Journal of Fisheries and Life Sciences

Author(s): Ahmadi

Abstract: American crayfish (Procambarus clarkii) supports beneficially for aquaculture industry and is also considered as invasive species due to their adverse impacts on the native species and ecosystems. This study aimed at investigating Phototaxis mechanism, length-weight relationship and condition factor of P. clarkiifrom the pond. Crayfish were collected using the four light traps with different light intensities (215-2,050 lx). The traps made of 6-mm iron frames (60´50´25 cm) and black 3/5 inch hexagonal mesh wire. Data on body sizes and sex of crayfish were analyzed. A total of 256 specimens (74-112 mm TL) comprising 157 males (61%) and 99 females (39%) were collected. There were no significant differences in the average total length (TL), carapace length (CL), chelae length (ChL) and weight (W) of males or females among the four traps (p > 0.05). The CL/TL and ChL/TL ratios and condition factor of males were considerably higher than females (p < 0.001). Males showed negative allometric growth (b = 2.757), while females exhibited isometric growth (b = 3.002). The positive group responses of crayfish were more pronounced at 90-94 mm TL and 20-29 g weight. P. clarkii positively responded to different light intensities. The light traps can be used to improve the harvesting procedures of commercial aquaculture.