PHYSIOLOGICAL ADAPTATIONS OF FRESH-WATER CRAYFISHES THAT PERMIT SUCCESSFUL AQUACULTURAL ENTERPRISES

There are over 400 species and three families of freshwater crayfishes . Many species are collected for food and/or fish bait but fewer than ten are commercially cultivated. We discuss the physiological adaptati ons that permit these species to be successfully cultivated. The most important cultured species include: Northern Hemisphere-Cambaridae-Orc onectes immunis, Procambarus clarkii, and Procambarus zonangulus, and Southern Hemisphere-Parastacidae-Cherax destructor. Procambarus clarki i is, by far, the most important species and has been successfully int roduced to all continents, save Antarctica and Australia, from its nat ive North America. All species may be cultivated entirely in closed, i ntensive systems; however, economics are such that they are commercial ly produced, for the most part, by establishing perpetuating populatio ns in earthen pond systems. All species tolerate low oxygen, adapt wel l to aerial exposure, and persist for extended periods in burrow syste ms in the absence of surface waters. The cultured species have high fe cundities, rapid growth rates, and mature quickly. Aquaculture of fres hwater crayfish is in its infancy. Therefore, it is likely that additi onal species with favorable adaptations discussed here will be identif ied for cultural purposes.