The Lower Boise River through town is considered one of the finest urban trout rivers in the country and we are lucky to have it in our back yard. The Boise River has a good population of wild rainbow and brown trout and Idaho Fish and Game (IDF&G) stocks it regularly with hatchery trout.
To track and manage the trout population, IDF&G does regular electrofishing surveys on the river. They use a population estimate method called a Mark Recapture Survey. They electro-fish a half mile section of river and mark those fish with a fin-clip or tag, then return later to electro-fish the same section of river. Some portions of the fish they catch the second time have tags, and some do not. Using the ratio of tagged to untagged fish they can estimate the population size. For example, if 200 fish were tagged on the first outing, and two weeks later 20% of the second sample are tagged fish from the first survey, that suggests those 200 fish represent about 20% of the whole population — meaning there are roughly 1,000 trout in that stretch of river.
Here is more information from IDF&G about how they work to manage and improve trout populations on the Lower Boise River. For details on each section, see IDF&G's online Fishing Planner which is an excellent tool to help you explore fishing opportunities in Idaho.
One section of river IDF&G has never been able to effectively survey is the reach from the NY Canal Diversion Dam down to Barber Dam. It is very difficult to get the trailer and rafts down to the river and much of the river is so deep that electro-fishing is ineffective.
BVFF has been volunteering at the Diane Moore Nature Center and supporting the new Army Corps of Engineer’s Barber Pool Restoration project . The Barber Pool Conservation Area is a special place and unique in an urban environment and we have been surprised and impressed with the trout population there. Unlike the Boise River below Barber Dam through town, the section of river above Barber Dam up to the NY Canal Diversion Dam is not regularly stocked with hatchery trout. As a result, it has evolved into a wild trout fishery.
IDF&G Southwest Regional Fishery Manager Art Butts would like to get a better trout population estimate in this section, using anglers as the catch method. This “rod-and-reel capture method” is a well-established substitute for electrofishing in water like this, but it takes skilled anglers to catch a good sample size. Art has asked BVFF and the VICE Outdoors community to help them with two rod-and-reel capture surveys in November, on 11/X and 11/Y (time TBD). We will have teams of anglers catching, netting and transporting trout to biologist stations where they will weigh, measure and tag fish.
Flows on the Boise will be down to winter fishing levels and the river will be in prime shape for fishing. To get a good survey we need to put a lot of fish in the net! We are looking for anglers who are familiar with the water above and below the HWY-21 bridge. If you are interested in helping, please reach out to us at conservation@bvff.com. There's also a chance this survey will turn up something extra: IDF&G placed brown trout egg boxes below the Diversion Dam in fall 2024, part of an effort to establish a wild brown trout population in this reach. That first cohort would be about a year and a half old by November — old enough to be catchable size. It'll be a nice bonus if any turn up in our nets.
We're grateful IDF&G is investing the time and staff to get population data for this reach, and for reaching out to our club to help. It's not an easy piece of water to study, and this kind of hands-on population data is exactly what's needed to manage it well going forward.
