Mastering the Morrish Mouse
June 30, 2011
Help me, Minnie! Help!" guide Tom Provost squeaked in his mock Mickey Mouse voice. "I've fallen in the river and I can't get out."
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.
"I never cleaned a rainbow trout in Kamchatka that didn't have at least one mouse in its stomach," Blair said. Many rainbow stomachs contained more than one mouse.
In Alaska I've always released all my trout, but some fish have oddly large lumps in their bellies — too
irregular to be salmon eggs or any other small food sources.
Blair doesn't fish a mouse pattern with a steady rod like a steelheader. He uses the rod tip to twitch and chug the pattern across the river as if he's fishing a bass popper, and he does it with deadly effect. He says he gets more strikes on the pause doing it this way, and more consistent hookups since the trout are hitting a momentarily stationary target.
On Headwaters Creek (an unnamed stream at the headwaters of the Nak-nek River) Provost showed me how he casts into backeddies behind midstream rocks, into the slow water on the opposite shore, or throws a downstream mend in his line to keep the mouse swimming downstream as much as possible.
"I don't think too many mice can or would swim upstream or straight across," he said. "They can swim alright, but not that good."
I used to think mousing was an oddity even in Alaska — used only during rare events such as lemming migrations or localized population explosions — but that's not the case. Trout eat mice almost everywhere in the Bristol Bay region, provided there is suitable nearby habitat. And they eat mice all summer. Several guides have told me about catching preseason trout on mice patterns in early June before the first guests of the season arrive and while there is still ice on the higher-elevation lakes. As the season progresses, the mousing only gets better as the water levels drop, the water temperature rises, and the trout get more aggressive in general as their metabolism increases.
The best mousing season in Alaska may be in August when the sockeye spawning migration increases rainbow trout populations in small, mousy tundra streams. In the afternoon, water temperatures often rise into the mid-50s, and the trout put the feedbag on. Even in places where the sockeye are clearly spawning, and the trout are gathered in the riffles to eat eggs, they jump all over mouse patterns.
The best mousing waters are the shallow bubbling riffles between the major pools. Pay special attention to the shallow riffles just below the pool tailouts, where the salmon may be starting to dig their redds. Back home I'd walk right past these areas, but in Alaska the food source (salmon eggs) frequently keeps the trout in skinny water.
My favorite pattern is the Morrish Mouse, but other foam-backed patterns such as the Mr. Hanky and Cheeky Mouse are also easy to swim in the surface film due to the shape of the flared foam. Like the tip of a water ski, the foam doesn't just float the fly, it pushes water and swims the fly.
Old-fashioned all-hair type patterns are less effective. They either bury themselves underwater (their faces are shaped similar to a Dahlberg Diver) or else they skim too highly across the surface. A real mouse swims in the surface with a great deal of its body underneath.
Blair recommends a short, heavy leader for mousing, both to turn the fly over, and to quickly bring the trout to hand. A 6- to 8-foot 0X leader is right for casting toward sod banks, fallen logs, alders, and other obstructions along the shore. There is nothing delicate about this fishing and a heavy tippet will save you from losing a half-dozen expensive or time-consuming mouse patterns per day.
To cast large mouse patterns most efficiently use an 8-weight rod, but on a small stream 30 to 50 feet across, an 8-weight feels like overkill, and it's easy to cast bank-to-bank and make snappy mends with a 9-foot 6- or 7-weight.
Mousing the World
While Alaska might be North America's best mousing venue, these patterns work anywhere trout and mice, lemmings, and voles intersect.
The broad-shouldered brook trout of Labrador are famous for taking waking mice patterns. In the summer of 2009, coyote populations were down in the Yellowstone ecosystem, and riverbank mouse populations were up, with reports of good mousing on the Madison, Yellowstone, and other local rivers.
In Pennsylvania, I heard fly shop talk this summer of a 24-inch brown trout from Penns Creek caught on a mouse (at midday no less) and in New Zealand, there are boom and bust mouse cycles directly related to the availability of beech tree seeds. When the seeds are at the top of their cycle, the trout gain pounds of weight from feeding on swimming mice. Once in a Blue Moon (On the Fly Productions, onthefly.co.nz) is a movie about this once-per-decade "mouse year" in New Zealand.
My best mouse story is about a fish I didn't catch. On a recent visit to Steamboat, Colorado, I attempted to convert my companions into the cult of the mouse with a moonlit jaunt down to the Yampa River. Four guys (two on each side of the river) planned to make just one steelhead-style pass down a single pool to see what we could turn up using only the Morrish Mouse.
We heard a lot of sloshing around out there in the dark, and rightly assumed we missed quite a few fish, but we hooked five trout solidly and landed three browns in less than an hour of fishing. Steve Hoffman's 27-inch brown consumed the Morrish Mouse in a toilet-size flush that left little doubt in our minds about the global effectiveness of mouse patterns.
Ross Purnell is editor of Fly Fisherman.