Climate and Pacific salmon ENVIR/ATMS/ESS/SMA 585A April 23, 2009.
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Transcript of Climate and Pacific salmon ENVIR/ATMS/ESS/SMA 585A April 23, 2009.
Outline
the NW salmon crisis Evidence for climate impacts on salmon ENSO and PDO Global warming impacts
The Northwest Salmon Crisis: The Northwest Salmon Crisis: commercial landings in the Columbia River 1863-1993commercial landings in the Columbia River 1863-1993
1950
1920’s
1870’s
19931863
Mill
ions
of
poun
ds la
nded
10
20
30
1988
1977
1911
Why the decline?
The industrial economy+natural variability fur trade, mining, timber harvests,
grazing, irrigation, dams, overfishing, poor hatchery practices, poor management and poor ocean conditions (Lichatowich 1999)
We have reduced opportunities for wild salmon at every stage of their lifecycle (loss of habitat), and we have reduced their capacity for adaptation (loss of
species diversity)
The climate/habitat ratchet(Lawson 1993)
Climate Climate variabilityvariability
Habitat quality and quantity, species diversity
Fish Population
20001900 1950
++
Climate and freshwater habitat issues
Winter floods: scouring incubation period flows, heavy siltation of redds, flushing alevins, fry and parr out of favored habitat
Spring snowmelt freshet: some populations have smolt migrations timed to “ride” the high flows to the ocean
Low summer/fall streamflow+high stream temperature:
Increased stress, diseases and parasites, reduced rearing and spawning habitat, thermal blocks to adult migration
At extreme high temperatures (T > 21°C for prolonged period) salmon die
Ocean conditions and Pacific salmon
A few key points for linking climate to ocean productivity for
salmon
Salmon feed and mature in productive
cool-fresh-nutrient rich subarctic waters from
northern Japan to California -- coastal
upwelling extends this habitat south to S. Cal.
July Sea Surface TemperatureJuly Sea Surface Temperature
SeaWiFS images from NASA’s Goddard Space Flight Centerhttp://seawifs.gsfc.nasa.gov/SEAWIFS.html
July “ocean color”July “ocean color”
Ocean habitat for Pacific salmon and Ocean habitat for Pacific salmon and steelheadsteelhead
Ocean habitat domains are
closely linked to wind and
current patterns
(from Ware and McFarlane, 1989)
UPWELLINGUPWELLING
UPW
EL
LIN
G
UPW
EL
LIN
GDOWNWELLINGDOWNWELLING
DOWNWELLINGDOWNWELLING
Winter windsand pressure over the North Pacific
Summer windsand pressure over the North Pacific
“Aleutian Low” “Subtropical High”
HH
LL
Coastal upwelling
Spring and summer winds from the north cause upwelling of cold, nutrient rich waters into the coastal waters of the western US
Fickle winds can cause large changes in upwelling habitat on short time-space
scales
17.5C on July 1417.5C on July 14
~11C on July 20~11C on July 20
Stonewall Banks Buoy SSTStonewall Banks Buoy SSTJune 18 - August 2 2005June 18 - August 2 2005
20 July 2005 SST NOAA CoastWatch image
Buoy SST plot courtesy of Pete Lawson
June July August
Sept 1997 El Niño Sept 1998 La NiñaSept 1998 La Niña
Year-to-Year changes associated with ENSO variations Year-to-Year changes associated with ENSO variations can also be large -- note the 3 to 4 C decline in coastal can also be large -- note the 3 to 4 C decline in coastal
SSTs between Septembers of 1998 and 1999SSTs between Septembers of 1998 and 1999
17
18
15
13
14
12
“Newport Line” (central Oregon coast)
upper ocean temperatures
Dep
th in
met
ersA thick layer of
warm (low density) water at the surface can cut off the nutrient supply…
Upwelling without nutrients yields no benefits to phytoplankton!
April 1983April avg1962-71
Figure obtained from:http://ltop.coas.oregonstate.edu/~ctd/
An intense An intense Aleutian Low Aleutian Low warms and warms and stratifies the stratifies the coastal oceancoastal ocean
Typical winter winds and jet Typical winter winds and jet stream during El Nino wintersstream during El Nino winters
Cool water, weak stratificationhigh nutrients, a productive “subarcticsubarctic” food-chain with abundant forage fish and few warm water predators
Warm stratified ocean, fewnutrients, low productivity “subtropicalsubtropical” food web, a
lack of forage fish and abundant predators
Recently, warm ocean years have generally been poor for NW chinook, coho and sockeye, but good for Puget Sound pink and chum salmon.
