Tag Archives: Bull Trout

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!

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!

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.

Abstract:

Freshwater biodiversity is declining from impacts associated with anthropogenic stressors. Here, we use carbon (δ13C) and nitrogen (δ15N) stable isotopes to assess food web effects following a coal mine spill that displaced biota and altered biophysical stream characteristics. We compared isotopic niche metrics of benthic macroinvertebrates and the fish community, including non-native brook trout (Salvelinus fontinalis) and endangered Athabasca rainbow trout (Oncorhynchus mykiss), to infer spatial differences in site-specific resource use along a habitat disturbance gradient. Predatory benthic macroinvertebrate trophic position was elevated where impacts from the spill were most pronounced. Autochthonous carbon contribution to consumer diets was lowest in biota sampled at the most highly impacted site from the mine spill, leading to an unexpected expansion of the isotopic niche size of rainbow trout and the aquatic invertebrate community. Collectively, our results suggest spatial variation in trophic resource assimilation across multiple levels of the food web, fuelled by the allochthonous energy pathway in highly impacted study sites. We conclude this reflects a biotic response to altered basal aquatic resources following a major industrial disturbance.

Citation: 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.

Also Read:

Nelson-Chorney, H.*, Carli, C.M., Davis, C.S., Vinebrooke, R.D., Poesch, M.S., and M.K. Taylor (2019) Environmental DNA in lake sediment reveals biogeography of native genetic diversity. Frontiers in Ecology and Evolution 17: 313-318.

*Lab members: Nathan Medinski, Bryan Maitland, Mark Poesch. Check out opportunities in the lab!

Nelson-Chorney, H.*, Carli, C.M., Davis, C.S., Vinebrooke, R.D., Poesch, M.S., and M.K. Taylor (2019) Environmental DNA in lake sediment reveals biogeography of native genetic diversity. Frontiers in Ecology and Evolution 17: 313-318.

Abstract: 

Understanding the historical distributions of species is vital to the conservation and restoration of native species, yet such information is often qualitative. We show that the paleolimnological history of threatened freshwater fishes can be reconstructed using species‐diagnostic markers amplified from environmental DNA deposited in lake sediments (lake sedDNA). This method was validated through the detection of lake sedDNA from non‐native trout (Yellowstone cutthroat trout, Oncorhynchus clarkii bouvieri), which corroborated historical records of human‐mediated introductions. We also discovered native trout (westslope cutthroat trout, Oncorhynchus clarkii lewisi) lake sedDNA that predated human‐mediated introductions of freshwater fishes in a watershed with high topographical relief. This unexpected result revealed that the westslope population was of native origin and requires immediate conservation protection. Our findings demonstrate that lake sedDNA can be used to determine the colonization history of freshwater fishes and the structure of ecosystems, aiding in the identification of native ranges, novel native diversity, and introductions of non‐native species. 

Citation: Nelson-Chorney, H., Carli, C.M., Davis, C.S., Vinebrooke, R.D., Poesch, M.S., and M.K. Taylor (2019) Environmental DNA in lake sediment reveals biogeography of native genetic diversity. Frontiers in Ecology and Evolution 17: 313-318.

Also Read: 

Poesch, M.S., Chavarie, L., Chu, C., Pandit, S.N.*, and W. Tonn. (2016) Climate change impacts on freshwater fishes: A Canadian perspective. Fisheries 41(7): 385-391.

*Lab members:   Hedin Nelson-Chorney, Mark Poesch. Check out opportunities in the lab!

Lamothe,K.A., Drake, D.A.R., Pitcher, T.E., Broome, J.E., Dextrase, A.J., Gillespie, A., Mandrak, N.E., Poesch, M.S., Reid, S.M. and N. Vachon. (2019) Reintroduction of fishes in Canada: a review of research progress for SARA-listed species. Environmental Reviews 27(4): 575-599.

Abstract:

Fishes are among the most threatened taxa in Canada with over 70 species, subspecies, and/or Designatable Units presently listed for protection under the Species at Risk Act (SARA). Protecting these species requires a diverse set of strategies based on the best-available data and information. One strategy identified in Canadian federal recovery strategies for improving the status of SARA-listed fishes is species reintroduction, which involves the release of individuals into areas from which they have been extirpated with the goal of re-establishing self-sustaining populations. The success of reintroduction relies on a comprehensive understanding of species life history and ecology, with considerations around population genetics and genomics. However, SARA-listed species are some of the most poorly known species in Canada due to their rarity and relative lack of research investment prior to the enactment of SARA. As a result, SARA-listed species have the most to lose if reintroduction activities are not carefully researched, planned, and executed. Therefore, the purpose of this review is to present an accessible summary on the state of reintroduction science for SARA-listed fishes in Canada with the hope of motivating future research to support reintroduction activities. We focus our review on 14 SARA-listed freshwater or anadromous fishes identified as candidates for reintroduction in federal recovery strategies. We follow our species-specific summaries with guidance on how basic research questions in population ecology, habitat science, and threat science provide a critical foundation for addressing knowledge gaps in reintroduction science. Subsequently, we identify the importance of genetic and genomic techniques for informing future research on the reintroduction of SARA-listed species. We conclude with recommendations for active, experimental approaches for moving reintroduction efforts forward for recovering Canadian fishes.

