Rocky Mountain Sculpin (Cottus sp.), Eastslope Populations: Progress towards the implementation of the recovery strategy for the period 2019 to 2024

Official title: Progress Towards the Implementation of the Recovery Strategy for the Rocky Mountain Sculpin (Cottus sp.), Eastslope Populations, for the Period 2019 to 2024.

Preface

The Species at Risk Act (S.C. 2002, c.29) (SARA) requires the competent minister(s) to monitor and report on the implementation of recovery documents (that is, recovery strategies, action plans, and management plans) for species at risk. These reports must describe the progress made towards the species’ recovery or conservation^{Footnote 1} .

The Minister of Fisheries is the competent minister for aquatic species at risk. Fisheries and Oceans Canada (DFO) has prepared this document.

Reporting on the progress toward implementing recovery documents includes reporting on the collective efforts of the competent minister(s), provincial and territorial governments, and all other parties involved in carrying out actions that contribute to the species’ recovery or conservation.

As stated in the preamble to SARA, success in the recovery and conservation of species at risk depends on the commitment and cooperation of many contributors, and will not be achieved by DFO, or any other jurisdiction, alone. All Canadians are invited to join in supporting and implementing the recovery documents, for the benefit of the species and Canadian society as a whole.

Acknowledgements

The progress report was prepared by regional recovery planners within DFO. The progress toward species recovery described in this report would not have been achieved without the partnerships and contributions of many individuals and organizations.

Executive summary

This report summarizes the progress made by Fisheries and Oceans Canada (DFO) and its partners towards implementing the recovery strategy for the Rocky Mountain Sculpin, Eastslope populations, during the period 2019 to 2024. For more information on the contents of this document, please contact the Species at Risk Program (dfo.ncrsara-leprcn.mpo@dfo-mpo.gc.ca).

1 Rocky Mountain Sculpin (Cottus sp.), Eastslope populations

Fisheries and Oceans Canada (DFO) and its partners have made additional progress towards the implementation of the research and management activities identified in the “Recovery Strategy for the Rocky Mountain Sculpin (Cottus sp.), Eastslope populations, in Canada”, through the actions undertaken between December 2019 and December 2024, to support the recovery of the Rocky Mountain Sculpin, Eastslope populations. The recovery strategy provides detailed information on the species, its threats, its needs, population and distribution objective, the identification of critical habitat, broad strategies, and research and management activities.

This progress report on the implementation of the recovery strategy is part of a series of documents for this species that should be taken into consideration together, including the recovery strategy (DFO 2012) and the first progress report (DFO 2024). The species was considered a single designatable unit (Eastslope populations) and designated threatened in May 2005. The species was reassessed by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) and was split into 2 separate designatable units in November 2019: the “Saskatchewan – Nelson River populations” and “Missouri River populations”, which were both designated threatened (COSEWIC 2019). Within this report, the species is still referred to as “the Eastslope populations” as it is currently (as of 2026) listed under the Species at Risk Act (SARA) and described as such in the recovery strategy. Refer to the Rocky Mountain Sculpin, Eastslope populations species profile on the Species at Risk Public Registry for more information and related documents.

1.1 Progress towards meeting the population and distribution objective for the Rocky Mountain Sculpin, Eastslope populations

Population and distribution objectives establish, to the extent possible, the number of individuals and/or populations, and their geographic areas of distribution, that are necessary for the recovery of the species. The population and distribution objective for the Rocky Mountain Sculpin, Eastslope populations is “to protect and maintain self-sustaining populations of the Rocky Mountain Sculpin within its current range in the St. Mary and Milk river watersheds in Canada.” The key objectives in the recovery strategy are to:

• quantify and maintain current population levels of Rocky Mountain Sculpin in the St. Mary and Milk river watersheds (within the population’s range of natural variation), as determined from a standardized survey program
• increase knowledge of the taxonomy, life history, basic biology, and habitat requirements of the Rocky Mountain Sculpin, with a view towards refining the identification of and protecting critical habitat
• increase our understanding of how human activities affect Rocky Mountain Sculpin survival, so that potential threats to the species can be avoided, eliminated, or mitigated

Four broad strategies were identified in the recovery strategy to meet the population and distribution objective for the Rocky Mountain Sculpin. During the reporting period, recovery actions were undertaken by DFO and its partners under each broad strategy. Some key achievements are described below.

