Restoring Cady Creek’s Brook Trout Population

Restoring Cady Creek’s Brook Trout Population by Managing the Eau Galle River Watershed – PART 2

Kasey Yallaly

Back in 2020, I wrote an article about our brook trout restoration efforts in Cady Creek. If you dig this article up from the archives, you will see that we have come a long way since 2018. To refresh everyone’s memories-the brook trout population in Cady Creek was in extreme decline following the invasion of brown trout in 2006. Brown trout densities continued to increase to the point that they surpassed brook trout densities up until our removal efforts began in 2018. We have documented the exclusion of brook trout by brown trout in several other streams, to the point where brook trout are almost completely gone. In order to prevent this from occurring in Cady Creek, we began with removing brown trout from Cady in 2018 and have continued every fall since then.

I have good news to share if you are a brook trout fan- we have documented a strong positive response of brook trout to our brown trout removal efforts. Brook trout densities and natural reproduction continue to increase. Brown trout have continued to decline, and we removed the fewest brown trout to date in 2023. Brown trout densities have dropped from a high in 2021 of 1,891/mile to 439/mile in 2023 (see graph).

Catch rates of brook and brown trout in Cady Creek at the Station 2 trend site.

Each fall, we use electrofishing gear to remove brown trout in about 4.5 miles of Cady Creek. This year, we removed a total of 1,582 brown trout with 66% of those fish being young-of-year brown trout or trout that hatched this past spring. From this data, we know that adult brown trout from the Eau Galle River are utilizing Cady Creek as a spawning and nursery stream. Unfortunately, there is no barrier that prevents brown trout from moving into Cady Creek in the fall to spawn and it would be impossible to create a permanent barrier because of the relatively low gradient of lower Cady Creek, meaning that a barrier would cause water to back up for a long length of stream which would severely degrade habitat and water quality. Therefore, to create a temporary barrier, we were able to acquire part of a weir from another fisheries team in Peshtigo, that will help us create a temporary barrier.

Weir installed in lower Cady Creek in 2022

This type of weir is designed to allow water to pass through while directing trout that are moving upstream into a trap. Any fish caught in the trap can then be moved upstream or downstream or removed. We placed the weir in lower Cady in early fall of 2022. No fish were trapped but the weir did act as a barrier to upstream passage. Leaf debris was an issue, which meant that the weir needed to be cleaned twice a day.

In order to narrow down an appropriate timeframe to operate the weir, we needed to know more about seasonal trout movement. Therefore, we teamed up with Matt Mitro’s (DNR Research Scientist) research crew to devise a trout movement project. Matt is also interested in brook and brown trout passage through beaver dams and with several new beaver dams popping up on Cady Creek, a project fell into place that could help to answer both of our questions. We installed 2 PIT tag arrays in Cady Creek upstream and downstream of a beaver dam. PIT tag arrays are basically a series of wires that are installed within the stream that will detect fish that are tagged with PIT tags. These are passive arrays, meaning that no active tracking of fish is needed. Each time a fish that is tagged passes through the array, the array detects that specific tag number and records that information along with the date and time that the fish passed by. We PIT tagged a total of 862 brown and brook trout within the Eau Galle and Cady Creek to track seasonal movements of fish and gain additional data on growth rates. PIT tags are the same thing that dogs and cats are “microchipped” with, and each animal’s tag is a unique number.

The data collected from this project will help inform us as to when the weir should be installed within Cady Creek to prevent brown trout moving upstream into Cady from the Eau Galle River to spawn. This will reduce the amount of effort needed to remove brown trout each year and will reduce the number of brown trout removed overall. Brown trout removals will also continue each fall. Trout fishing regulations were also recently changed and a new regulation for Cady and Pine Creeks will go into effect on fishing opener of 2024. The new regulation is a daily bag limit of 5 fish with no length limit for brown trout and all brook trout shall be immediately released. Anglers are highly encouraged to harvest brown trout in these streams! PIT tags were inserted into the body cavities of the trout, so no need to worry about crunching into a PIT tag when you eat a filet!

Stream Survey Report: 2022


The Baldwin DNR Fisheries crew surveyed a total of 64 trout stream sites this year on streams in Pierce, St. Croix and western Dunn counties. The surveys went well with the weather cooperating and very few large runoff events. 

Overall, trout densities in most streams are very stable compared to long term averages. Total trout densities were lower relative to last year, due in large part to the high natural reproduction in 2020 and 2021 making total trout numbers extremely high in 2021. 

In most streams, natural reproduction was low this year compared to long term averages but adult trout numbers were high in part due to the 2 large year classes of trout from the large hatches in 2020 and 2021. 

The drop in trout densities experienced this year is likely a good thing and nothing to be concerned about as trout densities in 2021 were likely higher than carrying capacity for most of these streams and competition for resources was high. With relatively lower trout densities and low natural reproduction this year, we should likely see a jump in size structure in the near future. 

Some additional trends resulting from our survey work this year were drops in brook trout densities in streams where both brook and brown trout occur. In many brook trout dominant streams, however, densities and natural reproduction are up from previous years. There is also promising news from the Cady Creek brook trout restoration project which shows brook trout densities higher than in previous years and densities that are finally higher than brown trout densities. 

The Willow River Race Branch looked better than ever with good numbers of adult brown and rainbow trout. This year seemed to be the year of large brook trout in our surveys with a few fish larger than 13 inches captured in several streams. 

We surveyed 11 trout habitat improvement projects for post-habitat evaluations and all of them look great as far as trout densities and natural reproduction with densities higher than prior to project completion in all projects. Overall, the trout populations are in great shape with many aspects to look forward to in the near future.

2021 Stream Sampling Trends

2021 Stream Sampling Trends: A Banner Year for Trout

Despite the drought conditions and warm summer, 2021 was a banner year for trout in this part of Wisconsin in terms of overall trout abundance and natural reproduction. Numbers of all size classes were higher than the average over the last 10 years on most streams. However, the numbers of age-0 (young-of-year, fish hatched this spring) and age-1 fish (fish hatched the previous spring, spring 2020 in this case) were through the roof in many streams! This was encouraging to see during the course of our summer sampling as many anglers expressed concerns about the trout population in the Rush River and others following the major flood event in late June 2020. The Rush, in particular, was impressive as always producing higher than average numbers of all size classes of fish from young-of-year fish up to adults with abundances of over 7,000 fish per mile. We completed a comprehensive survey of the Rush River this summer and I will wait to give away those details at the spring KiapTUWish meeting. Brook trout abundances were also higher than average in most streams as well including in the Rush River which was great to see. We also captured a record number of tiger trout within our surveys this year as well. The stream with the highest densities of trout this year was Pine Creek with over 10,000 brown trout per mile! Most of the fish here were either part of the age-0 (2-5 inches) or age-1 year class which is made up of fish in the 5-8 inch range. This was the theme for many streams, meaning that fishing will be very good in the next 1-3 years as these fish mature. Many factors may influence the survival of eggs/fry to the juvenile stage but one of the more influential factors is the timing of spring flood events. Flood events at the late egg stage or soon after fry have emerged will likely result in a very poor year class of trout. For example on the Kinnickinnic River, the graphs below show the large flood events in the early spring of 2019 and the steady low flows of 2021 which resulted in very poor year classes of trout in 2019 and very strong year classes of trout in 2021 according to our sampling (keep an eye on the vertical y-axis and the difference of the cfs between the graphs). The timing of these flood events can be a predictor of the strength of the year class of trout and how good the fishing may be in years to come. 

-Kasey Yallaly

Graph of  Discharge, cubic feet per second