The Relative Growth of Different Organs And Length – Weight Relationship In Freshwater Crayfish, Astacus Leptodactylus

ZAHMATKESH Asgar¹ , KARIMZADEH Katayoon ², RAHMATI Hamid Reza¹

¹ Mirza Koochak Khan Higher Education Center for Fishery Science and Technology, Rasht , Iran

² Marine biology department, Azad university branch of Lahijan, 1616, Lahijan, Iran

 ABSTRACT

The crayfish (Astacus leptoductylus ) are distributed in south coast of Caspian  Sea, Anzali lagoon, some rivers and water reservoirs in Iran, Estimation of weight ratios in various organs and determination of length – weight relationship in Astacus leptoductylus could used , in order to provide information for proper harvesting weight and protecting its stocks in natural water resources. In this study , about 10000 juveniles crayfish with approximate weights 200mg were stocked in earthen ponds. Numbers of crayfish with differences ages , 1 month (<1g W ) , 3 month ( 1-5 g) , 16 month ( 5-20g) were captured. The weights of various organs of crayfish in respect to sex were measured. There were no significantly differences between the weight proportions of them in male and females . The average weight in abdominal muscle of female
(16.6%) was higher than that of male (16%) , while average weight in chelipeds of male ( 13.5%) was higher than that of female ( 12.7%) . Data shown that different organs i.e. abdominal muscle, visceral , claws, carapace, abdomen shed and tail include 16.5% , 49.7% , 13% , 10% , 5% and 3.5% of the whole body of A.leptoductylus respectively .Results revealed that there was an exponentional relationship between total length and total weight , and among these parameters with other portions of the animal body . With increase at age weight increment improved , but length increment rate reduced. However, the results obtained of this study may enable us to evaluate net muscle and edible portions or crayfish body.

 KEYWORDS: Crayfish , Astacus leptodactylus , growth , body length , body weight.