Although my Morrish Mouse swimming through the riffles didn't have ears, nose, and whiskers on top like some of the fancier patterns out there, I imagined its bulky hair body and tantalizing tail looked like the real deal from below—with or without the ventriloquism from my guide. The key is not how realistic the pattern looks; instead, it's the low-riding, sputtering swimming action as the mouse furrows its way through the riffle that incites trout to commit violence against rodents.
Sometimes the trout "blow up" on the mouse, acting as though they don't merely want to eat it—they want to maul and abuse it. Other times it's more like a shark attack, with the trout creating its own V-wake behind the mouse, closing the distance in a calculated, predatory fashion. These aggressive strikes, while exciting, more often than not result in a limp line.
Whether the mouse is built right on the shank like the Morrish Mouse, or it has a trailing stinger hook like Mr. Hanky or similar patterns, you'll have to get used to seemingly crushing attacks that just don't connect. It could be the trout are employing a smash-and-grab tactic, trying first to drown and/or disorient the mouse with the idea of actually eating it once it's underwater. I've seen many trout do exactly this in clear water, first hitting the fly, then circling around below looking for their meal.
The best hookups often come from more subtle takes, and the Alaska guides I've spoken to confirm this. When all you see is a white maw opening up behind the mouse, you know the trout is serious about eating in one pass.
Just as in skating surface flies for steelhead or Atlantic salmon, you wait to set the hook, allowing the fish to take the fly and turn back to its holding position. Often, the trout hooks itself in this process, drawing the hook to the corner of its mouth. For good measure—once the trout clearly has consumed the fly—sweep the rod to the side to firmly bury the hook. But you should never "set" the hook visually as you would when fishing a dry fly; you risk pulling the fly away too soon.
I fish a mouse pattern the same way as a skating steelhead fly by casting across-stream, pointing the rod tip downstream, and allowing the current to work the fly back across-stream. In slower water, cast straight across at a 90-degree angle. In faster water, angle your casts downstream at a 45-degree angle so the fly doesn't race too quickly. Mice can swim, but they aren't Michael Phelps.
Of course, this begs the question of whether the trout actually perceive their target as a mouse, or whether the movement simply triggers an instinctual strike.
"There's no doubt they think it's a mouse," Will Blair told me during a day of mousing on Nanuktuk Creek (the Little Ku) in Katmai National Park. Blair is the booking agent for Rapids Camp Lodge, but he spent a decade of summers managing wilderness camps and exploratory expeditions in Kamchatka, where the terrain, climate, and topography are similar to Alaska. On exploratory float trips, Blair often ate rainbow trout.
Fly Tying The Morrish Mouse
HOOK: #4 Tiemco 5263.
THREAD: Black 3/0.
TAIL: Brown rabbit strip trimmed to end tuft.
BACK: Black closed-cell foam trimmed into a long taper at the rear.
BODY: Spun dark cow elk or suitable alternative hair, trimmed.
Morrish Mouse Step 1 of 6
Attach the thread to the rear of the hook. Tie in the rabbit-strip tail, and then add the narrow end of the trimmed foam.
Morrish Mouse Step 2 of 6
Hand stack the elk hair, and clean and trim the butts. Tie in the hair with the tips toward the back. Flare the hair and spin it tightly. Repeat this process with four to six more bunches.
Morrish Mouse Step 3 of 6
Comb and press the hair out to the sides, and part the hair along the top of the hook shank. Use scissors to trim along the top to clear a platform for the foam back.
Morrish Mouse Step 4 of 6
Pull the foam forward and tie it down at the head of the fly. Whip-finish in front of the foam. Trim the foam, leaving roughly 1/3" facing forward for the skating lip. Comb the hair out to the sides.
Morrish Mouse Step 5 of 6
Use a double-edge razor blade to trim and flatten the elk hair from the belly of the fly.
Morrish Mouse Step 6 of 6
Note: Morrish opposes the use of stinger-style hooks for trout fishing. The narrow gap on this pattern is by design, and will greatly reduce mortality. Please only fish this pattern barbless.