Presentation on theme: "Columbia River basin juvenile salmonids : survival in the Columbia River Plume and northern California Current, a decade of observations of ocean conditions."— Presentation transcript:
Columbia River basin juvenile salmonids : survival in the Columbia River Plume and northern California Current, a decade of observations of ocean conditions Ocean Ecology Group at NOAA-Fisheries and the NOAA/Oregon State University Cooperative Institute for Marine Resource Studies
Chinook and coho salmon Climate and salmon survival Habitat requirements –where do salmon live? –which variables might be useful for prediction of returns? –what it is about ocean conditions that affects salmon growth and survival? Some indicators which predict salmon returns
Winds and current structure off Oregon and Washington: Winter: Winds from the South Downwelling Poleward-flowing Davidson Current Uniform cross-shelf hydrography Spring Transition in April/May Summer: Strong winds from the North Coastal upwelling Equatorward alongshore transport Strong cross-shelf physical gradients Upwelling-favorable winds cease in September/October 42° N 43° N 44° N 45° N 46° N Newport WA OR 42° N 43° N 44° N 45° N 46° N Newport WA OR Summer: Winter:
Plankton, Salmon and Pelagic Fish Sampling Sample in May off CR and WB; June and September (all ~ 50 stations; since 1998 Sample Columbia River and Willapa every 10 days from April through July (AT NIGHT) at ~ 10 stations; since 1998 Sample off Newport every two weeks since 1996
PDO Time Series Cool phase 1947-1976 Warm phase 1977-1998 Cool phase 1999-2002 Warm phase 2002-2005 Cool phase 2006 ?? Phase shifts are tracked by the Pacific Decadal Oscillation (PDO): negative values = cool phase; positive values = warm phase. 1970s1980s1999-2002 NORTH PACIFIC SST
The PDO and salmon survival appear to be related Coho and Spring Chinook react somewhat similarly (but the difference in the rebound in 2002 is striking!)
Cool Phase A working mechanistic hypothesis: source waters... Transport of cold water, phytoplankton and boreal zooplankton into the NCC from Gulf of Alaska Transport of warm water, phytoplankton and sub-tropical zooplankton into NCC from offshore and from the south Warm Phase
Comparisons in size and chemical composition of zooplankton Cold water zooplankton species from the Gulf of Alaska are large in size and store wax esters because the hibernate during winter months Warm water zooplankton species from offshore and/or south of Oregon are associated with positive PDO - they are small in size and have very low amounts of high energy wax ester lipid depots Which food chain would you prefer if you were a salmon, especially knowing that you have to face a long winter? Therefore, it is possible that significantly different food chains may result from climate shifts
Salmon and Pelagic Fish Sampling Sample in June and September at ~ 50 stations since 1998 Distribution & abundance Habitat area Growth Stock origin using genetics Diseases and parasites Food habits Otoliths Compare everything to ocean conditions
Can use ocean color as measured by satellites to estimate habitat area We have just begun to test the idea that habitat area throughout the summer is related to SARs.
Why are fish most abundant off WA? What we do know: Stratification weaker Upwelling weaker Broad shelf weak circulation Euphausiids more abundant there What we dont know: Fish prey more abundant there? Submarine canyons concentrate prey? Fish like low salinity water of the plume & Juan de Fuca?
Indicators and Predictions Since coho and Chinook seem to react in the same way to ocean conditions during at least their first few months at sea, suggests that survival may be set during their first summer at sea Can see (next) that catches in our trawl surveys are proportional to each other and are related to survival data
Coho and Chinook caught on June trawl surveys Note: June 2005 produced the fewest coho and Chinook since our surveys began, in 1998
Are low catches in 2005 significant? YES! Because catches in June surveys are correlated with returns two years later. NOTE: 2001 low catches and low returns (in 2003). 01 a year of very low flows in June and low habitat area. 02
Coho catch in June is not related to survival In September, catch is related to survival Ocean conditions experienced by juvenile coho during their first summer at sea appear to influence overall salmon survivorship. Note low catch and low returns for coho that went to sea in 04. Can we expect spring Chinook to be low in 06 as well?? 1998 – 2004 Coho Catches off OR and WA
PREDICTIONS? Spring Chinook returns correlated with a food chain indicator of ocean conditions, with a two year lag Columbia River coho returns correlated with the same indicator but with one year lag Ocean Entry 2005
Salmon and Marine Ecosystems We are at a point where we are able to provide predictions of returns of adult coho one year in advance and Spring Chinook two years in advance. Should help BPA evaluate both their freshwater habitat restoration programs and the role of river flow in spring in affecting salmon survival. Information used by NMFS Regional Office in Seattle to evaluate status of spring Chinook and coho stocks Working on a Northern California Current ecosystem status report which should be of interest to managers in the Pacific Northwest. 2005 report available now. Will be posted to web soon.
WRAP UP Local waters respond to basin-scale forcing, be it ENSO or PDO Climate and hydrographic changes result in two different coastal ecosystems: –A cold water ecosystem which is sub-arctic in origin. Salmon survival is high when the spring transition and upwelling are early, waters are cold, and copepods are lipid-rich. We think predation is also lower during such times. –A warm water ecosystems are sub-tropical in origin. The spring transition and upwelling are late, the food chain is fat-free, predation high, and salmon do poorly.
Coho jacks vs. OPI returns 2006 returns predicted to be 2.2% by Jacks 2006 returns predicted to be < 1% based on catches on our September 2005 survey 2006 returns predicted top be < 1% based on zooplankton food chain indicators
Third Index: SPRING TRANSITION Hydrographic Transition Copepod community structure Transition point Sea level and copepod community structure changes
Spring Transition: hydrography Hydro data only for 97-04 Suggestion that early transition results in higher salmon survival.
Spring Transition: Copepods The physical spring transition occurs on that day when sea level drops and upwelling begins. Biological spring transition occurs on that day when the biology changes from winter to summer. Determined from cluster analysis Transition was very late in 2005; prediction for 2006 are for returns < 1%
Coho jacks vs Northern copepod biomass anomalies Copepod species data can provide a predictor of jack returns by early October, a few months before jack returns are available. Does suggest that survival is set in first summer F = 5.9, p = 0.014 R 2 = 0.38 R 2 = 0.36