Salmon and Beavers

Research Question

Does the reintroduction of beavers facilitate rehabilitation of freshwater salmon habitats?

Abstract

Throughout the past couple of decades, Beaver have expanded in their native habitats throughout North America, following reduction in trapping and reintroduction efforts. These ecosystem engineers are re-establishing themselves throughout the West, making unexpected alliances and improving various habitats, especially for salmon populations. Throughout this paper my intent is to unveil the misleading misconceptions that beavers are more harmful to stream sh populations than they are beneficial and to provide evidence as to why this relationship is so favorable. I will be doing so by providing contextual evidence from scholarly and peer reviewed articles while also elaborating on previously constructed research using meta-analysis and highlighting expert opinion surveys. Towards the end of this paper, I will also be diving into possible solutions and next steps, including impacts on fly-fishing.

Introduction: The Unforeseen Alliance and Why It Matters
As the last of the snow appeared on the Sawtooth Mountains and the summer winds blew with a hint of crisp autumn air, it was clear the seasons were changing. As I stood along the banks of the Salmon River, I couldn’t help but wonder about the rich salmon that once inhabited this river to its fullest and where they are now. Unfortunately, salmon populations throughout the West have been at a decline for several years, nearing extinction. It wasn’t until recently that researchers came across the idea of acquiring help from an unexpected ally, the American Beaver. Beavers and salmon are two species that have an important relationship in many ecosystems in North America. Within the research that I have done, I have focused on the topics of; the history of both salmon and beaver, the relationship between these two species, the eects of their interactions on each other and their ecosystems, strategies for monitoring and enhancing their survival and touching on next steps to take in the future, specically with outdoor recreation regarding y shing.

Salmon: The History, The People and More
To begin, salmon have been around for thousands of years with a history full of richness and complexity. Before North America had been saturated with early colonization, it had been occupied by indigenous tribes that were originally the keepers of the land. Many people know them as the Nez Perce tribe, but had previously gone by the name of Nimiipuu, meaning The People. As stories were passed down from generation to generation of the time before human beings and when only animals were on the Earth, it is believed that the Chinook Salmon first offered itself to The People to nourish them and keep them alive. Thus the lifetime accountability and bond between the salmon and the Nimiipuu tribe, promising to always protect each other. Over time The People became very accustomed to the chutes and drops on the Columbia and Snake and their tributaries that made from productive shing. The salmon can feed more than 130 species of animals, and their spawned-out bodies bring tons of nutrients back from the sea to the land, in a gyre of life, begetting more life. Before the treaty of 1855, declaring that the Nez Perce must give up their land, the Nimiipuu ate about 81 sh per person each year, acquiring about 50% of their nutrition from the salmon (George, P. 2021). That was when “10 to 16 million salmon returned to the Columbia River every year, including as many as 2 million salmon that swam all the way to the Snake, once the producer of more than 40% of the Chinook in the Columbia Basin” (George, P. 2021). In recent years this hasn’t been the case, with only roughly 1,700 spring and summer salmon returning each year, less than one per tribal member. There are many factors that play into the overall decline of freshwater salmon in North America such as habitat loss and degrading, harvest rates, hatchery inuence, water infrastructure impeding migrations and of course climate change. Because of this there are many law officials trying to reverse some of the damage that has already been done, however, they are going to need some help, perhaps from an unforeseen companion.

