Influence of Habitat on Eight Populations of Rio Grande Cutthroat Trout in Northern New Mexico
Dates
Start Date
2016-01-15
End Date
2019-12-30
Citation
Caldwell, C.A., B. Huntsman, and A.J. Lynch. 2020. Influences of Changes in Discharge and Stream Temperature on Eight Populations of Rio Grande Cutthroat Trout in Northern New Mexico. https://doi.org/10.21429/kbmw-6z60
Summary
The impacts of climate change on cold water species will likely manifest in populations at the trailing edge of their distribution. Rio Grande cutthroat trout (Oncorhynchus clarkii virginalis, RGCT) occupy arid southwestern U.S.A. streams at the southern-most edge of all cutthroat trout distributions; thus making RGCT particularly vulnerable to the anticipated warming and drying in this region. However, RGCT may possess a portfolio of life-history traits that aide in their persistence, attributes commonly observed in trailing edge populations. We used otolith and multistate capture-mark-recapture data collected along a temperature and stream drying gradient to determine how these environmental constraints influence life-history trait [...]
Summary
The impacts of climate change on cold water species will likely manifest in populations at the trailing edge of their distribution. Rio Grande cutthroat trout (Oncorhynchus clarkii virginalis, RGCT) occupy arid southwestern U.S.A. streams at the southern-most edge of all cutthroat trout distributions; thus making RGCT particularly vulnerable to the anticipated warming and drying in this region. However, RGCT may possess a portfolio of life-history traits that aide in their persistence, attributes commonly observed in trailing edge populations. We used otolith and multistate capture-mark-recapture data collected along a temperature and stream drying gradient to determine how these environmental constraints influence life-history trait expression (length- and age-at-maturity), demography, and extirpation risk in RGCT populations from northern New Mexico, U.S.A. We found the rate at which RGCT reached maturity was highest at warm to intermediate stream temperatures, which was the demographic trait most strongly linked to RGCT persistence. Interestingly, older life-stages contributed more to population growth as temperatures decreased, providing further evidence of strong temperature effects controlling life-history trait expression in RGCT. Precipitation, however, had little effect on RGCT population dynamics and was likely influenced by the uncharacteristically wet years (2016-2017) during this study. Regardless, our results suggest that RGCT persistence depends on temperature-influenced diversity in life-history trait expression (e.g., longevity, age-at-maturity). Plasticity in trait expression is an important life-history characteristic of coldwater species, and may be vital for trailing edge populations to persist in a changing climate.
The purpose of the data collected was to assess the impact that habitat (runs, riffles, pools, substrate, wetted width and depth, stream cover, and canopy) have on the life-history traits, persistence, and productivity of Rio Grande Cutthroat Trout (Oncorhynchus clarkii virginalis, RGCT) populations. This work will provide insight into the current and future threats of RGCT populations under environmental and biological pressures (e.g., drought, temperature). We empirically assessed the effects of habitat variables on life-history traits (i.e., age- and length-at-maturity) and vital rates (i.e., apparent survival, population growth, recruitment), and developed population models from these vital rate relationships with respect to habitat variables to better understand the risks to RGCT persistence.
