Is the Presence of Broad Whitefish in an Upland Lake an Indication of a Lake Resident Life History Form? Alaska Fisheries Data Series Number 2020-4

Broad Whitefish Coregonus nasus is a large species in the subfamily Coregoninae. It occurs in a number of Arctic and subarctic rivers in North America and Asia. The species spawns in October or November. Juveniles emerge the following spring and are transported downstream with high flows to rear in estuaries and floodplain lakes for a few years until maturity is attained. Mature fish then migrate back upstream to their natal origins to spawn. Post-spawning individuals typically overwinter in large river environments or estuaries and migrate into floodplain lakes during summer to feed. In the 1970s two different fisheries biologists captured Broad Whitefish in Whitefish Lake, a large upland lake in the headwaters of the Hoholitna River, a tributary of the Kuskokwim River in western Alaska. It is very unusual for the species to occupy upland lakes so its occurrence there could potentially represent an undescribed lake resident life history form. We conducted a 3-day sampling program in Whitefish Lake in late August, 2012, to determine if Broad Whitefish were present in the lake in late summer, and if so, whether individuals were preparing to spawn or not. We captured six species in the lake but no Broad Whitefish were captured or observed. We conclude that the species occupies Whitefish Lake during early summer to feed, similar to its seasonal pattern with floodplain lakes, and therefore, its presence does not represent a lake resident life history form.