Beavers: Perhaps More Useful Than Just For Making Hats
Analogous to the infamous salmon species, throughout the continental United States, lurking in ponds, lakes, rivers and streams you may come across a peculiar animal known as the beaver, Castor Canadensis. Beavers are considered ecosystem engineers, for their ability to drastically alter environments. Their dams allow for an increase in complexity to rivers and streams while slowing the rate of water movement. The ponds behind these dams store water, sediment and increase riparian habitats. Although these significant animals provide a lot of rich benefits to a multitude of ecosystems, their long standing history is somewhat intricate. According to researchers before European settlement, it is estimated that there were between 15 and 250 million beaver ponds that once puddled North America (Goldfarb, Ben. 2018). This of course all changed when beavers were at the heart of the fur trade, quickly declining populations throughout the 1700’s and 1800’s. During this time, their pelts were highly valuable, being used for clothing and hats while their castoreum was used for perfume. This continued until the 1900’s when their numbers had drastically dwindled and had been eradicated from several areas. In areas such as the Rocky Mountain National Park, beavers inhabit only 10 percent of suitable habitat (Reeve, 2016). Because of this, lawmakers decided to restore the drastically low numbers by restricting beaver trapping to specific seasons. Today, beavers ares till rare in certain parts of the Northwest and a significant reason for this is that beavers are considered to be an inconvenience rather than an environmentally essential species. The call to action for restoring beaver populations has become monumentally important. By providing the public with knowledgeable information, perhaps they might change their minds and see beavers for the spectacular ecosystem engineers that they are, with the potential to restore numerous ecosystems.

Relationship Between Salmon and Beavers: The Unexpected Alliance Unveiled
The relationship between salmon and beavers throughout history has been complex and intertwined. For the most part, beavers have been benecial to salmon ecosystems, while salmon have helped sustain the beavers' populations. However, there have been times when these relationships have turned sour, leaving individuals with a negative perception. For example, when beavers began to build dams and divert water away from salmon spawning grounds, the fish populations suffered. Likewise, when human development encroaches on beaver habitats, the animals can become stressed and destructive. Although there have been examples of unfortunate circumstances within this relationship, the benets certainly outweigh them drastically. To begin, there are many ways in which beavers enrich salmon ecosystems through building dams, floodplain connectivity and through various sub-categories such as pond complexes. By beavers cutting down vegetation and building dams, it allows for the ability to alter the rate of water movement of riparian zones ultimately resulting in increased biocomplexity. In addition, beaver dams also provide reduced chances of floods and drought on the salmon’s environment, which in turn helps reduce the impacts of erosion, acting as a barrier (typically temporarily or seasonally) to upstream and downstream movement of sh. It is believed that beavers have the potential to strongly inuence salmon populations in the side channels of large alluvial rivers by building dams that create pond complexes (Malison, Rachel. 2016). Pond habitat may improve salmon productivity or the presence of dams may reduce productivity if dams limit habitat connectivity and inhibit fish passage. However, by creating these ponds, it provides ideal nurseries for juvenile salmon by creating complex edge habitats, increasing the insect and invertebrate food supply, providing healthier clean water, providing slow water refuge allowing sh to conserve energy and aids with winter survival.

In addition, another important fact in beaver-salmon relationships is floodplain connectivity. Floodplains play a critical, if often underappreciated, role in maintaining stream and watershed health. Floodplains are the interface between a river and the land adjacent to it. A connected, functional floodplain attenuates floods and droughts and moderates stream temperatures by retaining water during periods of high flow and releasing it back into the stream when flows are low (TroutUnlimited,2019). Flood plain connectivity is extremely benecial for salmon by providing the salmon with access to areas with optimal spawning conditions, which can help to increase the salmon's population, provides the beavers with more food options and can also help to reduce the impacts of floods and droughts on the salmon's environment, as they can provide an area for the salmon to escape to in times of high water levels. The presence of floodplains can also help to reduce the impacts of erosion on the salmon's habitat, which can help to protect the salmon's population.

Unfortunately however, beaver presence isn’t always available to certain areas or perhaps aren’t always welcomed. This is where Beaver Dam Analogues (BDA’s) come into play. BDA’s are man-made structures designed to mimic a beaver dam. Beaver dam analogues are becoming increasingly popular for salmon restoration projects, as they can provide the salmon with access to areas with ideal spawning conditions without the need to introduce beavers into the environment. Beaver dam analogues increase suitable rearing habitat for juvenile salmonids and promote the restoration of critical stream processes. Installing BDAs is an increasingly popular alternative to more intensive restoration techniques, due to the relatively low cost and eort required to install BDA structures (O’Keefe, Christopher, 2021). When beaver presence isn’t possible, this is also a great option to look into.

