Conserving Native Brook Trout: Strategies to Combat Climate Change, Non-Native Species, and Habitat Loss

Brook Trout are declining in large parts of their native range due to a host of factors. Non-native trout (Larson and Moore 1985) - Brown Trout, in particular (Huntsman et al. 2023, Kelly et al. 2021, Valerie and Daniels 2021) - habitat losses and historic degradation (Stranko et al. 2008, Haxston et al. 2020), stocking of non-indigenous Brook Trout strains (Bruce et al. 2020, Erdman et al. 2022, Hargrove et al. 2022, Johnson 2022, Kazyak et al. 2022), climate change (Andrew et al. 2022, Maitland and Latzka 2022), and the combination of all/some of those factors occurring together (Johnson 2022). Brook Trout are booming in much of their non-native range and creating issues for other native trout species (Al-Chokhachy et al. 2021, Manning et al. 2022). Interestingly, Brown Trout in their native and non-native ranges are declining for many of the same reasons Brook Trout are declining in their native range (Santiago et al. 2016, Casanova et al. 2022, Vera et al. 2023). The natural world is such a strange thing sometimes.

I don't know if there is a more beautiful creature than a Brook Trout.

In the above paragraph, I tried to write "all sciency" and tried to limit myself to articles since 2020 though that was a bit harder for historic degradation. That is my attempt to convey that we know quite a bit about Brook Trout conservation. Though, I would also argue that there is much we do not know. In particular, if you really dig into the articles that were cited, you will notice that they are rather location specific. For example, Brook Trout stocking in some places have had little effect (White et al. 2018, Lehnert et al. 2020) but in other places, it is one of the most significant issues facing Brook Trout (Erdman et al. 2022, Hargrove et al. 2022). The natural world is such a strange thing sometimes.

Brook Trout Conservation

One thing about Brook Trout conservation that I think is rather evident is that while place matters, quite often the stressors are the same or at least very similar. A recent e-mail with a friend in northern Wisconsin really brought this idea home. The causes for Brook Trout declines in northern Wisconsin were much the same as they were for Shavers Fork and the rest of West Virginia - where much of my thinking about Brook Trout conservation were shaped. This post will certainly overlap with a post I wrote over a year ago, Can We Restore Native Brook Trout? That one was a little more personal, a trip down memory lane, this post is a bit more distanced view.

Historical degradation of Shavers Fork in West Virginia. This unnaturally wide and shallow reach with relatively litte riparian cover is not helping native Brook Trout.

There are a number of commonalities among native Brook Trout declines in Wisconsin and West Virginia. First, they share similar historical degradation that impacts their streams today. Similarities in how logging has affected streams in West Virginia and northern Wisconsin are quite striking. The "cut over" just came to West Virginia a little earlier. Both states have significant National Forests - Monongahela National Forest and small parts of the Washington and Jefferson National Forests in West Virginia and Chequamegon-Nicolet National Forest in Wisconsin - where many of the native Brook Trout streams flow. Streams are often unnaturally widened and may contain more sediments due to the history of logging in their watersheds. This leads to degraded habitat quality and reduced quantity along with increasing water temperatures.

One of those Shavers Fork (WV) non-native Brown Trout that looks like it has taken more than its share of food.

Two other important commonalities are the negative effects of non-native Brown Trout and climate change. There are places where Brook and Brown Trout can coexist, both in good numbers, but that has generally not been my experience. In Shavers Fork, there were Brook Trout in the mainstem but by far, their largest populations were in the river's tributaries. We would capture some larger Brook Trout in the mainstem but most of them and probably all of their reproduction occurred in the tributaries. The mainstem gave them better access to food (Petty et al. 2014). And in both places, climate change is a significant issue (Merriam et al. 2017, Maitland and Latzka 2022) which is exacerbated by historical degradation and Brown Trout competition and predation.

A Shavers Fork tributary - one where Brook Trout dominate and Brown Trout are rare or entirely absent.

