Depleted species of rockfish (Sebastes spp.) from the Northeast Pacific experience high discard mortality due to "barotrauma," induced from the rapid change in pressure during capture. Research suggests rockfish have the potential to survive barotrauma if immediately recompressed, but the potential for long-term recovery is unknown. In this project, we...
The number of endangered species is rapidly increasing while paucity of adequate information and resources delays establishment of conservation actions. The IUCN’s listing system is insufficient to determine conservation priorities and many species lack information even to be evaluated (i.e., “data deficient”). Here I proposed and tested the Rapid Endangered...
Research conducted on humpback whitefish Coregonus pidschian in the Copper River Delta, Alaska has revealed a complex life history involving seasonal migrations and the occupation of a variety of freshwater and marine habitats including lacustrine, riverine, estuarine, and marine. Forty-five whitefish were tagged with radio transmitters in 2006 and 2007,...
Despite evidence that juvenile Chinook salmon (Oncorhynchus tshawytscha) utilize North Pacific estuaries for growth and salinity acclimation, research in the Columbia River estuary has lead to opposing hypotheses about the estuary’s importance as a salmon rearing environment. Many contemporary tagging studies indicate that salmon residency within the estuary is short...
Dietary iodine may play an important role in the nutritional health of freshwater fish larvae. Artemia, commonly used for the culture of larval zebrafish (Danio rerio), contain low concentrations of iodine when compared with wild zooplankton. Water-soluble micronutrients, such as iodine, are difficult to deliver to Artemia due to rapid...
This dissertation focuses on the predator-prey relationship between two species of avian predators, Caspian terns (Hydroprogne caspia) and double-crested cormorants (Phalacrocorax auritus), and one of their important prey types, juvenile salmonids (Oncorhynchus spp.), in the Columbia River estuary of Oregon and Washington states during the period 1998 – 2007. I...
Coastal cutthroat trout (Oncorhynchus clarkii clarkii) and cottids (Cottus spp) commonly co-occur in headwater streams in western Oregon. Little is known about the comparative trophic ecology of these species or how they respond to seasonal scarcity of resources. In this study I evaluated the seasonal variability in diets and consumption...
Over the last decade, the Oregon Department of Fish and Wildlife (ODFW) has documented a precipitous decline in the Crooked River redband trout (Oncorhynchus mykiss) population, prompting this study to address potential factors contributing to the decline. There are two main goals to this project: (1) identify potential factors contributing...
The 100 North Pacific rockfish species in the genus Sebastes are highly diverse. Rockfishes fertilize their eggs internally and release swimming larvae. Complex courting behaviors may allow female rockfish to be selective about their mates and may promote and maintain speciation. In this study, I applied genetic techniques to survey...
In the Pacific Northwest, several species of rockfishes (Sebastes spp.) are under extreme conservation measures due to low population levels. Although currently at healthy population levels, one species of interest is the black rockfish (S. melanops), which has been shown to utilize estuarine habitat during its early life history stages....