Yes, they’re salmon hooks. Per Trey Combs, in Steelhead Fly Fishing, “when a properly dressed wet fly with a turned up eye has been (riffle) hitched and brought under sufficient tension, the head pulls up until it breaks through the surface to create a V-wake.”
Seems like a cool way to get the fish’s attention. Never had the chance to fish this technique, but it sounds like a lot of fun. Although intended for steelhead, it seems like this could be applied for other species. The biggest smallmouth I ever caught came years ago, quite by accident, on a crude deer hair moth I was dragging cross-current.