The Imperiled Cutthroat by Greg French

Author:Greg French
Language: eng
Format: epub
Tags: Fly Fishing
ISBN: 9781938340581
Publisher: Patagonia
Published: 2016-08-19T16:00:00+00:00

If mackinaw populations are so vulnerable, why, I wonder, isn’t the suppression program working in Yellowstone Lake?

In About Trout, Behnke contradicted the idea that the lake’s native cutthroats and nonnative mackinaw always utilize separate microhabitats. Apparently young cutthroats of less than twelve inches are rarely found in Yellowstone Lake, and Behnke speculated that once the tiny hatchlings have migrated from their redds in the spawning rivers, they probably spend time deep down in the open water well offshore. He also noted that fingerling cutthroat trout are not found in the guts of adult cutthroat trout (even though big cutthroats are cannibalistic, being famous for gorging on accumulations of fry at the river mouths), and that cutthroat trout do not move into the shoreline shallows until the third or fourth year of life.

Because Yellowstone Lake is nutrient-poor and often iced over, there is a scarcity of food. Poor nourishment affects egg production, and consequently mature cutthroats only spawn every second year. Despite the fact that Yellowstone Lake’s cutthroat trout eat plenty of insects, especially in summer, the bulk of their diet comprises crustaceans, primarily planktonic daphnia (water fleas), and bottom-dwelling amphipods (scud).

(The relationship between feeding seasons and trout fertility explains why trout have failed to establish viable populations in many alpine waters throughout North America. Usually it’s not because the lakes freeze to the bottom or that waterweeds suck oxygen out of the water during ice-over, as is commonly assumed, but because the fish never mature.)

Now, ever since I saw my first mackinaw at Lake Pearson I have wanted to catch one on a fly. Before leaving Tasmania, I even considered hiring a local Yellowstone outfitter to take me out on the lake. But since the mackinaw live deep down and I would have no opportunity for stalking my prey, I quickly lost interest. Why blind-fish for introduced mackinaw when I could be polaroiding natives?

I wonder why catching native fish in native environments is so important to me. After all, brown trout aren’t native to Tasmania, and I still consider the fishing at home to be equal to the best in the world. Perhaps I like Tasmanian browns because we have no native sportfish. Perhaps it’s because these days our brown trout are more genetically diverse and wilder that most brown trout in Europe. If that sounds like rationality being trumped by fervor, I suspect you are right but, hey, we’re all filled with contradictions. Take Dale, a vegan friend of mine who won’t eat honey because he doesn’t like upsetting insects. I once tramped with him up a backcountry stream on the South Island of New Zealand, and I swear he swatted a million sand flies.

Currently Dale is in Yellowstone Park working out ways to kill nonnative trout. Before leaving home, I wanted to know if the stomach contents of harvested mackinaw were being systematically examined by scientists working on the mackinaw-suppression program. More specifically, I wanted to know whether anyone knew if the consumption of cutthroat trout by mackinaw was reducing over time, and if so, what alternative food might be filling the void.

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