Broad strategy 1: research

• Field research was conducted by DFO and its partners using standardized sampling protocols to study the distribution, relative abundance, and habitat use of the Rocky Mountain Sculpin in St. Mary River, North Milk River and Milk River. Findings are reported on in Barrett et al. (2024)
• The “Conserving Our Threatened Teleosts in the Upper St. Mary” project, led by Freshwater Conservation Canada (FCC) (formerly Trout Unlimited Canada), aimed to restore habitat, improve fish passage, and reduce land use impacts in the Upper St. Mary watershed. In 2023 and 2024, FCC conducted electrofishing to collect baseline data on Rocky Mountain Sculpin in Middle Fork Lee Creek, Lee Creek, and Tough Creek (Ten pers. comm. 2024)
• The “Little Fish, Big Stewardship” project is a collaboration between The Riparian Management Society (Cows and Fish) and Milk River Watershed Council Canada (MRWCC) to improve riparian and in-stream habitat for at-risk fish species in the Milk River watershed. Backpack electrofishing was conducted at 5 tributaries of the North Milk River and Milk River between October and November 2024. Results suggested that fish persisted in spring-fed tributaries of the North Milk River, including periods when the Milk River had low flow due to the structural failure of the St. Mary siphon in June 2024 (MRWCC 2024a)

Broad strategy 2: monitoring

• Rocky Mountain Sculpin in the Milk River watershed were exposed to low water flows due to failures in the St. Mary diversion in May 2020 and the structural failure of the St. Mary siphon in June 2024. DFO and Alberta Environment and Protected Areas (EPA) monitored fish populations in the North Milk River and Milk River
  • In August and October 2020, field sampling suggested that the low summer flows caused by the St. Mary diversion failure did not greatly impact the distribution of Rocky Mountain Sculpin, Eastslope populations. Recorded habitat conditions remained within the range of habitat preferences for the species, as described in section 3.4.2 of the recovery strategy of the Rocky Mountain Sculpin (DFO 2012). Findings are reported on in Teillet et al. (2021)
  • In the fall of 2024, fish sampling confirmed the presence of Rocky Mountain Sculpin in the North Milk River and Milk River during low flow conditions after the structural failure of the St. Mary siphon in June 2024 (Watkinson pers. comm. 2024)
• The study by Barrett et al. (2024) measured habitat use in the St. Mary River watershed and Milk River watershed in 2022
• The MRWCC has monitored the Milk River and some of its tributaries since 2006, focusing on water quality during flow periods (diversion period and natural flow) at 5 sites from 2019 to 2024. Annual reports summarizing these results have been published (MRWCC 2020, 2021, 2022, 2023, 2025)
  • In 2020, MRWCC noted sediment transport and deposition patterns not previously observed, including sediment buildup at the Hoyt Bridge resulting from the failures in the St. Mary diversion and heavy rainfall in late June 2020 (MRWCC 2021)
  • After the structural failure of the St. Mary siphon in June 2024, additional temperature and oxygen monitoring was conducted. Initial data indicated that water temperatures were above the biological limits for fish. Visible adult fish deaths were observed along the Milk River (Romanow pers. comm. 2025)
• As part of the “Conserving Our Threatened Teleosts in the Upper St. Mary” project, FCC assessed the habitat use of Rocky Mountain Sculpin in Middle Folk Lee Creek, Lee Creek, and Tough Creek in 2023 and 2024 (Ten pers. comm. 2024). Results indicated sites with cooler water and slower flow provided ideal habitat conditions for Rocky Mountain Sculpin, while areas with heavy sediment limited their presence. Larger substrates (gravel, cobble, and boulders) were observed to support Rocky Mountain Sculpin presence, particularly in riffle and run habitat where capture rates were higher

Broad strategy 3: management and regulatory actions

• To address ongoing and extended drought and water supply issues in the Milk River, the MRWCC and its partners have developed reports to guide future planning and watershed management. This includes an integrated watershed management plan (MRWCC 2015 ), a summary of past water supply investigations (Palliser Environmental Services Ltd. 2019), and a transboundary state of the watershed report (MRWCC 2024b)
• Temporary diversion licenses, required under Alberta’s Water Act before diverting ground or surface water, are not issued if water levels are too low in the Milk River. The “Alberta Recovery Plan for At-Risk Fish Species in the Milk and St. Mary Rivers” (EPA 2023) aims to improve watershed management by sharing knowledge, working with Indigenous communities, promoting sustainable management practices, and informing stakeholders about current state and future needs of the watershed
• The International Joint Commission’s International St. Mary and Milk Rivers Study is a project to improve water sharing between the United States and Canada. Project updates have been shared through a public webinar (International Joint Commission 2022), a work plan (International Joint Commission 2023a), 2 progress reports (International Joint Commission 2024a , 2024b), and 3 newsletters (International Joint Commission 2023b , 2023c , 2024c)

