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3. Beaver dams - friend or foe of trout??

I recently went into a favorite tributary of the Rifle River (Klacking Creek) for the first time in 10 years to fish the old beaver ponds that I knew and loved during my West Branch/Skidway Lake-era days. I had great success in those ponds with grasshopper imitations (a modified Joe's Hopper) and had hoped to recapture some of this former glory. Much to my disappointment, all of the beaver ponds were completely gone, no sign even of the old dams (which were likely torn out to discourage any beavers from rebuilding them). This turned the little stream back into, well, a little stream, with large areas of extremely tight cover and shallow waters that were impossible to fish. There were still some fishable holes, out of which I pulled two small rainbows and had a couple more hits that I missed, but I would have to say that fish cover in this stream was substantially reduced in addition to the fishable areas of the stream being extremely reduced (at least by fly rod and perhaps encouraging more worm-dunking). And the old arguments about beaver dams warming the water, well, just doesn't hold water - this is a spring-fed stream that always stayed 5-10 degrees colder than the mainstem of the Rifle even when there were beaver ponds. Perhaps one could argue that some nice gravel beds had been opened up to the fish of the mainstem to spawn on that were blocked by the dams, but the creek always had a nice stretch of gravel beds below the last dam which may have even been kept clean by the dams holding back silt and sand.

I believe there was a thread on here some time ago concerning the topic of beaver dams, but we have a lot of new folks so there should be some fresh opinions on this. OK, boys and girls, what do you think about this?

Jonathon

Friend or foe? Both, though I'd have to say that manmade dams and development are the far greater foes, especially when they rob headwaters, tribs, and the downstream areas of cold water. In my old stomping grounds in the Poconos, far more once-cold trout streams were warmed by artificial "recreational" impoundments on tributaries than were ever affected by the chisel-toothed woodchoppers. Personally, I'd like to thank the kind folks of the Midwest for helping to restore our PA beaver populations, even though many of those Midwestern imports have (temporarily) ruined my fishing or scared the crap out of me with their close-range tail-slapping antics.

Sorry G. You know how fond some of us Michigan Boys are for "those PA boys"! We didn't want our cousins over your way to mis-out on all the fun. ;)

They are really re-establishing themselves on the upper Au Sable...The busy little shits think they can stop any river no matter how big. We have been seeing more and more little huts along the edges and if you walk by you can hear them grunting in there.

I still can't figure out how they do it. I will see some of their wounds on the lower portion of a tree, pull out my trusty UN World Food Program Swiss knife, and I'm unable to cut even one wood chip from the tree?!

Spence

Thanks, Spence, but I'm not sure that all of your Midwestern Castor feel the same way about some of "those PA boys" that you do. I remember a pair of them swimming on the surface in a beeline toward me only to submerge suddenly less than 3' away. This left me spinning in circles on the streambed trying to figure out where they were. I wondered if they had mistaken me for a tree and were about to start gnawing on my ankles. :)

That incident was nearly as intimidating as the time a river otter exited a little Pocono stream right between my legs. I had just stepped into the water from a rhododenron tunnel when a submarine-like wake headed through the shallows toward me. As I was wondering how carp had made their way into this mountain trout stream, the wake materialized into a mature (read "big") otter that shot between my legs, up the bank, and into the same hole in the rhodies that I had just come out of.

Yep, ol' Castor canadensis will make you change your underwear, especially amongst those of us who venture out after dark...but I love their architecture and the trout that they grow for us. Also, as I posted on here some time ago, I saw them restoring proper channel complexity in small coastal Oregon streams that had been diked and channelized to provide horse and cow pasture. And believe me, the coastal cutthroat and coho parr were in those ponds THICK. Great shelter in what were otherwise pretty dinky little creeks...

Jonathon

P.S. Spence, they have some SERIOUS TEETH - they are actually a type of rodent, so think of giant aquatic rats with a taste for tree cambium. In fact, being rodents, if they don't constant chew with those teeth, they will grow too long, first starving them and eventually growing backwards into their skulls (and brains - not a pretty thought).

Isn't it interesting that Yellowstone was almost completely devoid of beavers until the wolf was re introduced. Now (since 1995) they are on the rise.
I read somewhere that the wolves prey on the elk so much that the elk no longer have the security to eat the majority of young willow and cottonwood trees that are so important to the beaver's diet.

Good stuff, Tony.

Tony, I believe the phenomenon is called "trophic cascade". A predator is introduced (or in the case of Yellowstone, re-established) and it has a cascading effect on many other creatures found within the food web. In Yellowstone, I have read, the predation of the wolves upon the elk has reduced the elk herbivory on riparian vegetation and this has had a most positive effect on the trout, which rely on riparian vegetation for shading (keeping the waters cooler), cover (dead trees and limbs falling into the water), and food (insects falling into the water from the overhanging vegetation). Funny how when you replace a missing part the whole "machine" works better...

I think it was Aldo Leopold who wrote about taking apart an engine. You have all of the parts & pieces spread out before you, and yet you're not sure how every piece functions in the engine. If you don't understand the importance or function of a certain part, would you throw it away and assume that the engine is still going to work well???

