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Climate considerations in the management of anadromous fishes in the Pacific Northwest. Nate Mantua JISAO Climate Impacts Group University of Washington NOAA Climate and Living Marine Resources Workshop Pacific Marine Environmental Lab May 14, 2008 Seattle, WA. Outline.
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JISAO Climate Impacts Group
University of Washington
NOAA Climate and Living Marine Resources Workshop Pacific Marine Environmental Lab
May 14, 2008 Seattle, WA
salmon’s life, typically half the
mortality, and nearly all the growth
From Nathan Taylor UBC Fisheries Centre
Millions of adults
spring chinook returns to the Columbia River mouth (1000s)
Alaska pink and sockeye catch (millions)
Conservation concerns over the offspring from the 2002 returns led to a curtailed CA/OR chinook season in 2005, and sharp restrictions in 2006
Persistence forecasts often fail because productivity varies by an order of magnitude…
West-coast sub-arctic habitat is dynamic and sensitive to changing wind patterns (frequently influenced by El Niño and La Niña)
Sept 1997 El Niño
Sept 1998 La Niña
Cool water, weak stratification
high nutrients, a productive “subarctic” food-chain with abundant forage fish and few warm water predators
Warm stratified ocean, few
nutrients, low productivity “subtropical” zooplankton, a lack of forage fish and abundant predators
Typically high NW salmon survival
Typically low NW salmon survival
1st winter at sea
1st spring at sea
A few to ~100 adults in 2nd summer
10’s to 100’s post-smolts early summer
Logerwell et al. 2003, Fish. Oc.
Empirically based models often do a good job “explaining” the past with environmental factors, but errors are generally large in forecast mode
“fish-based forecasts” Jack returns
Harvest & allocation decisions(February-March)
(using SST forecast)
(using obs’d ocean conditions)Coho Forecasting Systems
Oregon coho salmon survival
Coastal Ocean Conditions
Sea surface temperatures
Decreasing Spawning Flows
Increasing Winter Flows