Broad strategy 4: education and outreach

• Various groups and organizations, including DFO and EPA, have been involved in events and/or developed informational material, including signage and a colouring book, to improve awareness of Rocky Mountain Sculpin, Eastslope populations
• The MRWCC publishes a bi-annual newsletter, “The Meander”, to share information on activities within the Milk River watershed, such as water supply reports, watershed monitoring program results, projects, conservation efforts, and community engagement activities (MRWCC 2024a)
• As part of the “Little Fish, Big Stewardship” project, MRWCC and The Riparian Management Society (Cows and Fish) supported local landowners to implement land management practices that improve riparian and in-stream habitat
• As part of the “Conserving Our Threatened Teleosts in the Upper St. Mary” project, FCC, The Riparian Management Society (Cows and Fish), and grazing leaseholders worked together from 2003 to 2024 on habitat restoration activities, including installing fences to keep livestock out of creeks and riparian areas, and supporting local species recovery efforts (Ten pers. comm. 2024)
• In February 2023, EPA published a recovery plan to establish stakeholder cooperation in restoring at-risk species, those provincially assessed or identified as threatened or endangered under the Alberta’s Wildlife Act, to viable, naturally sustaining populations in the Milk and St. Mary rivers (EPA 2023)
• The Invasive Species Centre implemented measures to protect the Rocky Mountain Sculpin, Eastslope populations, from invasive species from 2019 to 2023. Activities included setting up decontamination stations, conducting outreach in collaboration with MRWCC and EPA, and monitoring for aquatic invasive species
• Between 2019 and 2024, DFO provided $1,968,542 in funding through grants and contributions under the Habitat Stewardship Program and Canada Nature Fund for Aquatic Species at Risk. This supported 3 multispecies and multiyear projects, led by Invasive Species Centre, The Riparian Management Society (Cows and Fish), and FCC that cover Rocky Mountain Sculpin, Eastslope populations in Alberta

The recovery strategy did not include performance indicators. The progress towards achieving the population and distribution objective was informed by the progress made under each broad strategy as described above. There is no evidence to indicate there has been any significant decline in the populations or habitat of Rocky Mountain Sculpin in the St. Mary River basin in Alberta. Ongoing monitoring has been conducted to assess the impact of natural flow condition after the St. Mary siphon failure in June 2024 on the distribution and relative abundance of Rocky Mountain Sculpin in the North Milk River, Milk River, and their tributaries. Additional sampling is planned to assess the fish populations after the siphon restoration. Gaps or work that has not yet started are discussed in the “Key gaps and future priorities” section below.

1.2 Actions supporting the identification of critical habitat

Critical habitat for the Rocky Mountain Sculpin, Eastslope populations, was identified in the recovery strategy to the extent possible, using the best available information. Critical habitat provides the features and attributes necessary to support the species’ life-cycle functions and achievement of the species’ population and distribution objective. Legal protection of critical habitat for the Rocky Mountain Sculpin, Eastslope populations, was achieved on December 4, 2017, through the issuance of a critical habitat order.

The recovery strategy includes a schedule of studies outlining 2 studies that could inform refinement of existing critical habitat or help identify additional critical habitat. Table 1 provides an overview of the status of these studies.

a. Completed: the study has been carried out and concluded
In progress: the planned study is underway and has not concluded.

1.3 Key knowledge gaps and future priorities for the Rocky Mountain Sculpin (Cottus sp.)

The ongoing progress on the recovery activities from 2019 to 2024 has helped further confirm the population distribution and abundance of Rocky Mountain Sculpin, Eastslope populations. These activities have also tracked trends in habitat quality and documented key habitat needs for the species in the St. Mary River and Milk River watersheds. Despite this progress, in the Milk River, Rocky Mountain Sculpin and several other SARA listed aquatic species at risk, have been impacted by low water flows due to failures in the St. Mary diversion in May 2020 and the structural failure of the St. Mary siphon in June 2024. Consequently, there have been ongoing efforts to monitor the changes in relative abundance and distribution of at risk fish species in the North Milk River and Milk River and their tributaries. Collaboration with national and international rightsholders and stakeholders is ongoing to address reduced water flow, which threatens the species’ survival.

Addressing knowledge gaps identified in the recovery strategy remains a priority. Key needs include developing reliable population models, refining life history requirements for early life stage, overwintering requirements, and improving understanding of threats from human activities such as water regulation and land use. The next reporting period will focus on filling these gaps through targeted scientific studies and data collection.

2 Concluding statement

During the reporting period, progress was made toward implementing the research and management activities identified in the recovery strategy for the Rocky Mountain Sculpin, Eastslope populations.

DFO remains committed to the recovery of all aquatic species at risk and the work that has been initiated and completed to date represents an important step in that direction. DFO and its partners will continue to work towards the achievement of the population and distribution objectives for aquatic species at risk, and welcome the participation of additional partners.

