Christopher Guy, PhD (Former Employee)

The Pallid Sturgeon (Scaphirhynchus albus) Conservation Propagation and Stocking Program began stocking in the Missouri River above Fort Peck Reservoir in 1998 with 1997-year-class pallid sturgeon. Within the 1997-year class, all hatchery-origin pallid sturgeon females that reached reproductive maturation by 2016 underwent mass ovarian follicular atresia. Using combined historical and...

The native Yellowstone Cutthroat Trout (Oncorhynchus clarkii bouvieri Jordan and Gilbert, 1883) population in Yellowstone Lake, Yellowstone National Park, Wyoming, USA, is in decline because of competition from the introduced, invasive Lake Trout (Salvelinus namaycush Walbaum in Artedi, 1792). Gillnetting is used to suppress adult Lake Trout; however, methods are being developed to...

Hatchery-origin white sturgeon Acipenser transmontanus in the lower Columbia River, Canada are approaching puberty, and describing the reproductive structure of the population is critical to determine if they are capable of contributing to spawning events in the wild, a key management uncertainty. Few studies have compared the accuracy of available tools (histology, ultrasound, endoscopy...

(1) Many forage fishes, such as Leucisids (minnows) have depauperate studies on diet composition or stable isotope signatures, as these fishes are often only viewed as food for higher trophic levels. The need exists to understand and document the diet and stable isotope signatures of Leucisids (redside shiner, longnose dace, lake chub) in relation to the community ecology and food-web...

Invasive Lake Trout Salvelinus namaycush have altered the once-pristine Yellowstone Lake ecosystem through top-down effects by consuming Yellowstone Cutthroat Trout Oncorhynchus clarkii bouvieri. To conserve Yellowstone Cutthroat Trout and restore the ecosystem, a Lake Trout gillnetting program was implemented to suppress the invasive population. We evaluated the spatial structure of...

Little is known about the life-history traits exhibited by burbot (Lota lota) throughout their circumpolar range. Monitoring PIT-tagged burbot between lentic and lotic habits and collection of demographic data (length, age, sex, and maturity) were used to answer the following questions in the Torrey Creek drainage of west-central Wyoming, USA: 1) is there plasticity in the life-history...

We measured gonad size (diameter and circumference) by ultrasound and used it as a metric to assign stage of maturity in Burbot Lota lota from Lake Roosevelt, Washington. We collected paired gonad tissue and ultrasound measurements monthly from November 2017 to March 2018 and processed gonad tissue for histological analysis to confirm stage of maturity. We measured gonad diameter and...

Lake charr Salvelinus namaycush life history and population dynamics metrics were reviewed to evaluate populations inside (n = 462) and outside (n = 24) the native range. Our goals were to create a database of metrics useful for evaluating population status and to test for large-scale patterns between metrics and latitude and lake size. An average lake charr grew from a 69-mm length at...

Despite unprecedented scientific productivity, Earth is undergoing a sixth mass extinction. The disconnect between scientific output and species conservation may be related to scientists studying the wrong species. Given fishes have a high extinction rate, we assessed the paradox between scientific productivity and science needed for conservation by comparing scientific output created...

Invasive species require management to mitigate their harmful effects on native biodiversity and ecosystem processes. However, such management can also have negative, unintended consequences on non-target taxa, ecosystem processes, and food web dynamics. In Yellowstone Lake, invasive lake trout (Salvelinus namaycush) have caused a decline in the native Yellowstone cutthroat trout...

Identifying and understanding functional process domains (sensu Montgomery, 1999) in rivers is paramount for linking the physical habitat template to ecosystem structure and function. To date, efforts to do this have been rare, especially in large rivers, as they require appropriate tools for quantifying habitat heterogeneity with fine-scale resolution across broad spatial extents. In...

Yellowstone Lake in Yellowstone National Park, USA, has the longest ongoing suppression program for non-native lake trout (Salvelinus namaycush) in the western USA. Harvest data from the suppression program, along with data from an assessment program initiated in 2011, was used to estimate lake trout abundance and mortality rates. Abundance and biomass estimates were used to estimate...