Colorado South Platte Greenback Cutthroat Trout Restoration

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In July, Colorado Parks and Wildlife (CPW) aquatic biologists and volunteers carried 10-pound bags of rare greenback cutthroat trout up steep terrain in an effort to re-establish the fish in alpine streams of the South Platte River drainage. Trout Unlimited and other nonprofit conservation organizations provided volunteers to assist in the restocking.

CPW biologists hope the fish, each a year old and about 4 inches long, will thrive and continue the long process of restoring the native greenback in its historic habitat  and remove it from the U.S. Fish and Wildlife Service’s list of threatened species.

Since discovering in 2012 the pure greenback population in a tiny ribbon of water known as Bear Creek on the southwest edge of Colorado Springs in the Arkansas River drainage, CPW staff has mounted a massive effort to walk Bear Creek, collect and spawn the fish each spring, rear them in hatcheries, and stock them in a reservoir and two streams that the agency cleansed of other non-native fish to create the best conditions possible for their survival.

Despite all that work, the first stocking effort of 4,000 tiny, one-inch greenbacks on Herman Gulch and Dry Gulch last September was somewhat disappointing. A recent survey of the streams found no survivors. As a result, CPW decided to restock July 17 with 960 older, more robust greenbacks.

The earlier release date also was designed to give the fish more time to acclimate and grow before winter. What CPW researchers know is that it takes approximately 3 years to restock and establish fish in a stream.

Presiding over the restocking effort were Boyd Wright, CPW’s Northeast Region aquatic conservation biologist and Paul Winkle, area aquatic biologist. Also assisting was Harry Crockett, CPW’s native aquatic species coordinator and chairman of the multi-agency Greenback Cutthroat Trout Recovery Team.

“This is a really big deal,” Crockett said of the effort that saw dozens of volunteers serve as fish Sherpas hauling bags up fish up four miles of steep terrain to find ideal spots along Herman Gulch where the greenbacks might take residence. “We need to get these fish in here and see them survive.”

To prepare the streams as greenback incubator sites, CPW staff in 2015 walked each, mile by mile, electroshocking about 600 hybrid cutthroat and carrying them out for relocation in Clear Creek. The streams were chemically cleansed of other species so baby greenbacks might thrive.

Then came the stocking of tiny greenbacks last September, the survey for survivors last week and finally the second restocking July 17. Though greenbacks stocked into Zimmerman Lake west of Fort Collins are thriving, biologists want to see them restored in their more typical habitat: cold, clear, alpine streams.

The long-term goal is to have greenbacks populating a network of streams like Herman, Dry Gulch and Clear Creek, for example, throughout the South Platte drainage. But for now, CPW biologists have to get them to survive a winter.

The survey and stocking efforts will be repeated next year and biologists will be able to track the cutthroats by scanning them with a wand to read identifying tags inserted in each fish.

The greenback cutthroat trout is the official state fish of Colorado.

Colorado Parks and Wildlife

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