Monday, September 11, 2006

of trout and tree-gnawing rodents*


imagine the search engine hits I would get if I dared to say the word "beaver" in the title! What a crazy world we live in.

I had another classic adventure day at work. I was a little leery after the last day I went on stream detail, ending up wading through a mucky beaver-infested willow jungle of a supposed trout stream. The last straw was falling face-first into the muck as I was crawling on all fours trying to avoid sinking up to my knees in the goo at the bottom. I did what any sensible person would do as I realized I was completely soaked. I laughed my arse off.

This day promised to be better. John and I were going to check a small tributary of the St. Croix River, which five years ago was found to have a healthy population of wild brook trout and was then designated a trout stream. The waters in the area where we were going, far south of where the office is, farther south from where I live, are vastly different. The St. Croix Valley is a geographical wonder in an area of relatively flat land. High bluffs tower over the river bottom, sometimes exposing layers of sedimentary rock over older layers of volcanic basalt. The beauty of this "canyon" is breathtaking.

Because of this geology, the steep bluffs, groundwater from above seeps into the St. Croix through cracks in the bedrock, and occasionally these seepages become large enough to sustain flow year round and create a stream channel. The cold temperature of the groundwater is optimal for brook trout (Salvelinus fontinalis), which somehow some time long ago found their way into these little streams. The main flowage of the St. Croix River is too warm for them in the summer.

Armed with a jon boat with 15 horse motor, backpack gasoline-powered shocker, and waders, we set out. The stream was about two miles downstream from where we launched the boat, and we motored past towering bluffs and cliffs, and floodplain forest. Asters, some yellow sunflower-family flowers, and even cardinal flower bloomed along the banks. Vultures and sandhill cranes soared overhead; the sandhills looked to be part of a migrating flock. Great blue herons stalked the banks, while belted kingfishers chattered from branch to branch.

We turned off into a side channel about a mile downstream. The river channel here is braided, meaning there are numerous side channels that are definitely worthy of exploration, although most canoeists choose the main channel.

Our destination, according to the GPS, appeared as a sand bar delta with a small flow entering at the downstream side. We ate an early lunch, knowing that it might be difficult walking and we might need the energy. It was an incredibly remote, quiet place. The day was overcast, and we noted the chill in the air. I wore a heavy sweatshirt, and still felt chilled.

Finally we put on our waders and got started. I removed my sweatshirt, thinking that with it on I would work up a sweat and end up completely chilled on the ride back. The stream at the mouth was so narrow that John and I could not walk side by side; sometimes I walked up on the bank. He had the backpack electrofisher on his back, and I carried a backpack with a bucket, clipboard, and scales. The GPS unit was clipped to my wader suspenders.

About fifty yards or less upstream, we encountered the first beaver dam. Upstream was a pool that was deep enough to harbor a few aquatic plants. We breached the dam a little, causing a rush of water flowing downstream, and climbed into the waist deep water. Beyond the head of the pool, we lost the stream channel in the tall grass. There was water flowing among the grasses, it just did not flow in any one discernible channel. After fighting upstream for a while, not knowing where we were headed, we decided that I should walk ahead and see if this stream resolved itself into a channel anywhere nearby. I fought tall grasses, small willows, and shallow water over muck until I did find a place where I could see clear water flowing over sand. I made my way back to John, and realized with all the work of moving through tall grass I was sweating in my neoprene waders.

We found the channel and started electrofishing. Within about a one hundred yard reach of clear water we shocked two brook trout, 9 1/2 inches each. If you've never seen brook trout, and I have had precious little experience with them, they are perhaps the most beautiful fish in the world. Grayish green back with bright red and blue and yellow spots, and some iridescent pink on the sides. I was thinking this place was looking heavenly; crystal clear water running over sand, with beds of green watercress and forget-me-not blooming late, their blue contrasting with the yellow of beggartick and the orange of jewelweed.

Then we ran into more beaver dams; the going got more rough, the bottom muckier, obstacles of beaver logs every ten yards or so. Finally we lost the stream channel again. We measured the trout (kept alive in a five gallon bucket), and took scale samples. One male and one female. Perhaps the only breeding pair left in this stream. Then I looked upstream and saw nothing but marsh and muck. Somewhere there was cold flowing water, but without a discernible, hard-bottomed channel it was not worth sampling any further. We turned back.

The downstream walk was trying. Although I knew we were on the down side, heading home, and in no danger of getting lost, I found it was harder and harder to lift my wader-clad legs over beaver logs, that and getting mired in muck way too often. I was drenched in sweat, envisioning myself getting stuck, unable to pull myself out of the muck, spending eternity here within reach of the river. Then, as I stepped into the elusive stream channel once more, I rammed my right shin straight into the end of a beaver-knawed stump. The pain made me see stars.

But I was getting closer to the river and our boat, and I plunged onward until finally I was there. We rested for a minute, drank water from our bottles, then pushed the boat out and motored back upstream. I was getting chilled from my sweat-drenched shirt, but I wanted it to dry out a bit. I was grateful for the warmth of my sweatshirt when I finally pulled it on at the boat landing.

I have heard for a long time what beavers can do to trout streams in this area. I have seen it once or twice. But today I saw it first hand. Five years ago, according to the stream survey done then, there was a stream channel and they sampled ninety adult brook trout and numerous young-of-year. We got two adults. But, where there is a male and female, there is hope.


madcap said...

Lots of beaver here, of course, clogging everything up. They're rodents indeed, and they breed like it, there are just too many of them. Every year on our local "river" Fish and Wildlife has to bust up the dams, but they only relocate so it's an endless process.

You hear about the pendulum swinging this way or that, but how is it that it never seems to hit that middle point? Are we so daft that we can neither control them to a reasonable number nor keep ourselves from wiping them out altogether?

Those brook trout have my hearty wishes for an abundance of wee wigglers.

the dharma bum said...

deb - great post. you certainly piqued my curiousity with your teaser comment on my blog and when i started reading i was ready to demand some GPS coordinates, but that's too bad about the population being decimated like that.

that is THE stretch of the st. croix that i love so much and have paddled a few times a year for the past several years... i'm trying to figure out which of the tiny feeders that i've noticed might be the one you're talking about and i have an idea. those backwaters are definitely my favorite. i stay off the main channel as much as i can.

anyway, if you would be so kind, i'd love some coords or something just to get a better idea of where you're talking about. if it's not a state secret or something. :) shoot 'em over in an e-mail if you feel like it.

thanks for an enjoyable read!

Sandy said...

I am glad I wasn't there, but it was sure interesting reading. Next time, could you take a camera, so you could get a few shots??

Floridacracker said...

Well, I loved this adventure. Any combination of fish, wildlands, and sweaty women is ...

I'm just kidding.

I had not thought of Beavers having that effect before. It seems pretty dramatic.

Are results like that enough to cause some action by the state? How likely is a spring thaw flood to remodel this stream and debeaverdam it?

pablo said...

Coincidentally, I was reading a section of Hal Borland today that discusses this very same thing having happened in Connecticut in the '60s.

Girl Gone Gardening said...

Thats a fascinating post for sure! thanks :)

clairesgarden said...

what a great job!

Sue said...

I had an adventure very similar to yours a few years ago, while surveying for freshwater mussels in a stream in North Carolina. We were doing a bridge-to-bridge canoe survey, and so had to drag the canoe over beaver dams and shallow runs all day. Ah, the life of a field biologist!