Fluctuations in fyke-net catches during the spawning period of the Eurasian perch ( Perca fluviatilis) in the Rimov Reservoir, Czechoslovakia

Abstract

The perch spawning stock catch (1985–1988) of the Rimov Reservoir was studied using Rimov fyke-nets and Klicava traps. Spawning and an increased catch were found in the tributary area 1 week earlier than in the main waterbody. The peak catches moved from depths of 3–4 m to the surface during the spring homothermy. After the development of thermal stratification, the peak catch moved to depths with a temperature range of 8–12°C. Catch per unit effort decreased during the second half of the spawning period but shifting the fyke-nets to depths where spawning activity was maximum increased the total seasonal catch by at least 100%. At the end of spawning, the peak activity was found at 6–9 m. Normal spawning stock is characterised by a strong predominance of males in the catch of the fyke-nets; postspawning females predominate in the later catches in shallow areas. Catches in the fyke-nets in the formerly wooded areas were more than four times higher than the catches from areas without tree stumps.