Freshwater mussels (family Unionidae and Margaritiferidae) are bivalves that live at the bottom of lakes, streams, and wetlands across the United States. They have an interesting life cycle where larval mussels (glochidia) must go through a parasitic stage on a specific fish host (Haag 2012). They filter water for their food (e.g., algae, bacteria), and in the process, they help cycle nutrients and improve water clarity. They also provide habitat for other animals (e.g., crayfish and small fish hide in empty freshwater mussel shells), and are a source of food for many animals (Haag 2012; Williams et al. 2014). Freshwater mussels are sensitive to anthropogenic impacts, and are therefore considered indicators of healthy aquatic environments. Unfortunately, this sensitivity contributes to a high rate of imperilment, and they are among the most imperiled group of animals in North America (Haag and Williams 2014). There are two species of native freshwater mussel in Utah, Winged Floater and Western Pearlshell, and both are listed as Species of Greatest Conservation Need (SGCN) in the Utah Wildlife Action Plan (UWAP; UWAP 2015 and 2020 minor amendment). Both species are found in neighboring states, and range-wide, both species are considered imperiled. Winged Floater are considered vulnerable and Western Pearlshell are considered near threatened due to decreased watershed area occupied, decreased extent of occurrence, and reports of declining populations since 1990 (Blevins et al. 2017). In Utah, many of the historical localities for these freshwater mussels were visited by UDWR biologists in recent years (2018-2021; ESMF project numbers 23, 62, 126 and 187), but these surveys were not exhaustive. New localities for these freshwater mussels are still being found, and more area needs to be surveyed to better understand their current distribution, status, and threats. It will be important to implement this project by FY23 so that the findings can be used to update s-ranks for the revised UWAP in 2025. Results of this project may suggest that the two SGCN freshwater mussels are more stable than previously thought, leading to a higher (better) s-rank and possible removal from the SGCN list. Conversely, this study may find that they are more imperiled than previously thought. Either outcome will allow UDWR to better understand the current status of the two freshwater mussel species and move forward with appropriate conservation actions. Implementing this project, along with proposed ESMF project #6110 (Host Fish Identification for Utah Freshwater Mussels), will help UDWR ensure sport fish management benefits freshwater mussels. Since freshwater mussels require specific fish hosts to complete their life cycle, fish management can directly affect the persistence of freshwater mussels. If the freshwater mussel's fish hosts are not present, they cannot reproduce, and their population will eventually die out. UDWR sport fish management can ensure that the appropriate host fish are present, and can focus on supporting fisheries the benefit both freshwater mussels and anglers. Implementing this project will help UDWR understand where our strong and weak mussel populations are located, and implementing project #6110 will confirm which fish hosts our freshwater mussels need for successful reproduction. References Blevins, E., S. Jepsen, J. Brim Box, D. Nez, J. Howard, A. Maine, C. O'Brien. 2017. Extinction risk of western North American mussels: Anodonta nuttalliana, the Anodonta oreogonensis/kennerlyi clade, Gonidea angulata, and Margaritifera falcata. Freshwater Mollusk Biology and Conservation 20:71-88. Haag, W. R. 2012. North American freshwater mussels: natural history, ecology, and conservation. Cambridge University Press, New York, NY. Haag, W. R. and J. D. Williams. 2014. Biodiversity on the brink: an assessment of conservation strategies for North American freshwater mussels. Hydrobiologia 735: 45-60. Utah Wildlife Action Plan Joint Team (WAP). 2015. Utah Wildlife Action Plan: A plan for managing native wildlife species and their habitats to help prevent listing under the Endangered Species Act. Publication number 15-14. Utah Division of Wildlife Resources, Salt Lake City, Utah, USA. Williams, J. D., R. S. Butler, G. L. Warren, and N. A. Johnson. 2014. Freshwater Mussels of Florida. The University of Alabama Press, Tuscaloosa, AL.

Goal: improve understanding of freshwater mussel distribution, general population status, and threats across UDWR's Northern, Central, and Southern regions Objective: Conduct 1,310 visual-tactile surveys across 154 HUC10 basins in the Northern, Central, and Southern Regions by 2027. The breakdown of the project's total surveys and HUC10 basins per UDWR region are below: Northern Region (NR)- 57 HUC10 basins, 470 surveys Central Region (CR) - 51 HUC10 basins, 450 surveys Southern Region (SR) - 46 HUC10 basins, 390 surveys FY 23 tasks are provided for each UDWR region below: 1. NR: 120 surveys 2. CR: 80-100 surveys 3. SR: 130 surveys

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1) Utah Wildlife Action plan (UWAP 2015) -- Data gaps (inadequate understanding of distribution or rage) is one of the critical data gaps identified in this plan. Implementing this project will help clarify the status, distribution, and threats for Utah's native freshwater mussels, which allow UDWR to make more informed conservation decisions for these species. 2) UDWR Statewide Mollusk Conservation Strategy (Holcomb in prep.) -- This proposed project will benefit objective 2: Conduct surveys to expand knowledge of the distribution, habitat, abundance, and threats for SGCN mollusks (with freshwater mussels being a high priority). Holcomb, K. in prep. Utah Division of Wildlife Resources Statewide Mollusk Conservation Strategy. Utah Division of Wildlife Resources, Salt Lake City, Utah. Utah Wildlife Action Plan [UWAP]. 2015. Utah Wildlife Action Plan: a plan for managing native wildlife species and their habitats to help prevent listing under the Endangered Species Act. Publication number 15-14. Utah Division of Wildlife Resources, Salt Lake City, Utah, USA.