Discussion/Methods: Qualitative and Quantitative Effects
Referencing back to the overexploitation of beaver throughout the fur trade, with the help of legislation and reintroduction programs there was a dramatic increase in beaver populations throughout the West.

However, nothing can be done regarding the issue until legislation consults the public concerned, including key stakeholders. When looking at the Eurasian Beaver case study for example, when trying to reintroduce them, the key stakeholders included groups that represented sheries interests. This is extremely important to note, because it has proven to be quite difficult to provide fisheries groups with the information they require on which to base opinion simply due to a clear consensus of impacts of beaver on fish populations is difficult to achieve because of the inherent variability in biological response observed depending on scale, space, time and biotic factors (Kemp, Paul. 2011). Depending on the stakeholder, impacts resulting from the beaver are either viewed as positive or negative, but never consistently the same. Due to these high levels of uncertainty, it has proven to be quite difficult to provide consistent reports on whether beaver reintroduction would be considered benefficial or pernicious specfically on fisheries. This is where the case study “qualitative and quantitative effects of reintroducing beavers on stream fish” comes in handy by providing combined results of expert opinion surveys with systemic meta-analysis of the literature to develop an argument based on the ‘weight of evidence’ for positive or negative impacts of beaver activity on sh populations (Kemp, Paul 2011). The data collected resulted from two search engines ‘Google Scholar’ and ‘Web of Science’. The researchers then used keywords such as ‘European beaver AND Atlantic salmon’, ‘European beaver AND salmon’, ‘European beaver AND trout’, ‘European beaver AND salmonid’, ‘European beaver AND sh’, ‘beaver reintroduction AND fish’, ‘beaver AND reintroduction AND fish’, ‘beaver AND reintroduction AND salmon’, ‘beaver AND impact on fish’ and ‘beaver AND impact on salmon’ to narrow their scope (Kemp, Paul 2011). The research primarily focused on a vote-counting methodology (meta-analysis) that selected statistically significant results that highlighted biases within literature, gaps in understanding and positive and negative effects of beaver interactions or explicit statements that an effect had been detected. Important aspects that were specifically added to the database consisted of region, year of publication, author credentials, beaver and fish species and the believed impacts that beavers impose on fish in general.

Next, the researchers turned their attention towards a questionnaire method. One tool that was used alongside their questionnaire method was a Likert Scale which was used to assess expert opinion of potential impacts of beavers on populations of fish and other ecological/geomorphological processes. The questionnaire contained 28 items. Item 1 had the respondents organized into five different categories (fisheries scientist, geomorphologist, terrestrial ecologist, beaver specialist and other) to describe their profession, the second had them rate their expertise and the third asked which species of fish and beaver they were most familiar with. The rest were based on subjective or objective opinionated questions that the respondents had to answer. The results concluded to 108 articles being surveyed with 95 being primarily based in North America. There was an overwhelming abundance of fish species that were included in the articles so the researchers decided to focus on generic trout, salmonid and all anadromous (fish species that migrate up river from the sea to spawn) species. After the analysis was completed the results concluded that the total number of times that positive impacts were cited was much higher than that of negative. Twenty articles only cited negative impacts versus forty only cited positive (Kemp, Paul. 2011). Another really interesting conclusion that came from this was that over half (51.1%) of the positive impacts were based on data whereas the negative impacts (71.4%) were almost primarily speculative (Kemp, Paul. 2011). Amongst this research, the most commonly addressed positive impacts was ultimately increased abundance and fish productivity paired with increased fish habitat complexity, increased rearing habitat and higher growth rates. Whereas the most common negative impacts concluded in obstacles for fish migration, reduced oxygen concentrations and altered temperature, which have all been shown to not have much effect overall. Within the literature reviewed in this study it has been concluded that, “Both North American and Eurasian beaver influence freshwater ecosystems via their effects on hydrology, geomorphology, water chemistry and temperature. Arguably it is the effects of beaver activity on physical habitat that provides the greatest benefits in enhancing ‘ecological status’ by enabling persistence of a varied riverine habitat mosaic through the creation of lentic patches within a corridor of lotic habitat, ultimately benefiting a multitude of organisms, especially fish” (Kemp, Paul. 2011).

