Home Forums Hunting & Shooting General Big Game Yellowstone Cutthroat Trout, Grizzlies and Predation on Elk Calves

Grizzlies may be link between drops in cutthroat trout and elk calves

By CHRISTINE PETERSON Star-Tribune staff writer

A drop in migratory elk calf numbers in and around Yellowstone National Park may be linked to a loss of cutthroat trout in Yellowstone Lake, according to research published Tuesday.

Grizzly bears may be the link.

As cutthroat trout numbers declined, some grizzly bears began switching from eating trout to preying more on elk calves, said researcher Arthur Middleton.

Middleton was the lead author on a paper called �Grizzly bear predation links the loss of native trout to the demography of migratory elk in Yellowstone,� which was published in a science journal called Proceedings of the Royal Society B.

�We perhaps shouldn�t be so quick to departmentalize fisheries management and wildlife management because even though they seem like separate parts of an ecosystem they can turn out to be more closely linked that we thought,� Middleton said.

Drought still plays a role in declining elk calf production by reducing pregnancy rates, and increasing numbers of bears and wolves are also a factor. However, research suggests some bears are eating more elk calves while elk are still on their summer range near Yellowstone Lake, said Middleton, who worked with nearly a dozen other biologists on the paper.

Middleton used several research papers about grizzly bears and cutthroat trout as well as grizzly bears and elk calf predation to draw his conclusions. He worked on the paper while finishing his doctorate at the University of Wyoming and is now with the Yale School of Forestry and Environmental Studies.

Elk calf ratios in migratory herds around the park have decreased in varying degrees since the mid-1990s, and have been low since 2002, said Doug McWhirter, Cody district wildlife biologist for the Wyoming Game and Fish Department.

�This is one piece that could explain why the increase in elk predation is occurring,� McWhirter said. He was also a co-author on the paper and worked with Middleton on elk monitoring.

The increased predation has not decimated elk herds around Cody. All are still at or above population objectives. However, wildlife officials have limited hunting. Licenses dropped nearly 75 percent from 2002 to 2012 for elk in the Sunlight Basin and Crandall areas, he said.

The loss of cutthroat trout is not hurting grizzly bear populations, said Mark Bruscino, large-carnivore section supervisor for Game and Fish. Trends show increasing numbers and densities of bears in the greater Yellowstone ecosystem. Grizzly bears are opportunistic, which means if cutthroat trout aren�t around, they�ll eat something else.

In some cases, that other food may be elk calves, Middleton said.

Grizzly bears historically fed on some of the millions of cutthroat trout that moved up tributaries of Yellowstone Lake to spawn.

Problems started in the early 1990s when lake trout were discovered in Yellowstone Lake. An aggressive, nonnative fish, lake trout eat cutthroat trout but spawn deep in the lake bottom, which means they are rarely accessible to predators such as grizzly bears. Cutthroat trout numbers have declined up to 90 percent since the introduction of lake trout, Middleton said.

Yellowstone National Park officials have been fighting the lake trout invasion. They removed more than 300,000 lake trout in 2012, levels high enough to start suppressing the lake trout population, according to a release from Yellowstone National Park.

If cutthroat populations return close to their historic levels, it is possible some bears could begin eating trout again, Middleton said.

Funny how grizzlies started eating more elk about the same time wolves were introduced and started to breed.

It's been a perfect storm against elk. Overpopulation, then drought, wolves, and bears. Too bad test and slaughter didn't pass...

Interesting study though, I wonder how much impact the collapse of the cutthroat and focus on elk has helped or slowed their increase in overall numbers.

Mudhen: You apparently don't care enough about that article to include your opinion/feelins/experiences regarding it in your posting?
Well I care.
Its an absolute load of green-assed bullshittery!
Nothing more - nothing less.
Idiocy is rampant anymore it seems.
Sheesh.
Hold into the wind
VarmintGuy

Why? How is it bullshit?

Google "yellowstone cutthroat grizzly bears"

There's metric [bleep] ton of info about there about the fishery collapse and the study of the impact on the bears. Look at some of the whitebark pine nuts data too. The bears have simply adapted

�There is one stream that feeds Yellowstone Lake and in the past it had over 70,000 spawning cutthroat trout � now there are only 500,� said Fortin.

