What else is new?

[Steve]

Who needs fish, anyway?

[Midway Tommy D]

I've always found it fascinating, and also quite intriguing, that itchyologists, biologists & scientists seem so alarmed and confused when an implanted non-native species starts struggling and their population begins to decline. I often wonder if they take into consideration why there wasn't a natural population in existence prior to their introduction, in Montana's rainbow and brown trout case, prior to 1890? Hmmm?

[Steve]

As widely adaptable species, these transplanted trout were doing fine for over a century. Their population declines are correlated with substantial, relatively rapid changes in water quality, temperature, oxygenation, and other factors, which affect not only the fish, but their food sources. Indigenous populations are not guaranteed adaptability to rapid environmental changes.

[Paul Roberts]

I found it a bit shocking that the trout streams I got to know in CO were different from streams in the East, in that the CO streams got smaller in volume as you traveled downstream. Whereas eastern streams got larger as you moved down the watershed. To find large trout in those eastern streams, I'd work down into larger volume water that could maintain appropriate temperatures. This varied by watershed due to groundwater, canopy (shade), and year to year due to drought and summer air temps. Some of my early fisheries work was assessment of "marginal" trout waters in NYS, the results of which would classify, or re-classify, trout stream quality.

I soon learned that my CO streams got smaller as I went down the watersheds bc they were drawn off by miles of ditches that fed the State's agriculture. Agriculture, lawns, and the eastern broadleaf trees that line the streets of Front Range towns, are all built on arid short grass prairie, and rely on miles of ditches and hundreds of small reservoirs, that in turn rely on snowpack. "Where's the snowpack at?" is a constant question.

Drought is scary in the West. "Droughts suck the life out of the land and everything that lives on it", is how I came to put it. The drying up of the West is a scary pattern. A friend of mine, an affiliate of the Natural Science Museum in Denver, would invite me along on excursions into the high country to visit the disappearing snowfields and edges of glaciers to look for artifacts, on land that hasn't been exposed to that 'big sky' in 10,000 or more years. Exciting, weird, and... scary.

[Midway Tommy D]

Paul, your experience sort of lays some groundwork for why certain species of trout weren't considered to be native to areas of the mountains and foothills in the first place. A good portion of CO, WY & MT are pretty arid at times, and treeless & grassy, especially in their eastern portions. NE has a heck of a time, and has for decades, maintaining a decent stream trout population. About the only place they actually do well is in Lake Ogallala, which made up of cold water coming out of Lake McConaughey through Kingsley Dam. If one really thinks about it, a hundred years or so, is pretty short term when compared to earth's actual existence.

[Paul Roberts]

Yes, the native "trout" on the E side of the rockies in CO was the Greenback Cutthroat. They were pushed to near extinction with pressure from invasive salmonids of all types. All coldwater species there, invasive or not, rely on either altitude or snowpack, usually both. The plains are not conducive to coldwater species. The western slope mountains, away from the high peaks, are at risk to arid conditions. I guess the question at hand is whether coldwater populations in the west, as we know them, will survive current drought conditions.

There is evidence that drought played major roles prehistorically in the success -and sheer existence- of cottonwood trees on the plains. Apparently, drought periods killed off all cottonwoods, only to have them recolonize up the river channels during periods with adequate moisture. Fish species diversity in the plains rivers is uniquely low, apparently due to the same reason: drought. This see-saw battle has been being waged for millennia. The question is, are current drought conditions exacerbated by human impact on climate. "Trout" are but one canary.