Cambaroides ( Asian crayfish )

The contribution below is from Shiro Nisimura and Masanobu Hirata in Japan . Thank-you Shiro and Masanobu.

   


The Japanese crayfish

Cambaroides japonicus 

Please bear with us as we sort out a few things, unfortunately we have some language barriers to cross but i'm sure we will finally get there.

   

Text and photographs by Hyun Sook Ko


The Korean crayfish

Cambaroides similis:

Color is brown.Maximum carapace lengths of female and male crayfishes are approximately 3 and 4 cm, respectively. Habitat is limited small streams which are surrounded by trees and a large quantity of fallen leaves in mountain. Water is very clear. BOD is under 1 ppm, DO is over 7.9 ppm, pH is 6.4-6.7, turbity is about 0.4-1 NTU. Water temperature of stream is usually 7 degree during spring, 16 degree during summer, and 13 degree during autumn. Stream is frozen from December to March.


Aquatic animals are instars of Ephemeroptera and Trichoptera, Turbellaria, and water striders. Green algae and Diatoms attach to stones. Breeding season ( the occurrence of ovigerous females) extends from May to June (water temperature:11-14 degrees). Egg number is ranged from 48 to 62 and carapace length of females is from 18.2 mm to 22.7 mm. Eggs are attached to mother's pleopod for 3.6 weeks. After hatching, juveniles (juvenile stage 1 and 2) are also attached to mother's pleopod by means of their curved pereiopods for 6 weeks. From juvenile stage 3, they leave their mother. They are intermediate hosts of lung flukes.
Recently, abundance of Korean crayfish has been declined, probably as a result of environmental changes and water pollutions. Moreover, it is confirmed that the red swamp crawfish, Procambarus clarkii, has been introduced in Korea. At present, the population protection of this species is needed in Korea.