fry (BPF) performed diel vertical migrations (DVMs), being in the epilimnion during the night and migrating into the cold hypolimnion during the day. The project aims on better definition of newly discovered groups, temporal and spatial patterns of their separation, reasons of sympatric existence of EPF and BPF, profitability and fate of individual strategies, cues of DVMs, predation pressure on pelagic perch fry, gradients in perch fry abundance, age and size distribution as well as perch egg strands deposition on the longitudinal profile of the reservoir. New approaches including more quantitative and extensive acoustic and net sampling, SCUBA diving, molecular genetics, histology and parasitology will be used. Grouping behaviour of juveniles of close relative, zander, Sander and ruffe, Gymnocephalus will be also investigated and the project is likely to bring new understanding into early behaviour of perciform fish.