Next Steps: Beavers’ Impact on Fly Fishing and Outdoor Recreation
Moving forward with this project, the next step that I want to take is to analyze the impacts that beavers have on fly fishing. When the idea of reintroducing beavers to salmon habitats arises, there is much debate among fishermen if it is considered beneficial. There have been many claims such as the ponds created from beaver dams result in water being too warm for cold water stream fish, that the dams create too complex of obstacles for fish to be able to migrate and that oxygen will be reduced due to an increased amount of sediment burying eggs.

However, it turns out that water temperatures in the lower depths of beaver ponds are quite cool and water returning to the stream downstream is cooled by the hyporheic effect of underground water flow. So the fish actually have both cold water available for refuge, and warmer water rich in food where they can forage (Beaver Institute, 2018). That being said, salmon and beavers have a powerful and unique relationship that has a lasting impact on outdoor recreation, especially fly fishing. In addition, Redds (a fish nest or a general location selected by the female fish for laying eggs) with oxygen-loving fish eggs can often be found on the downstream sides of beaver dams where sediment is scoured away and the water is higher in precious oxygen after water tumbling over the backside of the beaver dam (Beaver Institute, 2018). This relationship is essential to both species, and has many implications for outdoor activities. Salmon play an important role in the beaver’s diet, and when they are abundant the beaver population thrives. This creates an environment that is ideal for fly fishing, as the beavers create healthy, oxygen-rich waters by building dams. These dams create pools, which allow for better fishing conditions as the pools slow the current, making them easier for fish to navigate. In addition to making fishing easier, the beavers also create habitat for fish by building lodges, which provide protection from predators and a place for fish to spawn. Fly fishing is one of the most popular outdoor activities for sport and recreation, and it relies on a healthy ecosystem. In addition to the relationship between salmon and beavers, beavers play a large role with most stream fish, especially trout and salmon. According to one article that I found based in Idaho, “The big rodents’ dams have also been proven to assist in natural water storage and aquifer replenishment, creating more wet soils that are important to riparian vegetation that, in turn, can grow and shade trout water, providing relief to some of the impacts of a warming climate. ” (Hunt, Chris. 2020). Beavers are, in almost every instance, good for freshwater stream fish.

So far I have not been able to conduct a full survey and do not have enough data to further the discussion with enough evidence, however the methods that I would like to use in the future are highlighting expert opinion surveys, conducting possible questionnaires using polls on social media and perhaps using meta-analysis. The experts that I would ideally like to interview for the questionnaire would be professional anglers (Casting For Recovery, Idaho Angler, Sun Valley Outtters, etc.), Idaho Fish and Game and perhaps corporations such as the Idaho Conservation League. I would then like to ask the following questions, “What level of knowledge would you say you have regarding the information of beavers (low, moderate, high)? Explain.”, “Do you think the reintroduction of beavers may facilitate rehabilitation of freshwater habitats, specically for salmon and trout? (Why/How)?”, “ Would you be willing to pay a little extra on your shing license to go towards reintroducing beavers to these areas and for monitoring beaver-sh interactions? (For example: using aerial surveys, acoustic telemetry, camera trapping or other).”, “Do you think reintroduction of beavers would benet y shing?”, and “Do you think most shermen view beavers as a nuisance or inconvenience?”.

