Sampling to Investigate the Juvenile Distribution of Lake Spawning & River Spawning Klukshu Sockeye

The early and late runs together serve as an indicator stock for international management of Alsek River sockeye salmon, which is linked to Klukshu weir counts. The early run, in particular, is most valued for food fisheries by Champagne & Aishihik First Nations (CAFN) who have concerns regarding recent decline in abundance and potential change in spawning distribution of the early population. CAFN has not been able to harvest the early run in any significant numbers for many years because of conservation concerns, and in several years CAFN even had to close the food fishery, which traditionally targets primarily the early run near the outlet of Klukshu Lake.
Differences in timing, spawning locations, and life history between the two runs are not well understood, and previous work is inconclusive. Fillatre (2002) and Petkovich (2000) document differences between early and late components, but Eggers and Bernard (2011) developed biological escapement goals for total Klukshu sockeye, because (a) they considered the evidence for biologically distinct sub-populations insufficient, and (b) catch could not be separated into early and late components. DFO currently uses a cut-off date of August 15 to track weir counts for early and late components, but Fillatre (2002) showed that the timing of migration pulses varies substantially between years.
The current working hypothesis is that early-migrating Klukshu are mostly river spawners, and that late- migrating Klukshu are mostly lake spawners that also rear in the lake. However, differences in juvenile behavior for these different spawning populations are poorly understood.