Estimated population abundance of catchable signal crayfish (Pacifastacus leniusculus (Dana) ) and spiny-cheek crayfish (Orconectes limosus (Raf.) ) in Lake Pobledzie (northeastern Poland)
Krzywosz, T.; Ulikowski, D.; Traczuk, P.
Archiwum Rybactwa Polskiego 141: 141-146
In 2004, monitoring catches were performed on signal crayfish, Pacifastacus leniusculus (Dana) and spiny-cheek crayfish, Orconectes limosus (Raf.), in order to estimate the abundance of the catchable populations in Lake Pobledzie (northeastern Poland). Catches were performed using 58 Evo traps along a part of lake with an area of 1.65 ha. In catches conducted on September 6 and 7, a total of 479 specimens of signal crayfish and 29 spiny-cheek crayfish were caught, marked, and released. After twelve days, repeat catches were conducted during which 476 specimens of signal crayfish, including 66 marked specimens, and 36 specimens of spiny-cheek, including 5 marked specimens, were caught. The average total length of the caught signal crayfish was 11.7 plus or minus 1.06 cm (7.6-15.0 cm), while that of the spiny-cheek species was 9.3 plus or minus 0.65 cm (7.5-10.7 cm). The average catchable population abundance per unit of studied surface area was calculated at 2094 specimens ha-1 for signal crayfish and 127 specimens ha-1 for spiny-cheek crayfish. Taking into consideration that this method underestimates the population abundance of crayfish from the lower size classes, it is estimated that the actual catchable population abundance in Lake Pobledzie might be higher by about 25%.