Index Catalog // ScholarsArchive@OSU

Evidence for selective mortality in marine environments: the role of fish migration size, timing, and production type

Creator:: Claiborne, Andrew M., Miller, Jessica A., Weitkamp, Laurie A., Teel, David J., and Emmett, Robert L.
Abstract:: The underlying causes of mortality during critical life stages of fish are not well understood, nor is it clear if these causes are similar for naturally versus artificially propagated (i.e. hatchery) individuals. To assess the importance of selective mortality related to production type (hatchery vs. naturally produced) and size at...
Resource Type:: Article

Biotic and abiotic factors influencing forage fish and pelagic nekton community in the Columbia River plume (USA) throughout the upwelling season 1999–2009

Creator:: Litz, Marisa N. C., Emmett, Robert L., Bentley, Paul J., Claiborne, Andrew M., and Barceló, Caren
Abstract:: Large river plumes modify coastal environments and can impact production across multiple trophic levels. From 1999 to 2009, the assemblages of forage fish, predator fish, and other pelagic nekton were monitored in coastal waters associated with the Columbia River plume. Surveys were conducted at night to target vertically migrating species,...
Resource Type:: Article

Interannual variability in the Northern California Current food web structure: Changes in energy flow pathways and the role of forage fish, euphausiids, and jellyfish

Creator:: Ruzicka, James J., Brodeur, Richard D., Emmett, Robert L., Steele, John H., Zamon, Jeannette E., Morgan, Cheryl A., Thomas, Andrew C., and Wainwright, Thomas C.
Abstract:: The Northern California Current (NCC) is a seasonally productive and open ecosystem. It is home to both a diverse endemic community and to seasonally transient species. Productivity and food web structure vary seasonally, interannually, and decadally due to variability in coastal upwelling, climate-scale physical processes, and the migratory species entering...
Resource Type:: Article

Large medusae in surface waters of the Northern California Current: variability in relation to environmental conditions

Creator:: Suchman, Cynthia L., Brodeur, Richard D., Daly, Elizabeth A., and Emmett, Robert L.
Abstract:: Blooms of jellyfish around the world have been correlated with climatic variables related to environmental causes. Sizeable populations of large medusae, primarily Chrysaora fuscescens and Aequorea sp., appear annually in shelf waters of the Northeast Pacific Ocean. Previous research has shown that C. fuscescens is abundant seasonally in the inner...
Resource Type:: Article

Onshore-offshore variations in copepod community structure off the Oregon coast during the summer upwelling season

Creator:: Morgan, Cheryl A., Peterson, William T., and Emmett, Robert L.
Abstract:: During the summer of 1994, 1996, and 1997, we conducted hydrographic and plankton surveys of the upper 70 m in the nearshore, the continental shelf, and off shelf oceanic waters off Oregon, USA. Copepod densities and biomass were estimated along 4 transects from each cruise. The on shelf copepod biomass...
Resource Type:: Article

Species composition and community structure of pelagic nekton off Oregon and Washington under variable oceanographic conditions

Creator:: Brodeur, Richard D., Fisher, Joseph P., Emmett, Robert L., Morgan, Cheryl A., and Casillas, Ed
Abstract:: Dramatic changes in the physical and biological conditions off Washington and Oregon, USA, have occurred since 1998, including extreme El Niño (warm) and La Niña (cool) years, high and low Columbia River flow years, a major intrusion of subarctic water, and a low oxygen event on the shelf. The occurrence...
Resource Type:: Article

Columbia River plume fronts. II. Distribution, abundance, and feeding ecology of juvenile salmon

Creator:: De Robertis, Alex, Morgan, Cheryl A., Schabetsberger, Robert A., Zabel, Richard W., Brodeur, Richard D., Emmett, Robert L., Knight, Carolyn M., Krutzikowsky, Gregory K., and Casillas, Edmundo
Abstract:: Well-defined fronts develop at the seaward edge of riverine plumes where suspended materials and planktonic organisms are concentrated by convergent water flows. Riverine plume fronts have been hypothesized to be favorable fish habitats because they can lead to localized prey aggregations. We examined the spatial distribution of juvenile Pacific salmonids...
Resource Type:: Article

Nocturnal feeding of Pacific hake and jack mackerel off the mouth of the Columbia River, 1998-2004: implications for juvenile salmon predation

Creator:: Emmett, Robert L. and Krutzikowsky, Gregory K.
Abstract:: Predation by piscivorous marine fishes has been hypothesized to be a primary source of marine mortality for Pacific Northwest juvenile salmon. During the springs and summers of 1998–2004, we collected predator and prey fishes (forage and juvenile salmonids) at the surface at night off the mouth of the Columbia River....
Resource Type:: Article

Recent pre-recruit Pacific hake (Merluccius productus) occurrences in the Northern California Current suggest a northward expansion of their spawning area

Creator:: Phillips, A. Jason, Ralston, Stephen, Brodeur, Richard D., Auth, Toby D., Emmett, Robert L., Johnson, Carrie, and Wespestad, Vidar G.
Abstract:: Coastal Pacific hake (Merluccius productus) are known to spawn in the southern California Bight from January to March, migrate north during late spring and summer to feed off Oregon, Washington, and British Columbia, and then move back to southern California in the fall. Juvenile Pacific hake nursery areas have been...
Resource Type:: Research Paper

The relationships between predatory fish, forage fishes, and juvenile salmonid marine survival off the Columbia River: a simple trophic model analysis

Creator:: Emmett, Robert L. and Sampson, David B.
Abstract:: A trophic model that simulates interactions between a predatory fish (Pacific hake, Merluccius productus), forage fish, and juvenile salmon off the Columbia River was constructed to identify if trophic interactions could account for marine mortality of Columbia River juvenile salmon. The model estimates the number of juvenile salmon that are...
Resource Type:: Research Paper

ScholarsArchive@OSU

Evidence for selective mortality in marine environments: the role of fish migration size, timing, and production type

Biotic and abiotic factors influencing forage fish and pelagic nekton community in the Columbia River plume (USA) throughout the upwelling season 1999–2009

Interannual variability in the Northern California Current food web structure: Changes in energy flow pathways and the role of forage fish, euphausiids, and jellyfish

Large medusae in surface waters of the Northern California Current: variability in relation to environmental conditions

Onshore-offshore variations in copepod community structure off the Oregon coast during the summer upwelling season

Species composition and community structure of pelagic nekton off Oregon and Washington under variable oceanographic conditions

Columbia River plume fronts. II. Distribution, abundance, and feeding ecology of juvenile salmon

Nocturnal feeding of Pacific hake and jack mackerel off the mouth of the Columbia River, 1998-2004: implications for juvenile salmon predation

Recent pre-recruit Pacific hake (Merluccius productus) occurrences in the Northern California Current suggest a northward expansion of their spawning area

The relationships between predatory fish, forage fishes, and juvenile salmonid marine survival off the Columbia River: a simple trophic model analysis

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