A few years ago, during coho season I caught three adipose clipped cultus sockeye during the fall salmon season. Two of them were a bout a km above the Sweltzer creek, but the third was a few km above Tamahi. I was surprised to find it that far up, but have heard similar stories from other anglers as well. Whether they drop back down or not, I would also be curious to know.
A few years ago ,I got one mid-October above Tamihi too.