A last important commonality is a desire to do something about the issue. Both states are quite invested in preserving native Brook Trout, which I think is the case for most states in their native range. And another commonality, both states are quite less than perfect in their protection of Brook Trout. The question becomes, what can we do to preserve Brook Trout within their native range given these challenges?

Expanding this conversation to my home waters of the Driftless Area, the challenges are much the same. The biggest difference is that historic degradation in the Driftless Area is most due to early efforts to convert the landscape into an agrarian landscape. They were certainly successful but the cost was that the stream valleys were filled with cultural sediments which greatly altered our valley and their streams. I would also argue that the challenges that Brown Trout present are even more significant in Driftless Area because the area is home to some of the highest density Brown Trout populations in the World. Rather than go further down that road, I have written about that elsewhere.

• What Did the Driftless Look Like?

• Driftless Stream Corridors - From Past to Present

• The Re-birth of the Driftless

• Native Brook and Non-Native Brown Trout: Towards a Better Understanding their Distributions

• Can We Restore Native Brook Trout?

• Climate Change - Comparing the Effects on Brook and Brown Trout

• Stream Restoration, Improvement, or Manipulation - Whatever You Want to Call it...

• The Diversity of Brown Trout and What it Means Here in North America

Management Options

OK, so what can we do about these issues? At first blush, the solutions seem simple, after all, we know the main causes for Brook Trout declines. And some solutions are easy to implement. First of all, we can - and we have - gotten smarter about how we use hatchery Brook Trout and where we stock non-native trout. Though I do agree, we could do better. Furthermore, I would argue that restoration of Brook Trout in much of their range is not practical or maybe even possible. For example, the sheer number of miles and number of Brown Trout that would need to be removed from many Driftless watersheds would be enormous. The costs would be exorbitant, the will to do so is lacking, and the solutions are often not likely to be successful in many places in no small part because of the land use changes, historic degradation, and invasive Brown Trout are so well established. Of course none of that means we should sit on our hands and no nothing (and we're not).

In essence, the above paragraph is the classic story of fisheries management - we live in an imperfect world, are not happy with it, and want a better world, knowing it will never be perfect. There are many great examples of successful restoration of native trout (Wood et al. 2018, Hoxmeier and Dieterman 2020, Budy et al. 2021, Pechacek 2022, among many others). Here in my part of the Driftless, Brook Trout are primarily in places where Brown Trout are not. There are a smattering of brookies in the Brown Trout dominated streams and places but generally the are quite rare in those places. We electrofished a popular section of the North Fork of the Bad Axe a few summers ago and caught two Brook Trout - and over 400 Brown Trout.

Constructed fish barrier on Hermosa Creek - native Colorado River Cutthroat Trout persist above the barrier, below the barrier we also caught Brown, Brook, and Rainbow Trout (and cutbows).

I started writing this post before reading Chris Hunt's blog post on Hatch Magazine's website, Have We Taken Our Love For Native Trout Too Far? which drew a good bit of attention. I do not totally disagree with Chris and think some people are reading more into the article than he is saying. If I get his larger point, it is, restore native trout where it makes sense, but it doesn't make sense everywhere. Or maybe better put, it isn't possible everywhere within the native ranges of native trout species and subspecies. Of course, I think that argument is built on a rather shaky foundation. There are not many places where many people are concerned that we are doing too much for native species.

I think part of that comes from a Western US perspective that I am less familiar with. Native trout are "simpler" here in the east - we have two native species - Brook and Lake Trout - and not the multitude of species, subspecies, and strains they have in the west. Or at least, we recognize many fewer strains of Brook Trout and have not called them subspecies. And there are great strides we can make with Brook Trout but it will take some effort.

I would like to see this be the regulation on more trout streams. Eat a brown, save a brookie.

