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.

Adfluvial salmonids have engineering but not fertilization impacts in tributaries of a central Utah reservoir

Migratory fishes can affect tributary ecosystem properties given their potential to introduce nutrients (fertilize) and physically modify habitat (engineer) during spawning. Nonetheless, migrant effects are frequently context-dependent, and it is useful to understand their strength relative to other potential ecosystem drivers. We examined whether tributary ecosystem properties varied in response to migrations of two adfluvial salmonids, taking advantage of differences in migration timing and reproductive strategy between species, as well as hydrogeomorphic differences between a pair of tributaries. For analyses, we used a model comparison approach to evaluate migrant effects relative to other possible drivers. We observed that Bonneville cutthroat trout (Oncorhynchus clarkii utah) engineered benthic chlorophyll a in redds, with reduction (51% ± 16% decrease) generally occurring during migrations. Contrary to expectations, migrant fertilization effects were not pronounced even in the more retentive tributary during migration by species (kokanee, Oncorhynchus nerka) that exhibited high postspawning mortality. Based on multimodel comparisons, isolated migrant effects were not the primary influence on measured ecosystem properties. Our findings underscore the need to consider different biotic and abiotic conditions that can mediate migratory fish effects.