METHODS FOR NONLETHAL GILL BIOPSY AND MEASUREMENT OF NA-ATPASE ACTIVITY(, K+ )

A gill biopsy, in which a small portion of gill tissue was removed fro m anesthetized fish, was shown to have no detrimental effect on subseq uent survival, growth, and salinity tolerance of juvenile Atlantic sal mon (Salmo salar). A method for measurement of Na+, K+-ATPase activity in this small amount of gill tissue is presented. These methods are u seful for nonlethal monitoring of physiological smolt characteristics in salmonids and may have applications in the study of disease, toxico logy, and physiological ecology of many fish species.