Here, in my part of the Driftless, we see most of the Brook Trout populations are above barriers like the Seas Branch, Maple Dale, and Jersey Valley dams in the West Fork of the Kickapoo River watershed. In streams that drain directly into warmwater rivers like the Mississippi, lower Kickapoo, or Wisconsin Rivers. Or in streams, that for some reason(s), lack Brown Trout or lack them in the numbers that so many central Driftless streams possess. Why those streams lack Brown Trout is a particular interest of mine. Understanding this should give us insights into how to better protect Brook Trout. In a few cases, there are significant Brook Trout populations in headwaters upstream of where Brown Trout exist. However, I fear that the decline of these Brook Trout populations is a near inevitability. They just face too many challenges and some of our best, most productive Brook Trout streams are only Brook Trout streams because of barriers and the removal of Brown Trout.

Brook Trout populations in the southern Driftless of Wisconsin are largely limited to small reaches of stream above barriers to Brown Trout dispersal (Olson et al. 2024). Brook Trout exist largely in places like Maple Dale and Seas Branch where they have been restored above a barrier by removing invasive Brown Trout or in streams that drain into warmwater rivers like the Mississippi and Wisconsin Rivers or lower reaches of the Kickapoo River. Similar efforts - without a barrier - have occurred on Melanchthon Creek, which is an experiment in process. And the barriers on Seas Branch and Maple Dale Creeks are proposed to be removed which will almost certainly result in Brown Trout recolonizing those reaches. Those may become two more experiments if barriers are not added to the dam decommission plans. I have a hard time seeing how we are "doing too much" for native fishes when I see things like this.

Keeping native fishes above barriers is not a solution without its issues, though I would argue that in places it may be the only potential solution. As I am sure you probably know, we are typically restoring connectivity as fisheries management practice because connectivity produces healthier, more genetically diverse fish populations. We have spent millions - maybe billions - of dollars to remove dams and replace culverts and bridges that were barriers to dispersal. Barriers lead to a loss of spawning habitat (Poplar-Jeffers et al. 2009), the removal of habitats for critical life history needs (Ridgeway 2008), genetic drift (Olson et al. 2024) and inbreeding depression (White et al. 2023), and generally a depression of fish populations and species (Radinger et al. 2017). There are certainly tradeoffs with barriers but they have been shown to be effective in preserving Brook Trout (Kirk et al. 2018, Olson et al. 2024)

Management Recommendations

1. Don't stock Brown Trout in places where Brook Trout stand a good chance of persisting. Brown Trout are, I would say, without question, the largest single source of Brook Trout declines. Where there are Brown Trout, there are fewer Brook Trout. There is a ton of evidence to support that statement.

2. I'll go a step further, don't stock Brown Trout unless there is a very good fisheries management reason to do so. Rainbow Trout are, well, dumber, and more likely to return to the creel - that is, be caught and kept, if that is the goal of the stocking. Rainbows are also generally less expensive to grow and stock.

3. Do what it takes to protect the native Brook Trout fisheries we do have. Outside the Driftless Area, Brook Trout are quite a bit more well distributed and established. Here in the Driftless, especially the middle and southern Driftless Area, Brook Trout populations are generally limited. Where Brook Trout exist in solid numbers, we need to do what we can to protect them.

4. Where it makes sense, increase harvest on non-native fishes and decrease harvest of Brook Trout. I don't think that catch and release of Brook Trout is generally necessary - they are a generally short-lived species - but in places, particularly where Brook and Brown Trout co-occurr, harvest of Brown Trout and protection of Brook Trout are essential.

5. We need to understand the issues that come with barriers as a management tool - but strategically embrace them. There is little question that in much of the Driftless Area, Brown Trout are the largest negative on native Brook Trout. The recovery of Brook Trout populations after Brown Trout have been removed is evidence of this. We likely need to move some Brook Trout between these restored reaches to increase gene flow.

Literature Cited / References / Reading List

Al-Chokhachy, R., Lien, M., Shepard, B.B. and High, B., 2021. The interactive effects of stream temperature, stream size, and non-native species on Yellowstone cutthroat trout. Canadian Journal of Fisheries and Aquatic Sciences, 78(8), pp.1073-1083.

Andrew, R.G., Schwinghamer, C.W., Hartman, K.J. and Briggs, E.E., 2022. Climate change influence on brook trout populations in the Central Appalachians. Ecology of Freshwater Fish, 31(4), pp.710-725.

