Comparison of seasonal activity of the lake minnow, Eupallasella percnurus (Pall.), and crucian carp, Carassius carassius (L.), in small water bodies in northern Poland
This paper presents preliminary results of a comparison of the seasonal activity of lake minnows, Eupallasella percnurus (Pall.), and crucian carp, Carassius carassius (L.), in a few small water bodies. Field studies were conducted based on catches made with baited traps in periods without ice cover from April to December 2006. E. percnurus became active earlier than did C. carassius and their period of intense activity was longer. The first E. percnurus appeared in the traps in early April when the ice was still melting, and these fish were caught at a temperature range of 3.5-29.2°C. C. carassius were caught most abundantly in the beginning of May at temperatures from 15°C; this species was usually noted in traps at a narrower, but higher, temperature range in comparison with the E. percnurus. Additionally, the activity of both these species was similar with regard to weather conditions; both species were less active on cloudy days and when atmospheric pressure was increasing.