Upwelling food webs in our Upwelling food webs in our coastal oceancoastal ocean
West Coast Nekton in 1997-98
Major changes in the Major changes in the distribution of pelagic distribution of pelagic fishes and squid lead to fishes and squid lead to important “top-down” important “top-down” impacts on coastal food-impacts on coastal food-webs toowebs too
ENSO and salmon habitatEl Niño winters:
intense Aleutian Low low snowpack and streamflow
Weak tropical trade winds, coastally trapped warm water currents
warmed, strongly stratified upper ocean for PNW coast
La Niña winters: weak Aleutian Low,
abundant snowpack and streamflow
intense tropical trade winds, coastally trapped cold water currents
cooled, weakly stratified upper ocean for PNW coast
Decadal variations in spring upwelling
In the 20th C. springtime upwelling winds varied strongly at interdecadal timescales (partly in step with the PDO)
Schwing et al. 2006: GRL
stro
ng
wea
k
Dramatic changes in snowmelt Dramatic changes in snowmelt systemssystems
Snowmelt rivers become transient basins Transient basins become rainfall dominant
Summer base flows are projected to drop Summer base flows are projected to drop substantiallysubstantially (5 to 50%) for most streams in western WA and the Cascades
The duration of the summer low flow season is duration of the summer low flow season is also projected to increase in snowmelt and also projected to increase in snowmelt and transient runoff riverstransient runoff rivers, and this reduces rearing habitat
Models project more winter floodingmore winter flooding in sensitive “transient runoff” river basins that are common in the Cascades
Likely reducing survival rates for incubating eggs and rearing parr
Western Washington’s “maritime” summer climate becomes as warm as today’s interior Columbia
Basin, temperatures in the interior Columbia Basin become as warm as today’s Central Valley in
California
1980s
Thermal stress season
Extended periods with weekly average water temperatures > 21C the season of thermal
migration barriers for migrating salmon predicted to last up to 12 weeks in the mainstem Columbia River
Number of weeks T > 21C
Weeks with T > 21C
IPCC multi-model ensemble SST projections
Under a conservative (A1B) greenhouse gas emissions scenario, climate models typically project 2 to 3 ºC warming by 2090s for the north Pacific
From the Seattle Post-Intelligencer, October 20, 2005
Species distributions change with temperature
134 lb marlin caught 40 mi. west of Westport, WA, Sept 2, 2005
Photo obtained from the Seattle Times web-archives
Global warming and Coastal Cooling?
Because the land warms faster than the ocean, this may intensify the sea level pressure gradient between the oceanic Highoceanic High and Thermal LowThermal Low over land, which would intensify upwelling winds… which would cool the ocean even more, and further increase the temperature contrast
“ThermalLow”Over
Warm land
“OceanicHigh”Over
Cooler water
H L
See Bakun, Patterns in the Ocean, p 223-227
West
coast
West
coast
IPCC multi-model ensemble summer and winter SLP
projections
Taken as a group, IPCC climate models project trends to a stronger North Pacific High in summer, and a deeper Aleutian Low in winter
2090s A1B IPCC models
JJA
DJF
H
H
LL
regional climate modeling results are being analyzed now…
Salathé, Zhang, Mantua, and Mitchell, in prep
2060s -1990s wrf/echam5_A1B
JFM windstress AMJ windstress
In this model, wintertime Aleutian Low and springtime North Pacific High both intensify in late 21st century …
L
• Reduced calcification rates for calcifying (hard-shelled) organisms and physiological stress
• Shifts in phytoplankton diversity and changes in food webs
• Reduced tolerance to other environmental fluctuations
• Potential for changes to fitness and survival, but this is poorly understood
What are the biological implications of What are the biological implications of ocean acidification?ocean acidification?
Barr
ie K
ovis
h
Pacific Salmon
Coccolithophores
Vic
ki F
ab
ry
Pteropods
Copepods
AR
CO
D@
ims.
uaf.
ed
u
(Slide provided by Dick Feely, NOAA)
Cumulative impacts across the full life-cycle of salmon
Early snowmelt;
lower+warmer
summer/fall flows
Floods, warmer temps
Warmer, more stratified, but
upwelling? Acidification?