Bruce, S.A., Kutsumi, Y., Van Maaren, C. and Hare, M.P., 2020. Stocked‐fish introgression into wild brook trout populations depends on habitat. Transactions of the American Fisheries Society, 149(4), pp.427-442.

Budy, P.E., Walsworth, T., Thiede, G.P., Thompson, P.D., McKell, M.D., Holden, P.B., Chase, P.D. and Saunders, W.C., 2021. Resilient and rapid recovery of native trout after removal of a non‐native trout. Conservation Science and Practice, 3(2), p.e325.

Casanova, A., Heras, S., Abras, A., Roldán, M.I., Bouza, C., Vera, M., García-Marín, J.L. and Martínez, P., 2022. Genomic hatchery introgression in brown trout (Salmo trutta L.): development of a diagnostic SNP panel for monitoring the impacted Mediterranean Rivers. Genes, 13(2), p.255.

Erdman, B., Mitro, M.G., Griffin, J.D., Rowe, D., Kazyak, D.C., Turnquist, K., Siepker, M., Miller, L., Stott, W., Hughes, M. and Sloss, B., 2022. Broadscale population structure and hatchery introgression of Midwestern Brook Trout. Transactions of the American Fisheries Society, 151(1), pp.81-99.

Hargrove, J.S., Kazyak, D.C., Lubinski, B.A., Rogers, K.M., Bowers, O.K., Fesenmyer, K.A., Habera, J.W. and Henegar, J., 2022. Landscape and stocking effects on population genetics of Tennessee Brook Trout. Conservation Genetics, pp.1-17.

Haxton, T., Ball, H. and Armstrong, K., 2020. Expert opinion on the status and stressors of brook trout, Salvelinus fontinalis, in Ontario. Fisheries Management and Ecology, 27(2), pp.111-122.

Hoxmeier, R.J.H. and Dieterman, D.J., 2020. Demographic responses of brook trout to removal of brown trout from a Driftless Area stream in Minnesota. Final Report STUDY 677.

Huntsman, B.M., Merriam, E.R., Rota, C.T. and Petty, J.T., 2023. Non‐native species limit stream restoration benefits for brook trout. Restoration Ecology, 31(1), p.e13678.

Johnson, A.R., 2022. Anthropogenic Influences on the Decline, Restoration, and Eco-Evolutionary Dynamics of Lake Superior’s Coaster Brook Trout (Doctoral dissertation, Michigan Technological University).

Kazyak, D.C., Lubinski, B.A., Kulp, M.A., Pregler, K.C., Whiteley, A.R., Hallerman, E., Coombs, J.A., Kanno, Y., Rash, J.M., Morgan, R.P. and Habera, J., 2022. Population genetics of Brook Trout in the southern Appalachian Mountains. Transactions of the American Fisheries Society, 151(2), pp.127-149.

Kelly, B., Siepker, M.J. and Weber, M.J., 2021. Factors associated with detection and distribution of native Brook Trout and introduced Brown Trout in the Driftless Area of Iowa. Transactions of the American Fisheries Society, 150(3), pp.388-406.

Kirk, M.A., Rosswog, A.N., Ressel, K.N. and Wissinger, S.A., 2018. Evaluating the trade‐offs between invasion and isolation for native Brook Trout and nonnative Brown Trout in Pennsylvania streams. Transactions of the American Fisheries Society, 147(5), pp.806-817.

Larson, G.L. and Moore, S.E., 1985. Encroachment of exotic rainbow trout into stream populations of native Brook Trout in the southern Appalachian Mountains. Transactions of the American Fisheries Society, 114(2), pp.195-203.

Lehnert, S.J., Baillie, S.M., MacMillan, J., Paterson, I.G., Buhariwalla, C.F., Bradbury, I.R. and Bentzen, P., 2020. Multiple decades of stocking has resulted in limited hatchery introgression in wild Brook Trout (Salvelinus fontinalis) populations of Nova Scotia. Evolutionary Applications, 13(5), pp.1069-1089.