3 References

• Barrett, R.T., M. Teillet, D.A. Watkinson, T.A. Rudolfsen, and L.F.G . Gutowsky. 2024. Rocky Mountain Sculpin (Cottus sp.) sampling in the St. Mary and Milk River watersheds, Alberta (2022). Can. Data Rep. Fish. Aquat. Sci. 1389: v + 16 p.
• COSEWIC (Committee on the Status of Endangered Wildlife in Canada). 2019. COSEWIC assessment and status report on the Rocky Mountain Sculpin Cottus sp., Pacific populations, Saskatchewan - Nelson River populations and Missouri River populations in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. xxi +67 p.
• DFO (Fisheries and Oceans Canada). 2012. Recovery Strategy for the Rocky Mountain Sculpin (Cottus sp.), Eastslope populations, in Canada. Species at Risk Act Recovery Strategy Series, Fisheries and Oceans Canada, Ottawa. x + 57 p.
• DFO. 2024. Report on the Progress of Recovery Strategy Implementation for the Rocky Mountain Sculpin, Eastslope populations, (Cottus sp.) in Canada for the Period 2012 to 2019. Species at Risk Act Recovery Strategy Report Series. Fisheries and Oceans Canada, Ottawa. iv+ 21 pp.
• EPA (Alberta Environment and Protected Areas). 2023. Alberta Recovery Plan for At-Risk Fish Species in the Milk and St. Mary Rivers. Alberta Species at Risk Recovery Plan No. 45. Edmonton, AB. 45 pp.
• International Joint Commission. 2022. St. Mary and Milk Rivers Study Work Plan Webinar - Aug. 18, 2022. [accessed October 2024].
• International Joint Commission. 2023a. Work Plan for the International St. Mary and Milk Rivers Study. [accessed April 2025].
• International Joint Commission. 2023b. June 2023 - International St. Mary and Milk Rivers Study Board newsletter, Issue 1 . [accessed October 2025].
• International Joint Commission. 2023c. December 2023 - St. Mary and Milk Rivers Study Board newsletter, Issue 2 . [accessed October 2025].
• International Joint Commission. 2024a. International St. Mary and Milk Rivers Study Board Progress Report - October 6, 2023. [accessed April 2025].
• International Joint Commission. 2024b. International St. Mary and Milk Rivers Study Board Progress Report - September 27, 2024. [accessed April 2025].
• International Joint Commission. 2024c. July 2024 - St. Mary and Milk Rivers Study Board newsletter, Issue 3 . [accessed October 2025].
• MRWCC (Milk River Watershed Council Canada). 2015. Milk River Integrated Watershed Management Plan Final Document. [accessed October 2024].
• MRWCC. 2020. Water Quality Monitoring Report 2019. [accessed October 2024].
• MRWCC. 2021. Water Quality Monitoring Report 2020. [accessed October 2024].
• MRWCC. 2022. Water Quality Monitoring Report 2021. [accessed October 2024].
• MRWCC. 2023. Water Quality Monitoring Report 2022. [accessed October 2024].
• MRWCC. 2024a. The Meander Fall/Winter 2024. [accessed January 2025].
• MRWCC. 2024b. Milk River Transboundary State of the Watershed Report 3rd Edition. Prepared by Palliser Environmental Services Ltd. for the Milk River Watershed Council Canada (Alberta) and the South of the Divide Conservation Action Program, Inc. (Saskatchewan), Milk River, Alberta. 341 pp.
• MRWCC. 2025. Water Quality Monitoring Report 2023 and 2024. [accessed March 2025].
• Palliser Environmental Services Ltd. 2019. Summary of Past Water Supply Investigations in the Milk River Basin, Alberta. Prepared for the Milk River Watershed Council Canada, Milk River, AB. 24 p + Appendix.
• Romanow, T., pers. comm. 2025. Email correspondence to Zing-Ying Ho. October 2025. Executive Director, Milk River Watershed Council Canada, Milk River, Alberta.
• Teillet, M., D.A. Watkinson, S.F. Petry, and E.C. Enders. 2021. Report on Plains Sucker (Pantosteus jordani), Rocky Mountain Sculpin (Cottus sp.), Western Silvery Minnow (Hybognathus argyritis), and Stonecat (Noturus flavus) sampling conducted in 2020 in the Milk River drainage, Alberta. Can. Data Rep. Fish. Aquat. Sci. 1330: vi + 13 p.
• Ten, A., pers. comm. 2024. Email correspondence to Folarin Solademi. December 2024. Management Biologist, Freshwater Conservation Canada, Calgary, Alberta.
• Watkinson, D.A., pers. comm. 2024. Email correspondence to Folarin Solademi. December 2024. Research Biologist, Fisheries and Oceans Canada, Winnipeg, Manitoba.