Conclusion: Reflection and Monitoring Ideas
With recent research, it is made clear that beavers ultimately have a more positive inuence on the health of salmon populations. In order to enhance the survival of beavers and salmon, it is important to develop strategies that support their interactions. One strategy is to create beaver dam analogues, which can provide the salmon with access to better areas for spawning. Another strategy is to restore floodplain connectivity, which again can provide the more productive and healthier spawning areas and can also provide the beavers with better food source options. It is also important to monitor beaver-salmon interactions in order to understand the impacts that their interactions are having on the environment and each other. There are a number of strategies that can be used to monitor beaver-salmon interactions, including the use of aerial surveys, acoustic telemetry, and camera trapping. Aerial surveys can be used to monitor the presence of beavers and salmon in an area and to identify areas of high beaver-salmon interaction, Acoustic telemetry can be used to monitor the movements of the beavers and salmon and camera trapping can also be used to monitor the presence of beavers and salmon. In conclusion, there is still much to learn about this unique relationship and the complete impacts they have on each other and their environments. That being said, with the research that has been conducted thus far, it is apparent that this relationship is largely more beneficial than it is not and I would be curious to learn more about not only their relationship, but their impacts on outdoor recreation such as fly fishing as well!

Works Cited

Goldfarb, B., & Flores, D. L. (2018). Eager: The surprising, secret life of beavers and why they matter. Chelsea Green Publishing.

Reeve, H. (2016, August 1). Beaver. Articles | Colorado Encyclopedia. Retrieved March 25, 2023, from https://coloradoencyclopedia.org/article/beaver

Beavers Northwest. (n.d.). About Beavers. Beavers Northwest. Retrieved March 25, 2023, from https://beaversnw.org/about-beavers

Kemper, P. S., Worthington, T., Langford, T., Tree, A., & Gaywood, M. (2011, May 3). Qualitative and quantitative effects of reintroduced Beavers on stream fish. Qualitative and quantitative eects of reintroduced beavers on stream sh. Retrieved March 13, 2023, from https://www.martinezbeavers.org/wp-content/uploads/2018/03/Qualitative-and-quantitative-eects-of-rei ntroduced-beavers-on-stream-sh-METAREVIEW-Kemp-Gaywood-Fish-and-Fisheries-2011.pdf

O'Keefe, C. G. (2021). Do beaver dam analogues act as passage barriers to juvenile coho salmon and juvenile steelhead trout? Digital Commons @ Cal Poly Humboldt. Retrieved March 29, 2023, from https://digitalcommons.humboldt.edu/etd/508/#:~:text=Beaver%20dam%20analogues%20(BDAs)%20incr ease,required%20to%20install%20BDA%20structures.

Floodplain connectivity. Trout Unlimited. (2019, March 8). Retrieved March 29, 2023, from https://www.tu.org/conservation/conservation-areas/watershed-restoration/oodplain-connectivity/#:~:tex t=Floodplains%20are%20the%20interface%20between,stream%20when%20ows%20are%20low.

Why give a damn? - salmon restoration: Beaver Institute, inc.. Beaver Institute, Inc. | Promoting beaver-created wetlands for a healthier planet. (2018, February 15). Retrieved March 30, 2023, from https://www.beaverinstitute.org/why-give-a-damn-salmon-restoration/

Kemp, P. S., Worthington, T. A., Langford, T., Tree, A., & Gaywood, M. J. (2011, May 3). Qualitative and quantitative eects of reintroduced Beavers on stream sh. Retrieved March 30, 2023, from https://www.martinezbeavers.org/wp-content/uploads/2018/03/Qualitative-and-quantitative-eects-of-rei ntroduced-beavers-on-stream-sh-METAREVIEW-Kemp-Gaywood-Fish-and-Fisheries-2011.pdf

Hunt, C. (2020, September 14). Beavers mean bigger trout. Hatch Magazine - Fly Fishing, etc. Retrieved April 18, 2023, from https://www.hatchmag.com/articles/beavers-mean-bigger-trout/7715122

George, P., & Grohman, W. B. (2021, November 4). Columbia River Salmon. CRITFC. Retrieved April 18, 2023, from https://critfc.org/sh-and-watersheds/columbia-river-sh-species/columbia-river-salmon/