Category Archives: Conservation of Freshwater Fishes

Freshwater fishes are among the most imperiled groups globally with rates of decline comparable to declines in tropical rainforest species. Research in the PoeschLab focuses on developing a better understanding of the mechanisms for the decline of freshwater organisms. This research has four main themes, including: 1) threats to freshwater species at risk, 2) stream augmentation and hydrologic alteration, 3) climate change impacts to freshwater fishes, and 4) the spread and impact of invasive species. To achieve our research goals we utilize a variety of expertise in the PoeschLab and the University of Alberta. This includes expertise in: movement ecology and telemetry, assessing foodwebs using stable isotope analysis, population genetics and environmental DNA (eDNA) and morphology and swim performance.

Veillard, M., Watkinson, D. and M. S. Poesch. (2026). Biotic and abiotic factors and their interaction influence the seasonal movement patterns of a dispersal limited benthic species. Environmental Biology of Fishes 109:86.

Abstract:

Dispersal is an important mechanism linked with population viability. Increases in species-specific dispersal allow for improved connectivity between habitat patches and populations. Here, we seek to understand the role of both biotic and abiotic factors, and their interactions, in influencing the movement of the recently identified and federally threatened Rocky Mountain sculpin (Cottus sp.). We conducted a mark-recapture study in a 400 m reach of Lee Creek in Alberta, Canada, using passive integrated transponder and visible implant elastomer tags across approximately 4 months. Boosted regression tree models were used to assess the movement of (1) all recaptured individuals (global model) and (2) only mobile individuals (movement only model) in response to abiotic and biotic factors. Biotic factors, such as congeners at the destination (8.7%), congeners at the origin (8.0%), and competitors at the origin (7.2%) were the most important variables for predicting movement in the global model. Alternatively, cobble (18.7%) followed by biotic factors including congeners at the origin (9.6%) and competitors at the origin (9.1%) were the most important variables selected in the movement only model. Biotic and abiotic factors showed strong interactions, providing a clear example of the importance of competition in the understanding of movement. Although the vast majority of restoration activities for endangered species are aimed at abiotic (i.e. habitat-related) factors, this study shows how these may be limited without considering biotic interactions, such as the role of inter- and intraspecific competition.

Citation: Veillard, M., Watkinson, D. and M. S. Poesch. (2026). Biotic and abiotic factors and their interaction influence the seasonal movement patterns of a dispersal limited benthic species. Environmental Biology of Fishes 109:86. DOI: https://doi.org/10.1007/s10641-026-01841-9

Also Read:

Medinski, N.A.*, Maitland, B.M.*, Jardine, T.D., Drake, D.A.R. and M.S. Poesch (2022) A catastrophic coal mine spill in the Athabasca River watershed induces isotopic niche shifts in stream biota including an endangered rainbow trout ecotype. Canadian Journal for Fisheries and Aquatic Sciences 79(8): 1321-1334.

*Lab members: Marie Veillard and Mark Poesch. Check out opportunities in the lab!

Pallard J., Jardine, T. and M. S. Poesch. (In Press) Altered resource use by threaten Bull Trout (Salvelinus confluentus) amid competition from two non-native salmonids. Journal of Fish Biology.

Abstract

  1. Introduction of non-native species contributes to the global decline of freshwater fishes by disrupting the diet and resources of native species through competition. Despite potential for non-native trout (Family: Salmonidae) to compete with native trout, non-native trout species have been widely introduced worldwide to support recreational fishing.
  2. In this study, we examined resource use by native Bull Trout (Salvelinus confluentus), a Threatened species, and non-native Brook Trout (Salvelinus fontinalis) and Brown Trout (Salmo trutta) in headwater streams in Alberta, Canada. Our objective was to investigate potential for competition and its implications for Bull Trout populations. To assess changes in diet, we used stable isotope analysis.
  3. Brook Trout and Brown Trout had higher trophic positions (3.49 ± 0.02 and 3.53 ± 0.02) and greater proportions of terrestrial resources in their diets (0.53 ± 0.02, 0.54 ± 0.03) than Bull Trout (TP = 3.38 ± 0.02, proportion terrestrial = 0.36 ± 0.02) suggesting the non-native species may outcompete Bull Trout for preferred resources and larger prey. Moreover, a relatively wide isotopic niche of Bull Trout led to a lack of niche partitioning and substantial overlap in niche utilization between sympatric Brook Trout and Bull Trout, supporting the potential for future niche displacement, particularly in scenarios where resources are scarce.
  4. These findings underscore the importance of monitoring and managing the invasion of non-native salmonids in streams where native salmonid populations exist, and the challenges in understanding multi-species interactions in dynamic habitats. It highlights the need for effective fisheries management and conservation efforts in regions where native freshwater fishes are facing population declines.

Citation: Pallard J., Jardine, T. and S. Poesch. (In Press) Altered resource use by threaten Bull Trout (Salvelinus confluentus) amid competition from two non-native salmonids. Journal of Fish Biology.

