Connectivity of fish populations is a crucial question for fisheries conservation and the development of spatial management plans. Both adult and larval movement define the extent and direction of ecological and evolutionary overlap between geographic regions and, therefore, how we define stocks for management purposes. Within that context, my work...
Estuaries, which provide viable habitat for a plethora of fish and invertebrate species, are being increasingly impacted by anthropogenic and natural forces. Estuaries are important nursery habitat for young-of-the-year (YOY) Pacific rockfish (Sebastes spp.). Yaquina Bay, a marine-dominated estuary on the central Oregon Coast, served as a study site for...
Black Rockfish are important commercial and recreational species and understanding their biology is useful in developing best management practices. A common means to assess diet in both freshwater and marine fishes is stomach content analysis, which can determine diet composition and infer foraging behaviors. We conducted a stomach content analysis...
The effects of Marine protected areas (MPAs) on adult fish populations depend on the degree of protection provided, which is partly a function of MPA size and the spatial extent of fish movements. The Redfish Rocks Marine Reserve (RRMR) and MPA, located on the south coast of Oregon near Port...
Recent emphasis on linkages between essential fish habitat and fish stock productivity has raised concerns about the management of fishing activities such as trawling, which have the potential to impact fish habitat. Knowing specifically where and how intensively trawl effort has occurred over time provides ecologists with the necessary background...
The California Current Large Marine Ecosystem (CCLME), located on the eastern boundary of the North Pacific Ocean, is highly dynamic, with variable conditions driven by seasonal upwelling, regional oceanography, and broad scale climate patterns. In the last decade, the northeast Pacific Ocean has experienced several marine heatwaves (MHWs), prolonged periods...
The role that anthropogenic and natural habitats in estuaries play in long-term population trends for Oregon’s nearshore marine fishes is poorly understood, in part due to limited temporal sampling. One important nearshore marine group is northeastern Pacific rockfishes (Sebastes spp.), which are highly diverse, with around 96 documented species, and...
The quality and availability of forage fishes and invertebrates can affect the behavior and productivity of predators that rely on these resources. This study measures the proximate composition of forage fishes and invertebrates from the southeastern Bering Sea to estimate prey energy density (quality) using a method that is ecologically...
In the past, sharks, skates and ray species have mainly occurred in incidental fisheries. Now they are increasingly being directly targeted due to the depleted status of traditionally targeted species. The life history characteristics of many elasmobranch species make them more sensitive to high rates of fishing mortality. The combination...
Pacific lamprey is an important cultural and ecological species to freshwater ecosystems of the Pacific Northwest. Lamprey often rear in low gradient portions of watersheds that have high exposure to climate warming, yet very little is known about their thermal physiology in comparison with other anadromous fishes such as Pacific...
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Scott A. Heppell
Pacific lamprey is an important cultural and ecological species to freshwater
Recent studies suggest that competition from brook trout (Salvelinus fontinalis; EBT) may have negative effects (e.g. displacement) on Lahontan cutthroat trout (Oncorhynchus clarki henshawi; LCT). Results from these studies have failed to elucidate the responsible mechanisms and have not examined if changing environmental conditions result in competitive/subordinate role reversals. The...
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...
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Scott A. Heppell
Over the last decade, the Oregon Department of Fish and Wildlife (ODFW
Passive acoustic monitoring is a valuable tool for observing the status of marine environments. Comparisons of underwater soundscapes over temporal and spatial scales can provide data to inform marine conservation efforts, including protection of threatened and endangered species. This dissertation utilizes passive acoustic data collected via a broadly spaced array...
Lingcod (Ophiodon elongatus) are known to utilize certain estuaries along the Pacific coast of the United States, but the importance of these habitats to the coast-wide population is not well understood. In this study, general patterns of estuarine habitat use were assessed by tracking the movement of sub-adult and adult...
Thiamine (vitamin B₁) is required by all living organisms for carbohydrate metabolism and synthesis of amino acids. Thiamine deficiency is responsible for several related classes of early life stage mortality disorders in salmonines, including Thiamine Deficiency Complex (TDC) in the Laurentian Great Lakes, Cayuga Syndrome in the Finger Lakes, and...
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Scott A. Heppell
Thiamine (vitamin B1) is required by all living organisms for carbohydrate
The goal of this research was to characterize thermal habitat requirements for juvenile redband steelhead trout (Oncorhynchus mykiss gairdneri) in the South Fork John Day River (SFJD), Oregon using physiological indicators of fish condition. Physiological indices of fish condition measured were whole body lipid content and heat shock proteins, specifically...
The goal of this research was to characterize thermal habitat requirements for juvenile redband steelhead trout (Oncorhynchus mykiss gairdneri) in the South Fork John Day River (SFJD), Oregon using physiological indicators of fish condition. Physiological indices of fish condition measured were whole body lipid content and heat shock proteins, specifically...
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....
The red sea urchin, Strongylocentrotus franciscanus, is one of the three species of strongylocentroids found on the west coast of North America between Baja California and Kodiak, Alaska. It belongs to the phylum Echinodermata, and it is one of the largest species of sea urchins. Since 1970, red sea urchins...
Marine Team is a student effort to examine spatial and temporal variation of fish species within Yaquina Bay. Marine Team was developed at OSU as a seminar course with a field sampling component, to help students of marine ecology get “hands on” experience with data collection and analysis. We set...