Warmer, lowerstreamflow
Concluding thoughts Higher temperatures and changes in stream
flow timing will exacerbate existing stresses on salmonids in freshwater and estuaries
Without significant efforts to restore and protect Without significant efforts to restore and protect instream flows, migration corridors, and thermal instream flows, migration corridors, and thermal refugia, climate warming may be the straw that refugia, climate warming may be the straw that breaks the salmon’s back in some (many?) basinsbreaks the salmon’s back in some (many?) basins
Global warming impacts on ocean conditions are now highly uncertain, yet 20th Century observations suggest that many PNW stocks suffer low ocean productivity during periods of warm ocean temperatures
There are clear warming trends in upper ocean There are clear warming trends in upper ocean temperatures in the CCS; trends in upwelling winds are temperatures in the CCS; trends in upwelling winds are less apparent, but will be extremely importantless apparent, but will be extremely important
Temperature tag data from an adult Copper River (Alaska) fall run steelhead,
1998 age 2.3, spawning check at second ocean annulus
Chart provided by Kate Myers, UW FRI
Warmer lower
flows in summe
r
Floods
Acidification, warming,
winds?
Warm, lowstreamflow
Impacts summary for salmonImpacts summary for salmon
The future wont likely present itself in a The future wont likely present itself in a simple, predictable way, as natural simple, predictable way, as natural variations will still be important for variations will still be important for
climate change in any location climate change in any location
Overland and Wang Eos Transactions (2007)
Box1
oC
Deg
rees
C
Warmer lower
flows in summe
r
Floods
Acidification, warming,
winds?
Warm, lowstreamflow
Impacts summary for salmonImpacts summary for salmon
Impacts will vary depending on life history and watershed types
Low flows+warmer water = increased pre-spawn mortality for summer run salmon and steelhead Clear indications for increased stress on
Columbia Basin sockeye, summer steelhead, summer Chinook, also Lake Washington sockeye and Chinook
Mitigating projected impacts
Reduce existing threats caused by land/water use that impair natural hydrologic processes and degrade habitat
– Protect and restore instream flows in summer– Identify and protect thermal refugia– Reconnect, restore and protect off-channel habitat in floodplains
Glines Canyon Dam, Elwha River
Dam Removal can offer some stocks a much brighter future
than the recent past … Marmot Dam, Sandy R.
OR Savage Rapids Dam,
Gold Hill Dam, Rogue R. OR
Klamath R. Dams, CA-OR Elwha Dams, WA Shasta R. Dam, CA Camp Meeker Dam,
Dutch Bill Cr. CA Marmot Dam July 24, 2007
Increased conflict over use of surface water in summer
Human demands on surface water are projected to increase during times of high salmon vulnerability
Planning for a warmer future The potential for increased conflict over
scarce summer water begs for strategic policy thinking that recognizes trade-offs will have to be made
Developing clear decision-guidance now may be an effective way to avoid future crises and potentially high-cost conflicts
The future wont likely present itself in a The future wont likely present itself in a simple, predictable way, as natural simple, predictable way, as natural variations will still be important for variations will still be important for
climate change in any location climate change in any location
Overland and Wang Eos Transactions (2007)
Box1
oC
Deg
rees
C
IPCC multi-model projection for ocean temperatures (A1B emissions)
Latitude-depth cross-section for projected ocean-temperature changes show more surface-intensified warming between 60N-60S, indicating further increases in the stratification of the upper ocean (A1B scenario output shown above)
2011-20302011-2030 2046-20652046-2065 2080-20992080-2099
55yr trends in Pacific SSTs
Since 1950 there has been a near-global warming of SSTs subarctic N. Pacific SSTs have a cooling trendsubarctic N. Pacific SSTs have a cooling trend
(Figure created by Todd Mitchell, UW-JISAO)
Welch et al’s (1998) Welch et al’s (1998) Thermal Thermal LimitsLimits
Key Assumptions:1. Salmon and steelhead are surface
oriented at sea
2. They are metabolically constrained by surface ocean temperatures
3. Surface ocean warming will force salmon (sockeye and steelhead) out of the Pacific and into cooler northern oceans as metabolic rates accelerate with warming