ESTIMATED POPULATION ABUNDANCE OF CATCHABLE SIGNAL CRAYFISH (PACIFASTACUS LENIUSCULUS (DANA)) AND SPINY-CHEEK CRAYFISH (ORCONECTES LIMOSUS (RAF.)) IN LAKE POBŁĘDZIE (NORTHEASTERN POLAND)
Tadeusz Krzywosz, Dariusz Ulikowski, Piotr Traczuk
Department of Lake Fisheries, The Stanisław Sakowicz Inland Fisheries Institute in Olsztyn, Poland
ABSTRACT. 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 Pobłędzie (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 ± 1.06 cm (7.6-15.0 cm), while that of the spiny-cheek species was 9.3 ± 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 Pobłędzie might be higher by about 25%.
Key words: SIGNAL CRAYFISH (PACIFASTACUS LENIUSCULUS), SPINY-CHEEK CRAYFISH (ORCONECTES LIMOSUS), TRAPPING, RECAPTURE
Dr hab. Tadeusz Krzywosz, Instytut Rybactwa Śródlądowego w Olsztynie, Zakład Rybactwa Jeziorowego, ul. Rajska 2, 11-500 Giżycko, Tel./Fax: +48 (87) 4283882;