Climate and Pacific salmon

ENVIR/ATMS/ESS/SMA 585AApril 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

++

Estuaries!

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/

Warm extremesEl Niño

cold extremesLa Niña

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

Coastally trapped internal waves from the tropics

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

Alaska and PNWsalmon production

see-saw(Hare et al 1999, Fisheries)

Global Warming Impacts on freshwater habitat

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

Back to the Pacific

will global warming degrade marine habitat for salmon?

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

Sockeye salmon Sockeye salmon distributiondistribution

(Welch et al (Welch et al 1998)1998)

December

July

20th Century20th Century

distributiondistribution

2xCO22xCO2

distributiondistribution