Efficacy of the Short-term Saltwater Bath in Purging Crayfish

Abstract

Few crayfish are subjected to commercial depuration systems, whereby animals are maintained in aerated vats without access to feed for 12 to 48 h, due to costs and associated mortality. Therefore, retail customers are often instructed to purge live crayfish in a saltwater bath prior to cooking to reduce digesta in the hindgut. However, the efficacy of this practice has not been substantiated. Thus, this study was initiated to investigate the ability of the short-term hyper-saline bath to reduce offensive contents of the hindgut in crayfish. Trap-harvested crayfish were subjected to four treatments on each of three dates: (1) no washing (controls), (2) 10 minute saltwater bath (19.4 g salt L^-1), (3) 10 minute freshwater bath, and (4) immersion purging for 24 h. Random samples of crayfish were dissected and hindgut contents collected and dried. While the 10 minute water baths reduced the amount of hindgut content somewhat (17 – 26%) and 24 h purging reduced gut contents by about 60% over non-washed individuals, salt in the water bath provided no advantage. Therefore, recommendations for purging crayfish in saltwater prior to cooking are unfounded, although a short-term water bath may have some cleansing advantages.