Maitland, B.M. and Latzka, A.W., 2022. Shifting climate conditions affect recruitment in Midwestern stream trout, but depend on seasonal and spatial context. Ecosphere, 13(12), p.e4308.

Manning, M.A., Arismendi, I., Olivos, J.A. and Giannico, G., 2022. Assessing hybridization risk between ESA-listed native Bull Trout (Salvelinus confluentus) and introduced Brook Trout (S. fontinalis) using habitat modeling. Frontiers in Environmental Science, 10, p.126.

Merriam, E.R., Fernandez, R., Petty, J.T. and Zegre, N., 2017. Can Brook Trout survive climate change in large rivers? If it rains. Science of the Total Environment, 607, pp.1225-1236.

Olson, K.W., Pechacek, K. and Benike, H., 2024. Brook Trout population response to Brown Trout removal by electrofishing in a Wisconsin Driftless Area stream. North American Journal of Fisheries Management, 44(3), pp.735-744.

Pechacek, K.J., 2022. Brook Trout (Salvelinus fontinalis) as affected by interspecific competition with non-native Brown Trout (Salmo trutta) following a stream fish community manipulation in the Wisconsin Driftless Area (Master's Thesis). (

Petty, J.T., Thorne, D., Huntsman, B.M. and Mazik, P.M., 2014. The temperature–productivity squeeze: constraints on Brook Trout growth along an Appalachian river continuum. Hydrobiologia, 727, pp.151-166.

Poplar‐Jeffers, I.O., Petty, J.T., Anderson, J.T., Kite, S.J., Strager, M.P. and Fortney, R.H., 2009. Culvert replacement and stream habitat restoration: implications from brook trout management in an Appalachian watershed, USA. Restoration Ecology, 17(3), pp.404-413.

Radinger, J., Essl, F., Hölker, F., Horký, P., Slavík, O. and Wolter, C., 2017. The future distribution of river fish: The complex interplay of climate and land use changes, species dispersal and movement barriers. Global Change Biology, 23(11), pp.4970-4986.

Ridgway, M.S., 2008. A roadmap for coasters: landscapes, life histories, and the conservation of brook trout. Transactions of the American Fisheries Society, 137(4), pp.1179-1191.

Santiago, J.M., Garcia de Jalon, D., Alonso, C., Solana, J., Ribalaygua, J., Pórtoles, J. and Monjo, R., 2016. Brown Trout thermal niche and climate change: Expected changes in the distribution of cold‐water fish in central Spain. Ecohydrology, 9(3), pp.514-528.

Stranko, S.A., Hilderbrand, R.H., Morgan, R.P., Staley, M.W., Becker, A.J., Roseberry-Lincoln, A., Perry, E.S. and Jacobson, P.T., 2008. Brook Trout declines with land cover and temperature changes in Maryland. North American Journal of Fisheries Management, 28(4), pp.1223-1232.

Valerie, O. and Daniels, M.D., 2021. Brook Trout (Salvelinus fontinalis) and Brown Trout (Salmo trutta) summer thermal habitat use in streams with sympatric populations. Journal of Thermal Biology, 98, p.102931.

Vera, M., Aparicio, E., Heras, S., Abras, A., Casanova, A., Roldán, M.I. and García-Marin, J.L., 2023. Regional environmental and climatic concerns on preserving native gene pools of a least concern species: Brown trout lineages in Mediterranean streams. Science of The Total Environment, 862, p.160739.

White, S.L., Miller, W.L., Dowell, S.A., Bartron, M.L. and Wagner, T., 2018. Limited hatchery introgression into wild Brook Trout (Salvelinus fontinalis) populations despite reoccurring stocking. Evolutionary Applications, 11(9), pp.1567-1581.

White, S.L., Rash, J.M. and Kazyak, D.C., 2023. Is now the time? Review of genetic rescue as a conservation tool for brook trout. Ecology and Evolution, 13(5), p.e10142.

Wood, D.M., Welsh, A.B. and Petty, J.T., 2018. Genetic assignment of brook trout reveals rapid success of culvert restoration in headwater streams. North American Journal of Fisheries Management, 38(5), pp.991-1003.