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Surveys and mollusk collections will be made by UDWR biologist, so mollusk collection permits are not be needed.

A total of 1310 surveys will be conducted across 154 HUC10 basins. UDWR biologists prioritized survey effort in HUC10 basins across the Northern, Central, and Southern regions based on historical freshwater mussel collections and effort, results of USU freshwater mussel eDNA surveys, UDWR fish stocking efforts (since fish can transport freshwater mussel glochidia to new waters), and the amount and suitability of aquatic habitat for freshwater mussels. High priority HUC10 basins will receive 10 surveys; low priority sites will receive 5 surveys. Survey locations within each HUC10 basin will be non-randomly selected to maximize the chance of detecting freshwater mussels. High priority survey areas include water bodies that have been stocked with fish by UDWR, water bodies with historical freshwater mussel collections, perennial water bodies, and higher order streams (3rd order and higher). Surveys efforts in FY23 will focus on high priority HUC10 basins, and in particular, priority HUC10 basins where there are anecdotal accounts of extant mussel populations that have not been thoroughly surveyed. Surveys will be conducted using visual-tactile methods (recommended in the UDWR Statewide Mollusk Strategy; Holcomb, in prep). Surveyors will use snorkeling gear and hand grubbing techniques to detect mussels in the substrate of lakes, reservoirs, streams, rivers, and wetlands. Surveys will be conducted for at least 1 person hour (30 minutes if there are two surveyors). Surveys can be conducted longer if surveyors suspect additional time would lead to positive detection of mussels, but surveys should not exceed 2 person hours in most cases. This time restraint is intended to ensure survey effort is adequately spread over a larger area to better understand the mussel species distributions. Since snorkeling gear will be used, survey depth will be restricted to 6 feet. Surveyors will focus on examining all major habitat types in an area (e.g., range of depths, pool/riffle/run, range of sediment types, vegetated areas). Surveys will be conducted during baseflow conditions to maximize detection of the mussels. Surveyors will not overlap in the areas they search, and the findings of each surveyor will be recorded separately (this will allow for occupancy modeling in the future, if desired). Mussels will be held in mesh bags during the survey so that data can be recorded for each surveyor's catch at the end of the survey. At the end of the survey, each surveyor will record on the mussel species present (Winged Floater, Western Pearlshell and non-native species), number of mussels of each species and number of live and dead individuals. Collectively, surveyors will then select 10 mussels to measure (including the smallest and largest individuals). These 10 mussels will also be checked for gravidity (are the gills puffy due to the presence of eggs or glochidia in the gills?). Collecting mussel measurements and gravidity data will help determine whether the population is successfully reproducing. Empty shell vouchers (3 of varying sizes) will be kept for each survey location. When larger (~50+ individuals), new populations are encountered, 3 live individuals (of varying sizes) will be preserved for future genetic and morphologic analyses (western Anodonta taxonomy is still in flux). Surveyors will also record date, survey time, surveyor names, location description, coordinates, survey area, water quality, habitat description, and threats for each survey site. Any non-native species that are encountered (Asian Clam, snails, crayfish, plants) and aquatic SGCN species will be recorded on the data sheet as well. Survey data will be reported to the UDWR mollusk coordinator and UDWR Heritage program at the end of each calendar year. Progress toward completing XXX surveys in XXX HUC10 basins will be evaluated annually using GIS tools. Final project outcomes will be a completion report, a freshwater mussel GIS layer that can be used for UDWR management and conservation decision making, and updated s-ranks for Winged Floater and Western Pearlshell.

Monitoring species status and effectiveness monitoring (of a project) are not objectives of this project. However, data generated from this project will be used to inform future mollusk monitoring efforts by UDWR.

This is currently a UDWR project, though there is room to bring on additional partners in future years. UDWR Native Aquatic Biologists are currently leading the survey effort, but Aquatic Invasive Species biologists and UDWR Sportfish Biologists will likely contribute to the overall survey effort in 2023.

This project is expected to be completed in 5 years or less. The more partners that can be involved in this project, the sooner the project will be completed. After the first year of surveys, the project will be evaluated to determine if the methods are appropriate for addressing the project objectives. For example, changes to the number of surveys per HUC10 basin, survey time, and survey method (visual-tactile vs. eDNA) be needed.

Freshwater mussels are part of healthy, functional aquatic ecosystems. Any steps that UDWR takes to restore freshwater mussel populations (e.g., stream habitat improvement, dam removal) will also benefit the other aquatic invertebrates and fishes. Taking steps to prevent freshwater mussels from being listed under the Endangered Species Act will be important to reduce economic impacts to Utahns. Since freshwater mussels are associated with a variety of aquatic habitats, federally listing them could affect acquisition of water rights, groundwater pumping rates, cattle ranching practices, fishing regulations, and housing development, though the extent of the economic impact would depend on which freshwater mussels species are listed.