Voted as Editor’s Choice for 2019!

Citation: Lamothe,K.A., Drake, D.A.R., Pitcher, T.E., Broome, J.E., Dextrase, A.J., Gillespie, A., Mandrak, N.E., Poesch, M.S., Reid, S.M. and N. Vachon. (2019) Reintroduction of fishes in Canada: a review of research progress for SARA-listed species. Environmental Reviews 27(4): 575-599.

Also Read:

Castaneda, R.A., Ackerman, J.D., Chapman, L.J., Cooke, S.J., Cuddington, K., Dextrase, A., Jackson, D.A., Koops, M.A., Krkosek, M., Loftus, K., Mandrak, N.E., Martel, A.L., Molnar, P., Morris, T.J., Pitcher, T.E., Poesch, M.S., Power, M., Pratt, T.C., Reid, S.M., Rodriguez, M.A., Rosenfeld, J., Wilson, C., Zanatta, D.T. and D.A.R. Drake. (2021) Approaches and research needs for advancing the protection and recovery of imperilled freshwater fishes and mussels in Canada. Canadian Journal of Fisheries and Aquatic Sciences 78 (9): 1356-1370.

Maitland, B.M.*, M.S. Poesch, Anderson, A.E., and S. Pandit*. (2016) Industrial road crossings drive changes in community structure and instream habitat for freshwater fishes in the Boreal forest. Freshwater Biology. 61: 1-18.

Abstract:

Stream crossing structures are an increasingly prevalent anthropogenic feature on North American riverscapes, particularly in watersheds affected by industrial resource development in sensitive boreal environments. If improperly managed, stream crossings have the potential to alter fish habitat and impede fish movement. This study assessed instream habitat characteristics and fish communities from 33 culverted, bridged and reference streams in an industrialising region of the boreal forest in west-central Alberta. Mixed-effects modelling and multivariate analysis were used to determine impacts of stream crossings at three scales: whole-stream scale, within-stream scale and the interaction of scales. Instream habitat characteristics such as mean depth, water velocity, percent fines, turbidity, water temperature and dissolved oxygen showed significant between-stream as well as within-stream differences among stream crossings. The majority of fish species exhibited significantly lower densities (n m−2) in upstream habitats as compared to downstream habitats, including a significant reduction in Slimy Sculpin densities in culverted streams. Multivariate tests corroborated these results, showing that fish assemblages differ as a function of stream type. This study suggests industrial stream crossings influence abiotic habitat characteristics in freshwater ecosystems, restrict biotic connectivity and impact fish community structure at the whole-stream and within-stream scales. Alterations to stream ecosystems associated with stream crossings may be driving large-scale changes in stream fish communities in the boreal forest. With expanded development expected in much of North America’s boreal region, mitigation measures which limit impacts from stream crossings are needed to ensure proper ecosystem function in freshwater systems.

Citation: Maitland, B.M.*, M.S. Poesch, Anderson, A.E., and S. Pandit*. (2016) Industrial road crossings drive changes in community structure and instream habitat for freshwater fishes in the Boreal forest. Freshwater Biology. 61: 1-18.

Figure – Barplot of fish community metrics of (a) fish density (number per m2) and (b) species richness across stream types and upstream and downstream locations (mean +/- SE). Sample sizes for stream types were: culvert (Cul) N = 11, bridge (Bri) N = 11, reference (Ref) = 11. Significant differences across stream types are identified by upper case letters, while significant differences between upstream and downstream reaches are identified by lower case letters.

Also Read:

Fischer, S.M.*, Ramaza, P., Simmons, S., Poesch, M.S. and M.A. Lewis. (2023) Boosting propagule transport models with individual-specific data from mobile apps. Journal of Applied Ecology 60(5): 934-949.

*Lab members: Bryan Maitland, Shubha Pandit, Mark Poesch. Check out opportunities in the lab!

Maitland, B.M.*, Anderson, A. and Poesch, M.S. (2016) Prioritising culvert removals to restore habitat for at-risk salmonids in the Boreal forest. Fisheries Management and Ecology 23: 489-502.

