Geology topics

Ninh V. Vu

Publications and source records attributed to Ninh V. Vu.

4 recordsLinked to original sources

USGS2018

Effects of air exposure during simulated catch-and-release angling on survival and fitness of Yellowstone Cutthroat Trout

Concerns have been raised regarding the practice of exposing fish to air during catch-and-release (C&R) angling. The purpose of this study was to evaluate the effects of air exposure on short- and long-term survival and progeny production of Yellowstone Cutthroat Trout Oncorhynchus clarkii bouvieri . Prespawn adults were sampled at a weir during upstream migration in 2016 and 2017, exposed to a simulated angling event of 102 s, and then exposed to air for a randomly selected duration of 0, 30, or 60 s. An additional control group was added during 2017 in which fish were not exposed to simulated angling or air. In total, 1,519 fish were sampled in 2016, and 744 fish were sampled in 2017. Additionally, age-0 fish (2016: n = 2,924; 2017: n = 1,492) were collected to evaluate the effects of air exposure on the production of progeny. No effect of angling itself or of angling and air exposure was observed on short-term (≤60 d posttreatment) or long-term (>1 year posttreatment) survival of adults, with one exception. During 2016, fish that had been air exposed for 60 s had a statistically higher short-term survival rate than fish that received no air exposure. Air exposure had no effect on the proportion of fish that successfully spawned. Regression analysis revealed that neither angling nor air exposure affected progeny production. Considering that much of the literature, as well as this study, reports little to no influence of air exposure on salmonid mortality or reproductive success, it seems highly unlikely that air exposure of less than 60 s during C&R angling would have negative population-level effects.

Idaho↗

USGS2017

Production and evaluation of YY-male Brook Trout to eradicate nonnative wild brook trout populations

Nonnative Brook Trout Salvelinus fontinalis were introduced throughout western North America in the early 1900s, resulting in widespread self-sustaining populations that are difficult to eradicate and often threaten native salmonid populations. A novel approach for their eradication involves use of YY male (MYY) Brook Trout (created in the hatchery by feminizing XY males and crossing them with normal XY males). If MYY Brook Trout survive after stocking, and reproduce successfully with wild females, in theory this could eventually drive the sex ratio of the wild population to 100% males, at which point the population would not be able to reproduce and would be eradicated. This study represents the first successful development of a FYY and MYY salmonid broodstock, which was produced in four years at relatively low cost. Field trials demonstrated that stocked hatchery MYY Brook Trout survived and produced viable MYY offspring in streams, although reproductive fitness appeared to have been lower than their wild conspecifics. Even if reduced fitness is the norm in both streams and alpine lakes, our population simulations suggest that eradication can be achieved in reasonable time periods under some MYY stocking scenarios, especially when wild Brook Trout are simultaneously suppressed in the population.

Conference Paper↗

USGS2013

Microsatellites indicate minimal barriers to mule deer Odocoileus hemionus dispersal across Montana, USA

To better understand the future spread of chronic wasting disease, we conducted a genetic assessment of mule deer Odocoileus hemionus population structure across the state of Montana, USA. Individual based analyses were used to test for population structure in the absence of a priori designations of population membership across the sampling area. Samples from the states of Wyoming, Colorado and Utah were also included in the analysis to provide a geographic context to the levels of population structure observed within Montana. Results showed that mule deer across our entire study region were characterized by weak isolation by distance and a lack of spatial autocorrelation at distances > 10 km. We found evidence for contemporary male bias in dispersal, with female mule deer exhibiting higher mean individual pairwise genetic distance than males. We tested for potential homogenizing effects of past translocations within Montana, but were unable to detect a genetic signature of these events. Our results indicate high levels of connectivity among mule deer populations in Montana and suggest few, if any, detectable barriers to mule deer gene flow or chronic wasting disease transmission.

Wildlife Biology↗

USGS2011

Genetic variation in westslope cutthroat trout Oncorhynchusclarkii lewisi : implications for conservation

Twenty-five populations of westslope cutthroat trout from throughout their native range were genotyped at 20 microsatellite loci to describe the genetic structure of westslope cutthroat trout. The most genetic diversity (heterozygosity, allelic richness, and private alleles) existed in populations from the Snake River drainage, while populations from the Missouri River drainage had the least. Neighbor-joining trees grouped populations according to major river drainages. A great amount of genetic differentiation was present among and within all drainages. Based on Nei’s DS, populations in the Snake River were the most differentiated, while populations in the Missouri River were the least. This pattern of differentiation is consistent with a history of sequential founding events through which westslope cutthroat trout may have experienced a genetic bottleneck as they colonized each river basin from the Snake to the Clark Fork to the Missouri river. These data should serve as a starting point for a discussion on management units and possible distinct population segments. Given the current threats to the persistence of westslope cutthroat trout, and the substantial genetic differentiation between populations, these topics warrant attention.

Idaho, Montana↗