Status report on the Long-Term Experimental and Management Plan (LTEMP) Metrics for the Glen Canyon Dam adaptive management program
No abstract available.
Arizona, Nevada↗
Geology topics
Emily C. Omana Smith
Publications and source records attributed to Emily C. Omana Smith.
Quantifying the contributions of tributaries to large-river fish populations through mark-recapture modeling
Tributaries may play a vital role in maintaining populations of large river fishes, although the specific contributions of tributaries toward recruitment of river-wide populations are not often understood. Tributaries may experience fewer cumulative anthropogenic impacts relative to mainstem rivers and may offer more natural conditions supportive of native fish populations, which may provide opportunities for fish population restoration. Thus, an improved understanding of tributary-mainstem population dynamics may inform targeted conservation actions for spatially structured populations of large-river fishes. Colorado River tributaries in the Grand Canyon, Arizona, USA are a focus of imperiled Humpback Chub Gila cypha conservation, which includes translocations to enhance population redundancy and to expand the overall population. However, the fate of fish dispersed to the mainstem has not been thoroughly quantified. Using open population mark-recapture models, we quantified the relative contribution of three groups of Humpback Chub, including fish of confirmed tributary origin that were either translocated or produced in situ , and others presumed to be Colorado River mainstem origin fish, to three mainstem populations. Our specific study objectives were to 1) estimate Colorado River abundances of tributary and mainstem-origin fish over time, 2) compare relative group-specific contributions to three mainstem populations, and 3) compare group-specific survival rates of Humpback Chub in the Colorado River and in a tributary where a recent translocation has occurred. Tributaries contributed 26% and 43% of the overall abundance in two tributary inflow reach populations, and zero in a third, which we attributed to uncharacteristically low tributary survival immediately following translocation. In the mainstem, survival of tributary-origin fish was higher compared to mainstem-origin fish, suggesting an advantage of tributary residence. Our contrasting results from three different tributary inflow populations highlight the potential role for tributaries in sustaining large-river fish populations, which may have important implications for long-term maintenance of river metapopulations.
North American Journal of Fisheries Management↗
Life and death in a dynamic environment: Invasive trout, floods, and intraspecific drivers of translocated populations
Understanding the relative strengths of intrinsic and extrinsic factors regulating populations is a long-standing focus of ecology and critical to advancing conservation programs for imperiled species. Conservation could benefit from an increased understanding of factors influencing vital rates (somatic growth, recruitment, survival) in small, translocated populations, which is lacking owing to difficulties in long-term monitoring of rare species. Translocations, here defined as the transfer of wild-captured individuals from source populations to new habitats, are widely used for species conservation, but outcomes are often minimally monitored, and translocations that are monitored often fail. To improve our understanding of how translocated populations respond to environmental variation, we developed and tested hypotheses related to intrinsic (density dependent) and extrinsic (introduced rainbow trout Oncorhynchus mykiss , stream flow and temperature regime) causes of vital rate variation in endangered humpback chub ( Gila cypha ) populations translocated to Colorado River tributaries in the Grand Canyon (GC), USA. Using biannual recapture data from translocated populations over 10 years, we tested hypotheses related to seasonal somatic growth, and recruitment and population growth rates with linear mixed-effects models and temporal symmetry mark–recapture models. We combined data from recaptures and resights of dispersed fish (both physical captures and continuously recorded antenna detections) from throughout GC to test survival hypotheses, while accounting for site fidelity, using joint live-recapture/live-resight models. While recruitment only occurred in one site, which also drove population growth (relative to survival), evidence supported hypotheses related to density dependence in growth, survival, and recruitment, and somatic growth and recruitment were further limited by introduced trout. Mixed-effects models explained between 67% and 86% of the variation in somatic growth, which showed increased growth rates with greater flood-pulse frequency during monsoon season. Monthly survival was 0.56–0.99 and 0.80–0.99 in the two populations, with lower survival during periods of higher intraspecific abundance and low flood frequency. Our results suggest translocations can contribute toward the recovery of large-river fishes, but continued suppression of invasive fishes to enhance recruitment may be required to ensure population resilience. Furthermore, we demonstrate the importance of flooding to population demographics in food-depauperate, dynamic, invaded systems.
Arizona↗