Jonathon

Jonathan-



This is a trick question, right? :-)

Roger...How about just tricky? To me wild trout and wilderness and leaving certain places in nature "wild" (say Yellowstone) may not always work in ways we wish but that is just how it goes. We can't have wilderness and get upset every time something happens there we don't like. Otters like fish, Herons like fish, Osprey like fish, Bears like fish etc. etc. I know it might be inconvenient for us after we plan a dream trip to fish the Slough Creek or Lamar and get chased off by a grizzly but we can't have it both ways.

If left alone long enough it will return to mean.

IMHO

Spence

Hope we do recognize some of the great backwater fisheries, and especially tailwater fisheries that dams produce. And that says nothing about regulating water flow that can cause massive flooding damage at times. Anyone follow that California community that their beavers backed up waters throughout the community, causing property damage? And who on this thread, lives along that Touchet River in WA ST.? I have guided, and fished all over that state, and did not know where it was located...had to google it up. Sure like those bug photos.

"This is a trick question, right?"

Not if you understand ecology (at least as much as we humans can understand it). And that tends to be the problem - people do NOT understand the connectedness of things in nature, and so think they can modify it to suit their needs without worrying about the consequences. And there are ALWAYS unintended consequences, many if not most of which are bad for both ecosystems and us.

I read an article on trout stream riparian management on the Michigan DNR website a few years ago that made a lot of sense. It said that due to logging in the vicinity of trout streams, there is currently more aspen in riparian zones than there was before the logging era. As aspen is the favored food of beavers in these parts (as well as other places I'm sure), more abundant aspen in riparian zones means more beavers. Too much of any one organisms in any ecosystem is going to cause the detriment of others, so too many beavers equals too many beaver dams, which in excess can warm the waters and block fish movements (and possibly reduce spawning habitats by burying gravel beds). However, I suspect the majority of damage done by beavers is not to the trout streams themsleves but to the ambitions of property owners who live along trout (and other) streams...So you want less beavers? Let riparian zones grow back into coniferous forests and the beavers will have less food.

Jonathon

Here's a funny one on beavers. I guided in Bristol Bay on the Alagnak River in the mid 80's. A huge fear to the angler was to drink water from streams, or rivers that surely had beavers crapping in the water upriver. The thought of getting beaver fever had folks boiling their water. I salmon fish/steelhead fish by putting loops of line in my mouth, and then casting. There was always the thought of getting beaver fever, and I spit a lot, and often when I fished. And there were definitely beavers on the rivers I fished. And, I think the bottomline is....maybe at one time the beavers were the source of Giardia (sp?) up river, but now humans are upstream in good numbers as well.

Giardiasis can also be transmitted by other rodents like muskrats. It can be carried by domestic animals and during the rainy season, fields treated with manure can wash the spores (more properly "cysts") into the watershed.
It isn't advisable to drink any water that doesn't come from a tap unless it comes directly from a spring.
Human transmission does occur, but usually from daycare centers or food handlers.

I once got away with drinking water directly from a small, spring-fed trout stream, with no bad consequences whatsoever, but I would NEVER do it again! Always use a good water filter!

Jonathon

Lloyd's right: it's both. They can add large pool habitat to streams that otherwise wouldn't have them, and these may also serve as a winter or low-water refuge, so they add some resilience to the system. They can make for great fishing.

On the other hand, there are many negatives:

• They can warm the water (sometimes so slightly it doesn't matter).
  
• They can block fish passage for spawning or moving between different feeding/winter habitats.
  
• They can trap silt. This can flat-out kill a trout stream, and over the long term can turn a gravel-bottomed stream into a continuous series of very shallow, mucky-bottomed lakes.
  

I think the bottom line is probably that beaver dams are good in systems that flood occasionally and wash the dams out, and bad in extremely stable systems where they get built up so tall and thick that they block fish movement and trap years or decades worth of silt.

Just as a side note, I'm pretty sure it isn't even advisable to drink water directly from springs...Or so says a sign at just about every spring pool in the Ozark National Scenic Riverways.

My father got a really bad case of Giardiasis from drinking out of an incredibly pristine Alaskan snowmelt stream. So I was taught from pretty early on to be careful about where I drink from. If I'm gonna be away from civilization long enough that I can't carry enough water I always use a filter, even if whatever waterway I'm on has excellent water quality. It's a whole lot safer and they aren't too expensive either.

It's probably like the old Greek philosophy: "everything in moderation". Too many beavers create the problems Jason has outlined above, yet in the right numbers they can considerably enhance the productivity of a small trout stream. Achieving balance in these days of constant human interference, however, is probably damned near impossible - per the example of beaver abundance being excessively high from dominance of their food source (aspen) in riparian zones of trout streams due to human logging of coniferous trees...and maybe we killed off the predators of beaver too (not enough otters controlling the population)??

I do miss those ponds on Klacking Creek, but if it opens up more spawning gravel to trout on the mainstem of the Rifle, well perhaps they won't have to be stocking it so heavily and can rely more on natural trout reproduction. However, those beavers in Oregon were helping salmonids in those small coastal streamns that had modified by human activities, at least in the short run.

Jonathon

Otters eat beavers?? I didn't know that!!

I don't know for sure, but I wouldn't be surprised if they prey on young beavers. I'm not sure what else would, other than perhaps large great horned owls? If others on here know please chime in.

Jonathon