Affiliation:
1. Department of Fish, Wildlife and Conservation Ecology New Mexico State University Las Cruces New Mexico USA
2. U.S. Geological Survey New Mexico Coopertive Fish and Wildlife Research Unit Las Cruces New Mexico USA
3. U.S. Geological Survey National Climate Adaptation Science Center Reston Virginia USA
Abstract
AbstractEnvironmental stressors associated with a changing climate and non‐native fish, individually, represent significant threats to native fish conservation. These threats can exacerbate risks to native fishes when conditions interact at the trailing edge of a population's distribution. We collected capture–mark–recapture data for Rio Grande cutthroat trout (RGCT, Oncorhynchus clarkii virginalis) at the trailing edge of all cutthroat trout distributions from eight northern New Mexico populations. We used a factorial sampling design from streams characterised as “cool” or “warm” and whether RGCT were sympatric with non‐native brown trout (Salmo trutta). We tested competing hypotheses that warm temperatures, reduced flows, high densities and sympatry with brown trout would negatively impact RGCT apparent survival rates. We found the strongest evidence for a non‐native trout interaction with total trout density affecting RGCT apparent survival rates. Our results are consistent with patterns observed in northern cutthroat trout populations where non‐native salmonids negatively impacted apparent survival rates. We also found that a negative density effect was observed on allopatric RGCT and sympatric brown trout apparent survival, but a positive density effect was observed for sympatric RGCT. These results suggest higher density populations of RGCT may be more resilient to displacement by non‐native trout than low‐density populations.
Subject
Ecology,Aquatic Science,Ecology, Evolution, Behavior and Systematics