The Stream Doctor

July 21st, 2003

Email YOUR Questions directly to the Stream Doctor. This is your opportunity to get an experts professional opinion on anything stream related.


Q. In an earlier response you said that the cutthroats of the Buffalo Ford [Yellowstone National Park] area are caught an average of six times a season. What effects on their population and breeding are caused by this?

A. I have an update on the numbers I gave earlier. The publication Yellowstone Science has an interesting series (this is Part II) entitled "A Grand Experiment" that discusses the history of fishery management in Yellowstone. In this recent article, the author states, "By the 1980s, cutthroat between Yellowstone Lake and Sulphur Caldron on the Yellowstone River were caught an estimated average of 9.7 times during the 108-day catch-and-release season, many of them two or three times in a single day." The author also states, "The very characteristics that made the cutthroat so popular as a sportfish--its abundance and vulnerability to angling--may also have imperiled it."

The author does not discuss specific aspects of the impact of catching these fish so many times on their population and breeding, but reading between the lines, it surely indicates that such pressure must contribute to some population impact. Cessation of egg collection and fish stocking in the 1950s did not relieve the constantly increasing fishing pressure, so it appears that this kind of pressure adversely impacts the population. Even in a catch-and-release fishery, a certain percentage of fish will be lost to hooking mortality. However, it also appears that the very fact that there are still so many fish to be caught, even if many are repeaters, that the overall population must be reasonably healthy. I do not know if reproductive rate has changed materially; again, there seem to be a lot of fish in that reach. It also looks like the newly found problem with lake trout in Yellowstone Lake may have a more severe impact on the cutthroat population over time than does the current fishing pressure.

The above response, gleaned mostly from uncertain assumptions, seemed a it weak, so I called one of the fishery biologists in Yellowstone to pursue your question. First, he said that the study which determined the 9.7 number and the two or three times per day was not very rigorous in terms of real scientific control. So, I'd take them with a grain of salt. What he did say, that was more applicable to your original question, is that they have better evidence to show that disturbance of trout redds by wading fishermen probably have a greater detrimental impact on the reproductive capacity than does the repeated catching of the trout.
~ C. E. (Bert) Cushing, aka Streamdoctor
105 W. Cherokee Dr.
Estes Park, CO 80517
Phone: 970-577-1584
Email: streamdoctor@aol.com

The 'Stream Doctor' is a retired professional stream ecologist and author, now living in the West and spending way too much time fly-fishing. You are invited to submit questions relating to anything stream related directly to him for use in this Q & A Feature at streamdoctor@aol.com.


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