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Ric Brodeur

- Research -



Artwork Jessica Nord 2004

As a team leader in the Estuarine and Ocean Ecology Program of the Northwest Fisheries Science Center, I have been involved with studies examining the habitat and ecology of juvenile salmon when they first enter the ocean.  Mortality appears to increase dramatically in the first few months at sea and we still don't know the mechanisms behind these losses. On a short "sabbatical" to a laboratory down in California in 1998, I worked on a coast-wide research plan to examine survival of juvenile salmon in the ocean. Presently, I am working as part of a team that goes out and samples juvenile salmon in large trawls from the Canadian border to northern California. We are comparing our results to those observed during the early 1980s as part of a project under the direction of Bill Pearcy at Oregon State University. My specific interests lie in the food resource utilization of juvenile salmon, particularly in the selection of prey and effects on prey resources (see Food Web Studies).

- Salmon research -

 

 

-Pelagic nekton studies-

 

As part of our research funded by GLOBEC and BPA, I and my collaborators have been examining interannual and longer-term studies of pelagic nekton and micronekton communities off of Oregon and throughout the North Pacific. Nekton are defined as the fast moving, generally larger fishes and squids that are usually caught in pelagic (near-surface zone) trawls.  These include the tunas, salmon, mackerels, herring and smelts, anchovies and sardines, and a large number of other important species. Micronekton are usually smaller and require special sampling nets to capture them. They often include interesting fishes, squid and crustaceans that inhabit the open oceans such as laternfishes, but also can include juvenile fishes. We have attempted to use multivariate statistical methods to define communities and then relate these to oceanographic conditions in which the communities were caught and look at long term changes in dominant species in relation to interdecadal changes in the environment. We also can look at potential predation or competition among the members of a community by examining their diets (see Food Web studies).

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I have been involved in examining food web relationships in the Subarctic Pacific, Bering Sea and along the west coast of the United States for the past 20 years. For my Master's thesis, I examined the feeding ecology of five species of rockfishes over much of the coastal Pacific Northwest, but particularly on their reliance on mesopelagic prey advected onto an offshore bank. I continued on examining the feeding and food web relationships of juvenile salmon in coastal waters, looking at diet overlap with other nekton and food consumption in relation to available prey resources. Many of these studies formed the bulk of my dissertation research. Moving on to work on recruitment studies in walleye pollock, I continued studies of the feeding ecology of this species in both the Gulf of Alaska and Bering Sea. I examined prey selection, diel feeding chronology and food consumption, and variability in feeding with respect to physical factors such as fronts and eddies. Returning to the West Coast, I continue to examine the feeding ecology of juvenile salmon and other associated species by means of stomach analyses and stable isotope ratios through our BPA and GLOBEC funded projects. I also am interested in the effects of abrupt topography in the form of banks or canyons as areas that concentrate prey organisms for higher trophic levels such as rockfishes and have worked in Pribilof Canyon in the Bering Sea, Astoria Canyon and Heceta Bank off Oregon. My work in Astoria Canyon has been particularly interesting as we documented the first occurrence of a mass mortality of krill in the deep ocean as part of our Ocean Exploration program.

- Food web studies -

 

(stomach of an adult chinook salmon

 full of Dungeness crab larvae)

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- Recruitment studies -

 

I have been involved with examining factors underlying recruitment variations in marine fishes for much of my career. Early on, I examined variability in juvenile salmon survival in the coastal ocean related to food availability, growth, and predators. While working with the Fisheries Oceanography Coordinated Investigations in Seattle, I was involved with a long-term study of factors related to year-class strength in walleye pollock in the Gulf of Alaska and Bering Sea. I examined distribution of eggs, larvae, and early juveniles in relation to ocean features such as eddies and fronts. I also was interested in other species that may interact with pollock as competitors or predators in this region. I used immunoassays and gut content analyses to examine vertebrate and invertebrate predation on pollock eggs and larvae, and also conducted controlled laboratory studies on predation. Since moving back to the west coast, I have continued to look at recruitment in juvenile salmon, and am now starting to analyze the full range of ichthyoplankton taxa off the coast to understand recruitment processes in non-salmonid species.

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