Also Read:

Medinski, N.A.*, Maitland, B.M.*, Jardine, T.D., Drake, D.A.R. and M.S. Poesch (2022) A catastrophic coal mine spill in the Athabasca River watershed induces isotopic niche shifts in stream biota including an endangered rainbow trout ecotype. Canadian Journal for Fisheries and Aquatic Sciences 79(8): 1321-1334.

*Lab members: Jacquie Pallard and Mark Poesch. Check out opportunities in the lab!

Schmid J., Simmons S., Lewis M., Poesch, M. S. and R. Pouria. (2026) Website visits can predict angler presence using machine learning. FACETS 11:1-10.

Abstract:
Understanding and predicting recreational angler effort is important for sustainable fisheries management. However, conventional methods of measuring angler effort, such as surveys, can be costly and limited in both time and spatial extent. Models that predict angler effort based on environmental or economic factors typically rely on revealed data (past observed behavior), which often limits their spatial and temporal generizability due to data scarcity. In this study, high-resolution data from an online fishing platform and easily accessible auxiliary data were tested to predict daily boat presence and aerial counts of boats at almost 200 lakes over 5 years in Ontario, Canada. Lake-information website visits alone enabled predicting daily angler boat presence with 78% accuracy. While incorporating additional environmental, socio-ecological, weather, and angler-reported features into machine learning models did not remarkably improve prediction performance of boat presence, they were substantial for the prediction of boat counts. Models achieved an R2 of up to 0.77 at known lakes included in the model training, but they performed poorly for unknown lakes (R2 = 0.21). The results demonstrate the value of integrating data from online fishing platforms into predictive models and highlight the potential of machine learning models to enhance fisheries management.

Citation: Schmid J., Simmons S., Lewis M., Poesch, M. S. and R. Pouria. (2026) Website visits can predict angler presence using machine learning. FACETS 11: 1-10.

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Also Read:

Schmid J., Simmons S., Poesch M. S., Ramazi P. and M. Lewis. (2025) Analyzing fisher effort – Gender differences and the impact of Covid-19. Canadian Journal of Fisheries and Aquatic Sciences.

*Lab members: Julia Schmid and Mark Poesch. Check out opportunities in the lab!

Tierney K. B., Smith J., Veillard M., Steffler M. V. and M. S. Poesch. (2025). Subpopulations of an imperilled freshwater fish shows behavioral adaptation that informs survival in the Anthropocene. Canadian Journal of Fisheries and Aquatic Science 82:1-10.

Abstract:

Freshwater fishes are amongst the most threatened group of animals. Changes in river flows are an important driver in this. To gauge the ability of a common freshwater fish to respond to altered flows, we examined how sculpins from rivers with different flow regimes behaviourally responded to increasing water speeds. We chose the imperiled Rocky Mountain Sculpin, since within their restricted geographic distribution, there are endemic subpopulations that inhabit rivers with high and low flow volumes, and an introduced subpopulation that inhabits a river with moderate flow volume. Sculpins were collected from these rivers, acclimated to laboratory conditions, and their swimming behaviour was observed in a three-chambered flume. Swimming activity did not differ between the subpopulations, but stream place preference did: sculpins from high flow volume preferred upstream, while sculpins from moderate flow volume preferred downstream, and sculpins from low flow volume were indifferent. An exploratory phenotype was present in each subpopulation. This study suggests that altered river flows may change upstream and downstream place preference, which in turn could affect species distributions and interactions.

Citation: Tierney K. B., Smith J., Veillard M., Steffler M. V. and M. S. Poesch. (2025). Subpopulations of an imperilled freshwater fish shows behavioral adaptation that informs survival in the Anthropocene. Canadian Journal of Fisheries and Aquatic Science 82:1-10.

Also Read:

Medinski, N.A.*, Maitland, B.M.*, Jardine, T.D., Drake, D.A.R. and M.S. Poesch (2022) A catastrophic coal mine spill in the Athabasca River watershed induces isotopic niche shifts in stream biota including an endangered rainbow trout ecotype. Canadian Journal for Fisheries and Aquatic Sciences 79(8): 1321-1334.

*Lab members: Marie Veillard and Mark Poesch. Check out opportunities in the lab!

Pallard J. and M. S. Poesch. (2025) Factors affecting Bull Trout (Salvelinus confluentus) abundance and potential displacement by non-native Brook Trout (Salvelinus fontinalis) and Brown Trout (Salmo trutta) in headwater streams. Aquatic Conservation: Marine and Freshwater Ecosystems 35(9): e70227.

