| Abstrakt: |
In northwestern Canada, Inconnu, Stenodus leucichthys nelma, is at the far eastern part of its partially circumpolar range. Within the Mackenzie River system of Canada there are a number of distinct populations of Inconnu. There is strong evidence for distinctive life history type based on genetics and migratory patterns, however, the factors controlling the population dynamics of Inconnu remain unclear. There is evidence that vulnerability of Inconnu populations is a function of the life history type, habitat quality and fisheries. Inconnu have not done well where there are commercial fisheries such as in Great Slave Lake but support a substantial subsistence harvest at tributaries of the lower Mackenzie River, such as the Arctic Red River and the Peel River. On the other hand Inconnu population fluctuations in the Yellowknife River have occurred independently of fishing pressure, and may instead be connected to habitat degradation and recovery. These findings are similar to parallel studies in Eurasia that show Inconnu populations have declined or become extirpated through habitat losses from hydro-electric dams and fishing. We note there are substantial differences in age and size structure of different life history types which likely influence productivity and vulnerability. Much of the biology such as juvenile life history, ontogenetic shifts in diet, reproductive requirements and over-wintering ecology of this species remains poorly understood. |