This is just a compounding factor, wolves do most of their killing in the winter and now bears are compounding risk in the summer....like I said, it's been a perfect storm.

I appreciate that mudhen passes along the info without feeling the need to weigh in. Far too much loose opinion around already, and a serious dearth of facts, and well reasoned conclusions.

Don't attack the messenger if you don't like the message.

As you regularly display.

Net read ...Thanks MH.

another article stated a griz will eat 1 elk calf per 3-5 days.
I watched 5 wolves kill 19 elk calves in 25 minutes in the upper Lamar.
For the rest of the day while I watched, none were eaten.

Who's the problem?
What a bunch of CRAP!!

I post things that I think that some here will find interesting. One in a while, someone will post a question that I can answer based on what I have learned over the years. FWIW, I don't have a firm opinion like you because I have not seen the peer-reviewed articles. I have had enough experience with journalists to know that the "angle" of a story is usually more important to them than the facts.

The article above raised some interesting questions and recalls an oft-repeated quote attributed to Frank Egler: �Ecosystems are not only more complex than we think, they are more complex than we can think�. When we start to try to pin down the causes of things that we observe, we find that everything is connected to everything else. That is what systems ecology is about.

Systems ecology focuses on interactions and transactions within and between biological and ecological systems, and is especially concerned with the way the functioning of ecosystems can be influenced by human interventions. The article above describes what may be a relatively simple example of these principles.

Idiocy may indeed be rampant but no more so than ignorance.

good.


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I'm not 100% on this news release. There are as mentioned, some things that coincide to conveniently. As mentioned already it coincides with the introduction of wolves.
MT FWP is feverishly trying to appear to be working hard on getting a handle on wolf numbers in which they really have no idea... but need to look busy. This "finding" would only help their cause and take some pressure off the fact they are clueless on the numbers.

I guess I'm reading it different. I'm not seeing it as a scape goat for wolves .

Although not grizzlies, another study found calves high on the bear menu here in NM.

http://www.wildlife.state.nm.us/publications/documents/NM_Wildlife/archives/spring_2011.pdf

calves and fawns of elk, deer, moose, are almost always very high on the menu for pretty much any bear anywhere, griz or black, AK or NM or anywhere in between. Wolves seem to be not so much infatuated with ungulate infants, though they definitely take them.

Mudhen, thanks for posting this information.

And I'm sure varmintguy's firm opinions are based on reading peer-reviewed articles. I hear that if it's not peer-reviewed, he won't read it.

Maybe WY is different and this report may very well be true, but I am very suspect of any findings of DOW studies or USF&W studies.

For 15+ years the CO DOW did studies of why mule deer populations were declining and came up with various reasons. Hunters were telling them the simple truth is they were shooting too many deer. Guess what, after the all draw deer tags went into affect, the deer population started to rebound.

After the winter of 2007-2008 ,at the hunter round table meetings, hunters were telling the DOW that a pretty big winter kill occurred. The DOW stated they were not seeing that from their computer models. Two years later, they finally reversed themselves and admitted they screwed up.

For several years they were issuing 2000 OTC cow tags in the Flat Tops ( units 25,26).After the first two years, we were telling them the elk were not there and it was not justified issuing those tags. After a few years, they finally relented and cut it to 500,now it is zero.


In 2009 ,I met some college students in Unit 201 doing a study on sage grouse. They were capturing them and then fitting a transmitter. They told me the final cost would be $50,000 per bird after the study was finished.

In 40 years hunting as a resident in CO and being a volunteer and active in the DOW ,I have seen several similar instances. Read their 5 yr hunting structure plan and towards the end,you will see it is all about what will generate the most money with very little emphasis on what is the best practices for the wildlife.

Ten years in NM and I saw the same thing prevail. I found that most of these studies a had a preconceived notion of how they should come out. One such example is the North Dakota study on lead bullets usage in big game hunting which the U.S. CDC debunked.

There are some good guys in the DOW departments, but the upper echelon is not so great, especially when they are appointed by the governor.

No pics
Didn't happen!
Cheers

The report on the cutthroat and grizzlies is a compilation of two separate studies conducted by researchers at Washington State University and the University of Wyoming.