Reproduction biology of perch (Perca fluviatilis L.) in model Chabařovice Lake (North Bohemia, Czech Republic)

Using SCUBA divers we finished the most complex and most detail research on perch reproduction biology ever. We found that in Chabařovice Lake perch used at least seven different spawning substrates, particularly curly pondweed Potamogeton crispus, common reed Phragmites communis and worm weed Artemisia sp. However, while living submerged vegetation, although more abundant, was generally avoided, dead submerged vegetation was strongly preferred. It appears that dead vegetation is an ideal spawning substrate for perch since placement of the egg strands over those hard, complex three-dimensional structures ensures that the eggs remain well oxygenated 24 hours a day. The depths at which perch egg strands were deposited increased significantly during the spawning period (late April - early June) and basically corresponded to the position of 10-12°C water layers. Surprisingly, the depth of perch spawning was controlled also by the duration of the daylight period and finally by fish inner clock. At the beginning of perch spawning period also wind and waves influenced the depth distribution of egg strands. Factors influencing the selection of spawning sites were identified as wind inducing current, internal seiches, temperature instability of the water column and extreme displacement of water mass. Ignoring deeper strata while searching for perch egg strands (>3 m; as it was very common in previous works of both European and North American authors) may cause drastic underestimation of perch spawning success in lakes, since this fish is able to deposit its eggs to a depth of over 20 m.

Čech, M. - Peterka, J. - Říha, M. - Jůza, T. - Kubečka, J.: Distribution of egg strands of perch (Perca fluviatilis L.) with respect to depth and spawning substrate. Hydrobiologia. č. 630 (2009), s. 105-114.
Čech, M. - Peterka, J. - Říha, M. - Draštík, V. - Kratochvíl, M. - Kubečka, J.: Deep spawning of perch (Perca fluviatilis L.) in the newly created Chabařovice Lake, Czech Republic. Hydrobiologia. č. 649 (2010), s. 375-378.
Čech, M. - Peterka, J. - Říha, M. - Muška, M. - Hejzlar, J. - Kubečka, J.: Location and timing of the deposition of egg strands by perch (Perca fluviatilis L.): the roles of lake hydrology, spawning substrate and female size. Knowledge and Management of Aquatic Ecosystems. č. 403/08, s. 1-12.
Čech, M. - Vejřík, L. - Peterka, J. - Říha, M. - Muška, M. - Jůza, T. - Draštík, V. - Kratochvíl, M. - Kubečka, J.: The use of artificial spawning substrates in order to understand the factors influencing the spawning site selection, depth of egg strands deposition and hatching time of perch (Perca fluviatilis L.). Journal of Limnology. č. 71(1) (2012), v tisku.