Abstract:

Stream crossing structures are an increasingly prevalent anthropogenic feature on North American riverscapes, particularly in watersheds affected by industrial resource development in sensitive boreal environments. If improperly managed, stream crossings have the potential to alter fish habitat and impede fish movement. This study assessed instream habitat characteristics and fish communities from 33 culverted, bridged and reference streams in an industrialising region of the boreal forest in west-central Alberta. Mixed-effects modelling and multivariate analysis were used to determine impacts of stream crossings at three scales: whole-stream scale, within-stream scale and the interaction of scales. Instream habitat characteristics such as mean depth, water velocity, percent fines, turbidity, water temperature and dissolved oxygen showed significant between-stream as well as within-stream differences among stream crossings. The majority of fish species exhibited significantly lower densities (n m−2) in upstream habitats as compared to downstream habitats, including a significant reduction in Slimy Sculpin densities in culverted streams. Multivariate tests corroborated these results, showing that fish assemblages differ as a function of stream type. This study suggests industrial stream crossings influence abiotic habitat characteristics in freshwater ecosystems, restrict biotic connectivity and impact fish community structure at the whole-stream and within-stream scales. Alterations to stream ecosystems associated with stream crossings may be driving large-scale changes in stream fish communities in the boreal forest. With expanded development expected in much of North America’s boreal region, mitigation measures which limit impacts from stream crossings are needed to ensure proper ecosystem function in freshwater systems.

Citation: Maitland, B.M.*, Anderson, A. and Poesch, M.S. (2016) Prioritising culvert removals to restore habitat for at-risk salmonids in the Boreal forest. Fisheries Management and Ecology 23: 489-502.

Site Locations of Assessed Stream Crossings, including (a) Simoneete, (b) Latronell and (c) Deep Valley watersheds in Alberta Canada.

Prioritization given: net habitat gain (a,d), number of barriers removed (c,f) and the mean cost per barrier (c,f) across Deep Valley and Latronell subwatersheds.

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: Bryan Maitland, Mark Poesch. Check out opportunities in the lab!

Poesch, M.S., Chavarie, L., Chu, C., Pandit, S.N.*, and W. Tonn. (2016) Climate change impacts on freshwater fishes: A Canadian perspective. Fisheries 41(7): 385-391.

Abstract:

Current and projected patterns of global climate change are a major concern to freshwater fisheries in Canada. The magnitude of the impacts of climate change vary among species and ecoregions. The latest climate change scenario projections for Canada suggest that by 2050 temperatures will increase between about 4.9°C ± 1.7°C (average mean ± standard deviation) and 6.6°C ± 2.3°C under the Representative Concentration Pathways (RCPs) 2.6 and 8.5 emission scenarios, respectively. These changes will have an important influence on the physiology, distribution, and survival of freshwater fishes, as well as other ecological processes in direct, indirect, and complex ways. Here we provide a perspective from the Canadian Aquatic Resources Section on the impacts of climate change to freshwater fishes. Given the geographic size and diversity of landscapes within Canada, we have divided our perspective into three regions: eastern, western, and northern Canada. We outline the impacts of climate change to these regions and outline challenges for fisheries managers. Because climate change does not operate in isolation of other environmental threats, nor does it impact species in isolation, we suggest improved inter jurisdictional integration and the use of an adaptive and ecosystem-based approach to management of these threats.

Citation: Poesch, M.S., Chavarie, L., Chu, C., Pandit, S.N.*, and W. Tonn. (2016) Climate change impacts on freshwater fishes: A Canadian perspective. Fisheries 41(7): 385-391.

List of species that have potential to extend their range and/or abundance northward into the Arctic, with some biological characteristics related to expansion of their existing ranges.

Also Read:

Theis, S.*  Castellanos D.A., Hamann A. and M.S. Poesch. (2022) Exploring the potential role of habitat banks in preserving freshwater biodiversity and imperiled species in the United States. Biological Conservation 273: 109700.

*Lab members: Shubha Pandit, Mark Poesch. Check out opportunities in the lab!

Scott, R.J., Poesch, M.S., Noakes, D.L.G., and F.W.H. Beamish (2005) Effects of exotic salmonids on juvenile Atlantic salmon behavior. Ecology of Freshwater Fish 14: 283-288.

Abstract:

We examined the effects of two salmonid species, chinook salmon (Oncorhynchus tschwaytscha) and brown trout (Salmo trutta), both exotic species to Lake Ontario, on behaviour and foraging success of juvenile Atlantic salmon (S. salar), a native species to Lake Ontario, in an artificial stream. We found that both exotic species have effects on Atlantic salmon behaviour, but that neither had an effect on foraging success. These results may explain why the Atlantic salmon re-introduction programme in Lake Ontario has had little success, as more than 3 million exotic salmonids are released in Lake Ontario streams annually.

Citation: Scott, R.J., Poesch, M.S., Noakes, D.L.G., & Beamish, F.W.H. 2005. Effects of exotic salmonids on juvenile Atlantic salmon behavior. Ecology of Freshwater Fish 14: 283-288.

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.