Abstract

The invasion of non-native fish species poses a major threat to native salmonids in freshwater ecosystems. We investigated the potential displacement of threatened Bull Trout (Salvelinus confluentus) by non-native Brook Trout (Salvelinus fontinalis) and Brown Trout (Salmo trutta) in 44 headwater streams across Alberta, Canada. Using electrofishing surveys and a combination of single- and multi-species N-mixture models, we examined how fish abundance responds to instream habitat characteristics, landscape features, and species interactions, while accounting for imperfect detection. Results revealed that reduced Bull Trout abundance was correlated with the abundance of Brook Trout in cold streams (mean August temperature <11°C) that lack habitat complexity, particularly where large woody debris and heterogeneous channel features are limited. Conversely, Brown Trout were associated with reduced Bull Trout abundance in larger, lower-elevation systems, likely due to competitive dominance in deeper and slower habitats. These findings highlight that temperature alone likely does not dictate displacement risk; and that habitat structure and species-specific traits also play critical roles. Management strategies should prioritize the protection of cold, structurally complex streams and consider targeted removals or exclusion strategies to limit further invasion. Habitat restoration and assisted colonization to suitable, non-invaded refugia may further enhance Bull Trout conservation under ongoing climate and land-use change.

Citation: Pallard J. and M. S. Poesch. (2025) Factors affecting Bull Trout (Salvelinus confluentus) abundance and potential displacement by non-native Brook Trout (Salvelinus fontinalis) and Brown Trout (Salmo trutta) in headwater streams. Aquatic Conservation: Marine and Freshwater Ecosystems 35(9): e70227. DOI: 10.1002/aqc.70227.

Also Read:

Medinski, N.A.*, Maitland, B.M.*, Jardine, T.D., Drake, D.A.R. and M.S. Poesch (2022) A catastrophic coal mine spill in the Athabasca River watershed induces isotopic niche shifts in stream biota including an endangered rainbow trout ecotype. Canadian Journal for Fisheries and Aquatic Sciences 79(8): 1321-1334.

*Lab members: Jacquie Pallard and Mark Poesch. Check out opportunities in the lab!

Edgar M., Kimmel, N. and M. S. Poesch. (2025) Community trophic structure within reservoirs change in the presence of invasive Chinese Mystery Snail (Cipangopaludina chinensis) and Northern Crayfish (Faxonius virilis). Aquatic Science 87: 99.

Abstract

The expansion of invasive species significantly threatens ecosystem biodiversity and stability, often leading to alterations in food web dynamics and trophic interactions. This study examines the impacts of two invasive species, the Chinese Mystery Snail (Cipangopaludina chinensis) and Northern Crayfish (Faxonius virilis), in Alberta’s reservoir ecosystems. These species, originally from Asia and Canada’s eastern regions respectively, have established populations in Alberta, raising concerns about their effects on local aquatic food webs. Using stable isotope analysis across five reservoirs with varying invasive species presence, we assessed shifts in trophic structure, resource use, and isotopic niche overlap among native and invasive species. Findings reveal that reservoirs with invasive species showed significant changes in food web length, trophic diversity, and isotopic niche overlap, especially in systems where both species coexisted. Notably, both invasive species reduced macrophyte availability, or availability of isotopically similar resources, leading to shifts in fish diets toward higher trophic levels and affecting their trophic positions. Additionally, niche overlap between the two invasives suggests potential competition for resources, with Northern Crayfish possibly predating on Chinese Mystery Snail in resource-scarce environments. These results indicate that invasive species presence can significantly impact trophic structures, leading to competitive exclusion, changes in fish feeding strategies, and broader ecosystem productivity alterations. Future management should prioritize containment and monitor these invasives’ long-term impacts, particularly given their potential to disrupt biodiversity and ecosystem function.

Citation: Edgar M.*, Kimmel, N. and M. S. Poesch. (2025) Community trophic structure within reservoirs change in the presence of invasive Chinese Mystery Snail (Cipangopaludina chinensis) and Northern Crayfish (Faxonius virilis). Aquatic Sciences 87: 99. DOI: 10.1007/s00027-025-01220-z.

Also Read:

Edgar M.*, Hanington P., Lu R., Proctor H., Zurawell R., Kimmel N. and M.S. Poesch (2022) The First Documented Occurrence and Life History Characteristics of the Chinese Mystery Snail (Cipangopaludina chinensis, Mollusca: Viviparidae) in Alberta, Canada. BioInvasions Records 11(2): 449-460.

*Lab members: Megan Edgar and Mark Poesch. Check out opportunities in the lab!

Congratulations to Jessica Serbu, Vince St. Louis and team for being named ‘Most Viewed’ on our article on climate change (see info)!

Jessica’s paper develops a comprehensive overview of glaciers by the Rocky Mountains.

Citation: Serbu, J. A., St. Louis, V. L., Emmerton, C. A., Tank S., Criscitello, A., Silins, U., Bhatia, M., Cavaco, M., Christenson, C., Cooke, C., Drapeau, H., Enns, S. J., Flett, J., Holland, K., Lavelle-Whiffen, J., Ma, M., Muir, C., Poesch, M. S., and J. Shin. (2023). A comprehensive biogeochemical assessment of climate-threatened glacial river headwaters on the eastern slopes of the Canadian Rocky Mountains. JGR Biogeosciences 129: e2023JG007745.