Is it a coincidence that this year's Sockeye return is much bigger than the other 3 years?
This year's return comes back around the same time as pinks instead a month earlier.
Or perhaps Sockeye are suffering the same fate as rainbow trout - acidic ground runoff in lakes due to de-forestation and pine beetle damage?
No coincidence at all in my mind. Later run Fraser River salmonids will out perform earlier run fish because they encounter less warm water and high flows, but in the early 90's and until recently, these later fish entered the Fraser far earlier than normal and suffered huge mortalities ... Cultus sockeye took a huge hit, as did Weaver Creek, Harrison River and to a lesser extent, the Shuswap component, all mainly due to
Parvicapsula minibicornis, a kidney parasite. The good news is this early entry into freshwater seems to have stopped, that is late run stocks are now returning at near historic dates so hopefully this years Late run fish stay in the salt for as long as they have to, and ... we don't fish the $hit out of them while they stage and then enter the Fraser.
There are others better qualified than I to talk of sockeye nursery lakes limnology and water chemistry ... hope they do.