After hatchery-reared salmonids are released into the wild, their survival and performance are
frequently lower than those of wild conspecifics. Additionally, negative effects of hatchery fish on wild fish are cited as factors affecting the recovery of salmonid populations. Alternative hatchery rearing environments and release practices have been proposed to...
One aspect of diadromy that has received little attention is buoyancy regulation in fish moving between freshwater and marine environments. Because of density differences between the two water types, fish must alter their whole-fish density (WFD) or they will become positively (float) or negatively (sink) buoyant as they change environments....
Low-tech habitat restoration techniques, including Stage 0 treatments, are increasingly applied but often lack robust evaluation of their effects. In 2018, one kilometer of the South Fork McKenzie (SFMK) River, OR was modified to the Stage 0 condition for the benefit of ESA-listed Chinook by raising the incised channel to...
Of all Pacific salmonids, Chinook salmon Oncorhynchus tshawytscha display the greatest variability in return times to freshwater. The molecular mechanisms of these differential return times have not been well described. Current methods, such as long serial analysis of gene expression (LongSAGE) and microarrays, allow gene expression to be analyzed for...
Linked atmospheric and wildfire changes will complicate future management of native coldwater fishes in fire-prone
landscapes, and new approaches to management that incorporate uncertainty are needed to address this challenge. We used a
Bayesian network (BN) approach to evaluate population vulnerability of bull trout (Salvelinus confluentus) in the Wenatchee River...
The 20-year US GLOBEC (Global Ocean Ecosystem Dynamics)
program examined zooplankton populations and their predators in four coastal
marine ecosystems. Program scientists learned that environmental controls on
zooplankton vital rates, especially the timing and magnitude of reproduction, growth,
life-cycle progression, and mortality, determine species population dynamics,
seasonal and spatial distributions,...
This study examined the potentially stressful
effects of tagging juvenile rainbow trout Oncorhynchus mykiss
with passive integrated transponder (PIT) tags by measuring
short-term (<120-h) changes in plasma concentrations of
cortisol and hepatic heat shock protein 70 (hsp70). In a
laboratory experiment, plasma cortisol levels were measured
in fish before they...
Two ecologically important lamprey species found in the endorheic Goose Lake Basin face conservation threats; however, relatively little is known about their habitat needs or spatial distribution. Lamprey and their habitat are often found to be patchy; to evaluate these relationships for the lamprey in this basin, I utilized a...
Acoustic position estimation is used where high accuracy navigation is required over a small area, such as for searching or for collecting gravitational or geomagnetic data. In this position estimation method, a surface ship or submersible periodically sends out a high-frequency acoustic 'ping' at a prearranged frequency. This ping is...