Ekologija, morfometrija, polni dimorfizam i indeksi kondicije riječnog raka Astacus astacus (Linnaeus, 1758) iz rijeke Oskove

The research encompassed the sample of 13 crayfish specimens of Astacus astacus species (7 males and 6 females). Crayfishes were sampled using LiNi traps during 2016. The following morphometric characteristics were analyzed: total body length (TBL), weight (W), claw length (CLL), ength of the claw palm (CPL), length of the claw finger (CFL), claw width (CLW), claw height (CLH), carapace length (CPL), , rostrum length (ROL), rostrum width (ROW), head length (HEL), head width (HEW), width at the cervical groove (CGW), carapace width (CPW), carapace height (CPH), areolar length (ARL), areolar width (ARW), width of the carapace at the hind edges (CEW), abdomen length (ABL), abdomen width (ABW, at the second abdominal segment) and abdomen height ABH, at the second abdominal segment), and telson length and width (TEL, TEW). The mean body length was 88.27 mm (± SD 22.52; min. 69.50 mm; max. 132.60) in males and 81.91 mm (± SD 16.33; min. 62.50 mm; max. 97.16 mm) in females. The mean recorded body weight was 24.39 g (± SD 15.82; min. 12.20 g; max. 54.60 g) in males and 17.97 g (± SD 10.04; min. 8.00 g; max. 28.20 g) in females. Using the linear regression method, a positive correlation was found between body length and weight(♂ R2=0.9292; ♀ R2=0.9288), body weight and claws length (♂ R2=0.9193; ♀ R2=0.6946), as well as carapace width and body length (♂ R2=0.8496; ♀ R2=0.8939). According to Mann-Whitney U test there is insignificant statistical difference in examined morphometric characters between sexes. The calculated values for Fulton’s condition factor and the Crayfish constant indicate that the males are in better fitness, which is in line with the results of previous research in Europe. Data presented in this paper can serve as a basis for further research of Astacus astacus in this area.