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Conclusions: In fragmented watersheds, macrohabitat attributes measured at the patch scale were far more effective in predicting trout translocation success than measurements taken at the landscape scale Thresholds/Learnings: As a course filter indicator of cutthroat trout translocation success, the study found that translocations have a greater than 50% chance of fruitful establishment in watersheds >14.7km2 in area. Synopsis: This study aimed to identify stream-scale and basin-scale macrohabitat attributes limiting successful translocation and persistence of native cutthroat trout populations in fragmented landscapes along the Rio Grande. The study developed models of habitat attributes measured at two scales...
Invasion by nonnative brook trout (Salvelinus fontinalis) often results in replacement of cutthroat trout (Oncorhynchus clarki) in the inland western United States, but the underlying mechanisms are not well understood. We conducted a four-year removal experiment to test for population-level mechanisms (i.e., changes in recruitment, survival, emigration, and immigration) promoting invasion success of brook trout and causing decline of native Colorado River cutthroat trout (O. c. pleuriticus). We chose 700–1200 m segments of four small mountain streams where brook trout had recently invaded cutthroat trout populations, two each at mid elevation (2500–2700 m) and high elevation (3150–3250 m), and annually removed...
The Rio Grande cutthroat trout, Oncorhynchus clarkii virginalis, has declined precipitously over the past century, and currently exhibits a highly fragmented distribution within the Canadian, Pecos and Rio Grande river systems of the western United States. The relationships between populations in the three river drainages, and between O. c. virginalis and the closely related taxa O. c. pleuriticus and O. c. stomias, are not well understood. In order to guide management decisions for the subspecies, we investigated the distribution of variation at 12 microsatellite loci and two regions of the mitochondrial genome. We observed a high level of genetic differentiation between O. c. virginalis populations occupying different...
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Streams across the world are highly fragmented due to the presence of in-stream barriers (e.g., dams and stream-road crossings), many of which restrict or block fish passage. Retrofitting or replacing these structures is a high priority for restoring habitat connectivity for native fishes and other aquatic organisms in the Pacific Northwest. The task of restoring habitat connectivity for problematic stream-road crossings is daunting given the many thousands of barriers that are present and the massive financial investments required. Further, the potential risks to road infrastructure from flooding, debris flows, and climate change will need to be addressed to ensure the best allocation of resources. In this study,...
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Conclusions: At small spatial scales, where extirpation risks are high, landscape fragmentation will likely have long-term negative consequences on the genetic variation of individual assemblages of coastal cutthroat trout. Thresholds/Learnings: Synopsis: This study aimed to determine if coastal cutthroat trout were genetically structured within streams and to assess the effects of habitat fragmentation on coastal cutthroat trout genetic variation. Habitat fragmented by roads and other human disturbances acted as dispersal barriers, which strongly influenced coastal cutthroat trout genetic structure, diversity, and differentiation. At range-wide spatial scales, fragmentation potentially contributes to coastal cutthroat...
A paradox of invasion biology is that even though native species are locally adapted to environmental conditions, nonnative species without this advantage often invade. Ecologists have advanced four main theories to explain why invaders are successful in some places and not others: biotic resistance, environmental resistance, human disturbance, and natural enemies. However, none of these theories alone can account for invasions by two trout species outside their native ranges in North America. Brook trout (Salvelinus fontinalis) are able to displace native cutthroat trout (Oncorhynchus clarkii) in the inland western US, but are themselves displaced by nonnative rainbow trout (O. mykiss) in the southeastern US. An...
Salmonids, a group of coldwater-adapted fishes of enormous ecological and socio-economic value, historically inhabited a variety of freshwater habitats throughout the Pacific Northwest (PNW). Over the past century, however, populations have dramatically declined due to habitat loss, overharvest, and invasive species. Consequently, many populations are listed as threatened or endangered under the U.S. Endangered Species Act. Complicating these stressors is global warming and associated climate change. Overall, aquatic ecosystems across the PNW are predicted to experience increasingly earlier snowmelt in the spring, reduced late spring and summer flows, increased winter flooding, warmer and drier summers, increased...
    map background search result map search result map Minimum habitat requirements for establishing translocated cutthroat trout populations. Influences of barriers to movement on within-watershed genetic variation of coastal cutthroat trout Where the Stream Meets the Road: Prioritizing Culvert Replacement for Fish Passage - Thesis Influences of barriers to movement on within-watershed genetic variation of coastal cutthroat trout Where the Stream Meets the Road: Prioritizing Culvert Replacement for Fish Passage - Thesis Minimum habitat requirements for establishing translocated cutthroat trout populations.