Three friends and I fished the Brooks River in Alaska for Sockeye just last June. I was very interested in this exact topic. A guy who wrote a widely published book, I think it's Fishing Alaska, was of the firm opinion that Sockeye took the fly. He describes the takes he has observed as very, very subtle. Silver Hilton was good enough to lend me some help via e-mail.

We fly-fished and I'd say it was about 50-50 hooks from the outside in and hooks on the insides of the mouths of the fish we caught.

Most of the staff guides seemed of the opinion that getting the fly to the right depth was the most, or only, important aspect and that it was a "lining" deal. Since every fly we threw at them worked once it was gotten to the right depth, either the Sockeye were just ravenous, which I keep reading they're not, or the flies were simply floating into their mouths or being lined into the side of their mouths. I have a sneaking suspicion that "lining" was the most likely answer, but I would bet that some of those fish did take voluntarily, based simply on the locations of the hooks inside the mouths.

I never saw a Sockeye move to take my fly, there were just too many of them (and they weren't snugged up to the the riverbank) to discern which one was doing what relative to my fly. And they all seemed to be opening and closing their mouths all the time.

My experience supports the conventional wisdom that a small, sparse fly worked much better than a larger or more fully dressed fly. Small brassies and sockeye johns were my favorites. My friend had the best luck of all of us on a martin river smolt.

Pound for pound, I'd have to say they were spectacular fish to catch. They had no quit in them and they'd fight and jump and run and fight until you got them by the tail or dragged them onto the bank.