Study Shows Cutthroats Feed More In Afternoon Than Morning

The cutthroat trout holds the distinction of being the first trout ever documented in writing in the New World. Over 450 years ago as the first European explorers pushed into the present-day United States, at least one chronicler had trout on his mind, perhaps reminiscing of brown trout in his Iberian homeland.

Pedro Castaneda, a member of the 1541 Coronado Expedition wrote while camped along Glorieta Creek near present-day Pecos, N.M., that “Cicuye [Pecos Pueblo] is located in a small valley between snowy mountain ranges and mountains covered with big pines. There is a little stream, which abounds in excellent trout and otters . . . “

Craig Springer

Castaneda wrote about the only trout native to northern New Mexico, Rio Grande cutthroat trout. Another 250 years would pass before Lewis and Clark would make a serious scientific description of westslope cutthroats from Montana, a fish that would eventually be named for science in their honor, Oncorhynchus clarki lewisi.

What’s the most common trout in the U.S.? It’s probably rainbow trout that are the most prevalent. However, that was not always the case. Cutthroat trout could make a strong showing for the widest natural distribution of any North American trout species. Thirteen varieties, or subspecies, of cutthroat trout originally ranged from southeast Alaskan lakes to high-country streams of southern New Mexico. Two subspecies are extinct and the range of many others has been greatly reduced.

Cutthroats Transplanted In The East
By about 1900, cutthroat trout habitat began to degrade from logging, stock grazing, and mining practices. Timbering silted the waters and streams were blocked and diverted for irrigation. Stream banks continue to be trampled by livestock, reducing the cooling effect of stream-side shade. The cutthroat populations responded in-kind and shrunk to present-day levels. But fishable populations exist throughout the West and cutthroat trout have been transplanted back in the East.

This spring, spawning fish take on a beautiful hue of colors unparalleled in the finny tribe. Though the name “cutthroat” was argued as a bad epithet inForest and Stream andAmerican Angler magazines in the 1880s, the name aptly describes the trout’s most prominent feature: a slash of crimson red on the throat. The slash amplifies greatly when fish go on the spawn. The Rio Grande cutthroat, for example, is commonly covered in red from the lower jaw to the tail. The spotting pattern is highly variable among the different subspecies. Some may have only a few large spots around the tail while others may be peppered with dark spots.

A study showed cutthroat trout fed more than three times as much in the afternoon than in the morning.

Cold, clear water is a necessity for this subspecies. Since subspecies in the Rockies don’t migrate long distances, it must have deep pools to survive the cold, high-country winters. The pools are also prime summertime lairs where they lie in wait for food. During the cooler months, the cutts rely a great deal on drifting aquatic insect larvae. But in the summer, terrestrial bugs, such as moths, ants, and grasshoppers, are the main fare. Larger cutthroat trout may eat an occasional chub or a smaller member of their own clan.

Spawning Time Depends On Elevation
Spawning occurs from March to July, depending upon elevation, when water temperature reaches about 45 degrees. Male fish mature at 2 years old and females at 3, either sex being about 7 inches long. Females lay between 200- and 4,500 eggs in redds built over clean, pea-sized gravel riffles where oxygen-rich water percolates over the developing fish. Females only become ripe every other year. The eggs hatch in several weeks and are about 2-1/2 inches long by the following spring. Cutthroat trout commonly spend their entire lives within 250 yards of their birthplace.

Growth is slow in the high country. By their fifth year, this fish may have reached 16 inches long; and rarely does it live beyond seven years. Recent diet studies show that their feeding, not surprisingly, slows way down in the winter months. In warmer months though, studies that followed individual fish in the wild revealed an interesting life style.

Nine Wyoming cutthroat trout were implanted with radio transmitters and followed from mid-July to late August. To get a complete picture of what the trout were doing around the clock, each fish was individually monitored for at least one minute in every hour, over a 24-hour period. Biologists noted fish behavior, such as feeding or loafing.

Instead of remaining at feeding stations throughout the day, trout in this study moved an average of 275 feet per day in July. But as the season progressed they tended to move less — by late August they only moved about 85 feet per day. Regardless of distance traveled, many of the trout were found back in nearly the same place every morning.

They Feed 15-to 19 Hours Daily
The cutthroats fed 15- to 19 hours each day with only 40 percent of the fish feeding after dark. Ninety percent of fish fed at dusk and dawn, but in daylight all fish were observed feeding.

To determine their favored fare, biologists flushed out the stomach contents of 36 cutthroats. Over the course of the study, half were flushed between 7:30 a.m. and 11:30 a.m., and the other half between 4:30 p.m. and 6:30 p.m. The contents were separated into aquatic and terrestrial insects.

Cutthroats consistently ate more aquatic insects than terrestrials. Nearly 60 percent of their diet was composed of the larval and adult forms of aquatic bugs, with caddis and mayflies dominating. Dry fly fishermen may be pleased to know that terrestrial insects, such as moths and tiny beetles, made up 31 percent of the diet. Based on stomach flushes, trout fed more than three times as much in the afternoon than in the morning.

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When not penning stories about the outdoors, Craig works in communications for the U.S. Fish and Wildlife Service. His work has appeared in Flyfisher, Outdoor Life, ESPN Outdoors, and the New York Times. He holds degrees in fisheries and wildlife management from Hocking College and New Mexico State University, and earned an M.S. in fisheries at the University of Arizona, researching smallmouth bass. He earned an M.A. in English at the Univeristy of New Mexico where he studied rhetoric, and learned to read books with hard covers. He writes weekly for


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