Determination of suitable trap type for the Caspian crayfish, Astacus leptodactylus eichwaldi, in Anzali coastal area, Iran

The efficiency of different types of traps for catching of the Caspian Sea crayfish, Astacus leptodactylus eichwaldi, was investigated from Mar. ۲۰۰۲ to Feb. ۲۰۰۳. Totally ۵۶ traps of four most commonly used types, "Rectangular trap", "Round trap", "Opera house trap" in two colors of "black" and "blue", and "Fathoms plus" only in black were installed in depths of ۳۵, ۴۵, ۵۵ and ۶۵ meters along two transects in Anzali coastal area. The results revealed no significant differences (p≥۰.۰۵) in the average length; weight and sex ratio among the crayfish in different months and applied traps. However, significant differences (p<۰.۰۵) in CPUE of different traps in various months of the study year were observed. Mean annual of CPUE in Opera house traps "blue" was the greatest (۵.۰۹±۰.۲۹) and the lowest was found in "Fathoms plus" traps (۰.۲۸±۰.۰۵). In general; all blue color traps performed better catch thanthe black ones. 

Keywords:

Crayfish , Astacus leptodactylus eichwaldi , Traps , Catch , Efficiency , Sex ratio , Caspian Sea , Iran