The Kootenai River Eco-challenge!

Imagine yourself fishing in a river where every cast you threw out produced a rise from a hungry trout. Now imagine that this place is in your own back yard here in northern Idaho. Some of you can remember when this was the case for the Kootenai River. The Kootenai is home to fish species such as white sturgeon, burbot, whitefish, rainbow, cutthroat, and bull trout. Unfortunately most, if not all of these, species have been in decline due to man-caused disturbances over the past century. As a result of these events, the Kootenai River has significantly changed in shape, bottom type, and food richness. For example, past attempts to reduce flooding cut off the river's historical flood plain habitat. With no floodplain there is very little addition of nutrients to provide food for organisms at different levels of the "food chain". In addition to all of the changes to the valley floor, the Kootenai River was dammed for flood control and hydropower in the early 1970s near Libby, Montana. Many studies have indicated that large river systems that are regulated by dams for flood control or hydropower may change in types of plant and animal life (algae, aquatic insects and fishes) over time. Studies have shown that this is the case on the Kootenai River, and that Libby Dam is primarily responsible for the depletion of nutrients and the decline in food production in the lower Kootenai River. In a sense, aquatic ecosystems are similar to one's garden. Just as nutrients are needed to grow nice crops on land, nutrients are needed to produce productive fisheries in rivers and lakes. The reservoir behind the dam (Lake Koocanusa) acts as a nutrient trap, retaining approximately 65% of the river's total phosphorus and 25% of the total nitrogen in the lake. Due to slower current velocities behind the reservoir, these nutrients bind to sediments and fall out of suspension making them unavailable to organisms in the river below the dam. Consequently, the Idaho portion of the Kootenai is now considered "nutrient poor." Lower nutrients translate to reduced food production. This is thought to be a major contributor to poor sportfish production over the past two decades. Evidence of species changes in the Kootenai River have been seen at many levels of the food chain. For example, normal insect abundance and species diversity prior to the dam's construction was significantly higher in many areas. Now, insect diversity and abundance are considered low in relation to other northern Idaho rivers. Species such as caddisflies, stoneflies and mayflies have dropped off in numbers, and more "generalist" species such as aquatic worms have increased in many areas. This translates to problems with those fish that rely on insect diversity for survival. Subsequently, studies have also shown shifts in fish species from feeding "specialists" such as trout and whitefish to more feeding "generalists" such as peamouth and large-scale suckers. Recognizing these problems, the Idaho Department of Fish and Game (IDFG) and the Kootenai Tribe of Idaho (KTOI) have teamed up in a full scale ecosystem rehabilitation project. The project is lead by fisheries research biologist Ryan Hardy of the Idaho Department of Fish and Game and aquatic research biologist Charlie Holderman of the Kootenai Tribe of Idaho. The project began in 1999. The ecosystem project has a goal of investigating ways to restore sport and native fish populations in the Kootenai River to self-sustaining levels, adding the Kootenai to Idaho's list of "blue ribbon" streams. We are involved in the second phase of an Adaptive Environmental Assessment (AEA), exploring the prospects of resorting nutrients to the river. Several options are available to do this. One is to add nutrients at a "pump-house" facility, where liquid phosphorous and nitrogen would be delivered to the river from large propane-type storage tanks during the spring and summer when nutrients are in the most demand for biological growth. Reconnecting backwater sloughs and low-lying wetlands is a second method that will restore nutrients to the Kootenai River. The best post-Libby Dam scenario to restore the river's productivity will most likely be some combination of these two methods. Currently, sampling is being conducted. This includes studies of the river's nutrient levels, algae growth, insect life, fish species, and angler harvest. These findings will be used to build a database to determine if nutrient restoration is a practical method to restore native fish and increase angler harvest rates of sportfish. The addition of nutrients to increase fish abundance is not exactly a new science. It is consistently utilized in fish farming to increase fish growth and has also proven to be successful in recovering growth of wild fish populations. For example, a large-scale nutrient enhancement program was implemented in the north arm of Kootenay Lake, BC in 1992 to recover declining kokanee populations. The results showed to significantly increase all levels of the food chain. Within 7 years, kokanee spawners in its two main tributaries increased from 300,000 in 1992 to 2.1 million in 1998. A similar study in the Arrow Reservoir in BC showed that in two years of nutrient enhancement (fertilization), kokanee numbers went from 4.4 million to 10 million and the average size of spawners went from an average of 8.3 inches in 1996 to just over 11.4 inches in 2000. IDFG and KTOIs decision on whether or not to add nutrients to the Idaho section of the Kootenai is scheduled for the fall of 2004. Additional factors, however, such as cost to benefit ratios, the long-term effects of the addition of nutrients, and international considerations (the river flows directly into Canada once it leaves Idaho) must all be taken into account. The hope is that with the addition of nutrients, primary productivity (algae) will subsequently increase. Fish food (eg: insects) will increase and ultimately enhance fish communities. Ecologists call this type of food-chain stimulus a "bottom up" approach. Many exciting things are happening in northern Idaho's waterways. So if you get that fishing bug again, and can imagine yourself fishing a beautiful, productive, and pristine river, keep the Kootenai in mind for future expeditions. By: Ryan Hardy, Fishery Research Biologist, Idaho Department of Fish and Game, and Charlie Holderman, Fishery Biologist, Kootenai Tribe of Idaho