Influence of Desert Springs on Habitat of Endangered Zuni Bluehead Sucker (Catostomus discobolus yarrowi)

ABSTRACT Located on the southeastern part of the Colorado Plateau, the Zuni Mountains are home to the endangered Zuni Bluehead Sucker (ZBS) (Catostomus discobolus yarrowi). A 4-year study was conducted on a low-flow (<80 cm3/s) hillslope spring and intermittent stream, that are home to one of the three remaining ZBS populations. Seasonal measurements of physical and hydrochemical parameters were used to estimate the contribution of groundwater to the stream and to identify geologic and hydrologic controls for the spring discharge. Seasonal concentrations and standard deviations (s) of Mg2+ were used to determine that the spring water (5.6 mg/L; s = 0.4) and surface water up-gradient from the spring input (10.7 mg/L; s = 11.2) is from different sources. Surface water down-gradient from the spring input maintain ZBS populations and is a mixture of spring water and up-gradient surface water. Mass solution mixing was used to determine spring water contributes up to 99 percent of the down-gradient water during drier seasons. Isotopes (δD, δ18O, 3H) indicate that the spring water has been recharged primarily from snowmelt within the last 70 years, while up-gradient surface water is seasonal runoff from rain and snowmelt. Continuous monitoring of dissolved oxygen (DO) mean concentrations (up-gradient = 1.6 mg/L and down-gradient = 5.7 mg/L) indicated that surface water up-gradient from the spring input are anoxic and unable to support ZBS. Surface water down-gradient from the spring input maintain appropriate DO concentrations due to perennially discharging spring waters re-aerating downstream habitats.

Gene flow and species delimitation in fishes of Western North America: Flannelmouth (Catostomus latipinnis) and Bluehead sucker (C. Pantosteus discobolus)

The delimitation of species-boundaries, particularly those obscured by reticulation, is a critical step in contemporary biodiversity assessment. It is especially relevant for conservation and management of indigenous fishes in western North America, represented herein by two species with dissimilar life-histories co-distributed in the highly modified Colorado River (i.e., Flannelmouth Sucker, Catostomus latipinnis; Bluehead Sucker, C. Pantosteus discobolus). To quantify phylogenomic patterns and examine proposed taxonomic revisions, we first employed double-digest restriction-site associated DNA sequencing (ddRAD), yielding 39,755 unlinked SNPs across 139 samples. These were subsequently evaluated with multiple analytical approaches and by contrasting life history data. Three phylogenetic methods and a Bayesian assignment test highlighted similar phylogenomic patterns in each, but with considerable difference in presumed times of divergence. Three lineages were detected in Bluehead Sucker, supporting elevation of C. P. virescens to species-status, and recognizing C. P. discobolus yarrowi (Zuni Bluehead Sucker) as a discrete entity. Admixture in the latter necessitated a reevaluation of its contemporary and historic distributions, underscoring how biodiversity identification can be confounded by complex evolutionary histories. In addition, we defined three separate Flannelmouth Sucker lineages as ESUs (Evolutionarily Significant Units), given limited phenotypic and genetic differentiation, contemporary isolation, and lack of concordance (per the genealogical concordance component of the phylogenetic species concept). Introgression was diagnosed in both species, with the Little Colorado and Virgin rivers in particular. Our diagnostic methods, and the alignment of our SNPs with previous morphological, enzymatic, and mitochondrial work, allowed us to partition complex evolutionary histories into requisite components, such as isolation versus secondary contact.

Multispecies and Watershed Approaches to Freshwater Fish Conservation

<em>Abstract</em>—The Weber River is primarily known as a blue-ribbon Brown Trout <em>Salmo trutta </em>fishery; however, this river also supports populations of two jeopardized fishes, Bonneville Cutthroat Trout <em>Oncorhynchus clarkii utah </em>and Bluehead Sucker <em>Catostomus discobolus</em>. At least one population of Bonneville Cutthroat Trout in the Weber River provides an important and popular local fishery and expresses a fluvial life history where main-stem individuals grow large (300–500 mm total length) and migrate into small tributaries for spawning. Bluehead Suckers currently occur in the main stem of the Weber River, where they travel distances of 20 km between spawning and overwintering habitats. The habitat for both species has been fragmented by more than 300 barriers composed of irrigation diversions, road crossings, and utility stream crossings. Beginning in 2010, the Utah Division of Wildlife Resources and Trout Unlimited began undertaking barrier removal for native fish as a priority conservation action. Initially, the effort to reconnect habitat was slow and the lack of relationships with stakeholders such as water users, government agencies, private landowners, and utility companies was hampering progress with habitat reconnection. New barriers were being built at a faster rate than barriers were being removed. To build these relationships, a steering committee was formed to secure a small grant, hire a consulting firm, organize stakeholder meetings to identify broad stakeholder priorities, and write a watershed plan that ultimately identified Bonneville Cutthroat Trout and Bluehead Sucker as priority conservation targets. The watershed plan and subsequent stakeholder meetings developed a framework for the Weber River Partnership. The partnership holds an annual symposium where larger watershed issues are discussed. The symposium also provides a platform where all stakeholders can understand the activities occurring throughout the watershed and where there are opportunities to collaborate. The Weber River Partnership has provided a forum where fisheries managers have told the story of Bonneville Cutthroat Trout and Bluehead Sucker and the importance of habitat connectivity. Through collaborative relationships with nontraditional partners, the relevance of fisheries in the Weber River has been realized. Further relevance in the watershed is evidenced by the development of a wide range of on-the-ground actions. Fish passage has been re-established at three main-stem and four tributary barriers. Additional projects are in various stages of development, including a large fish ladder that will be built as part of a Federal Energy Regulatory Commission relicensing project at a small hydroelectric dam, and we continue to be contacted by water users with interest in developing irrigation diversion reconstruction projects that incorporate fish passage.