Fin Clips in the Evaluation of Stocking Programs for Muskellunge, Esox masquinongy

Abstract During laboratory and field experiments in Ontario, with hatchery muskellunge 90–235 mm in total length, total removal of a fin did not add to the immediate mortality caused by seining the fish from ponds. The use of an anesthetic during surgery (MS-222) did not affect subsequent survival of marked, stocked fish. Removal of any single paired fin was equally detrimental to short-term (3 months) survival. In contrast, over long periods (10 months) the loss of a pectoral fin was more detrimental than loss of a pelvic fin. Removal of both fins of a pair may cause higher mortality than the removal of one fin. Neither the fin removed nor the anesthetic significantly affected short-term or long-term growth. Within 1 year of marking regeneration of amputated fins was such that recognition of marked fish was difficult and the degree of difficulty increased with time. Estimates based on marked 2-year-old or older individuals could result in substantial underestimates of survival.