Inconnu, Stenodus leucichthys, Migration Studies in Alaska 1961–74

Abstract

During studies on inconnu, Stenodus leucichthys, in the Kobuk, Yukon, Koyukuk, Kuskokwim, Holitna, and Chatanika rivers, and the Selawik and Minto Flats areas, 3907 fish were marked. Nine hundred and ten (23.3%) had been recovered by December 31, 1974.Tag return data indicate that tagged inconnu comprise four major populations: Kobuk–Selawik, lower Yukon, Kuskokwim, and Minto Flats.Inconnu undertake rapid downstream postspawning migrations to wintering areas in lower reaches of large rivers (Yukon, Kuskokwim) or slightly brackish inlets (Hotham Inlet, Selawik Lake), then begin slow upstream migration before spring ice breakup, with nonspawning fish travelling to summer feeding areas and spawners migrating to spawning grounds during summer and fall. Minto Flats fish are nonanadromous.Three fish, tagged in the lower Yukon River and recaptured in the Koyukuk River, migrated upstream 1035–1156 km, averaging 13.8 km/day. The longest migration recorded was nearly 1,600 km.