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Saturday, April 4, 2009

San Juan River







Last week, I got out for a rare week of field work on the San Juan River. The unfortunate thing about moving up in the world of biology is that you seem to get further and further away from what it was that got you into the job in the first place, being in the field.

The San Juan River flows through the very southeastern corner of Utah ending at the eastern end of Lake Powell. The headwaters are in the San Juan mountains in Colorado, so while where we were floating was very much the desert, the river is fed by distant snowfall. And like all the rest of the major rivers in the West, the flows are regulated by dams.

My trip down the San Juan was for the San Juan River Recovery Program. The San Juan is home to two endangered fish, the Colorado pikeminnow and the razorback sucker as well as three native fish which are not endangered, but are considered tier 1 or the most sensitive by Utah, the bluehead sucker, flannelmouth sucker and roundtail chub. The Colorado pikeminnow can grow up to 6 feet long, although fish this large have not been seen for many years. The razorback sucker is aptly named with a prominent, narrow ridge between its head and dorsal fin. Historically, these big river fish, especially the pikeminnow migrated hundreds of miles to their spawning grounds. Now their accessible spawning areas are much reduced by both large dams, small diversions and in the tributaries a complete dewatering. Although some of us may wish for the dams not to be there, the big ones we have are not going anywhere anytime soon and the goal of the recovery programs is to recover the species while still allowing for water development. It may seem like these are pretty contradictory goals, and in my more cynical thoughts, they very much are, but the reality is that humans need water too and while we definitely should be using it wiser than we often do, we do get water in the river and for the fish from these dams too. Part of the recovery program is flow requirements for critical habitat that requires minimum flows and flows that mimic a natural hydrograph during critical times for the fish.

Another major threat facing these fish, is the introduction of non-native fish. In the San Juan, the primary culprit is the channel catfish. I believe this was introduced to the San Juan through its stocking as a sport fish into Lake Powell and other reservoirs. The catfish provides a double whammy to the pikeminnow. Large catfish are very predacious on smaller native fish and while pikeminnow are also predators and eat small catfish, the catfish have spines which can get stuck in the pikeminnow as they are trying to eat it and can kill the pikeminnow.

So, the purpose of this and many trips down the San Juan, Green and Colorado Rivers is non-native removal by electroshocking. What this consists of on these large rivers is a crew of at least 5 people, 3 boats (2 electroshockers and 1 gear boat). The electroshocking boats are set up to send a current into the water at a voltage that stuns the fish, but doesn't cause any long-term harm. One person rows, keeping the boat as near the bank as possible while another stands at the front of the boat with a net, netting up all the non-native and endangered fish they see. The non-natives are counted, measured and removed from the system, while the endangereds are scanned for a tag, measured, weighed and returned to the river. The tag has an unique number so we can tell where it has moved from and how much it has grown.

The trip down the San Juan is beautiful and is very popular with recreational boaters, due to a fairly peaceful float through tall canyons of limestone and sandstone. There are a number of side canyons and hikes to explore as well. Unfortunately for a work trip, while it is still beautiful and enjoyable, you don't get to sit back and enjoy the scenery too much. You are either focused on rowing (trying to keep the boat near the shore without running into the shore, rocks or trees, while keeping your eye out for fish and turning the boat in whatever direction the fish are so they can be netted) or standing at the front of the boat, focused on the water in front of you ready to lunge with your net when something pops-up for sometimes just a second before it sinks back into the silty water. Another treat for all on the San Juan, is the last 12 or so miles which were inundated by Lake Powell when it was full. This deposited a lot of sand and left a nice bathtub line on the rocks. This stretch of the river is very flat and slow and you have to keep your eyes peeled for where it is deep enough so you don't get stuck in the sand bars. On my trip, this was also the day it was rainy, snowy and very windy, and the wind always blows upstream. This meant sometimes you were rowing as hard as you could just to stay still.

In spite of the wind and cold weather, it was a great trip. We removed a few thousand catfish, recaptured a few hundred pikeminnow, and a handful of razorback suckers. As far as the non-native removal goes, the San Juan is a place where we actually seem to be making some progress, over the last couple years, the catfish we catch are smaller and fewer. The San Juan is also being helped out by the drought in this aspect too. When Lake Powell receded from its full height, it created a waterfall about 10 miles downstream from where you take out from the river. This waterfall is preventing any additional catfish from invading as well as all of the other non-natives which are in Lake Powell. The downside is that any natives that go over this waterfall, are stuck downstream where they have little chance of surviving.

For me, this trip was a much needed reconnection with the river and reminder of why I spend most of my working hours in a office trying to help conserve our native fish.

*pictures will be coming soon, they're on a different computer

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