A Climate Angle on Uncertainty in Salmon Recovery Scenarios

Nate Mantua Ph D

Joint Institute for the Study of the Atmosphere and Oceans

University of Washington

Key Points

• Spatial variability: – Complex topography in PS region yields complex

spatial patterns of hydro-climate

• Temporal variability: – Climate and weather variations cause habitat variations

at time scales from days to decades

• Salmon in the future? – Don’t buy into long-term climate predictions!

– Careful considerations of climate uncertainty will help paint more realistic pictures of the true uncertainty in recovery scenarios

The predictable part: seasonal rhythms

Puget Sound Precip

Upwelling winds at 48N

Amphitrite Pt SST

Oct Feb Jun

Oct Feb Jun

Oct Feb Jun Jan May Sep

Insolation

The predictable part: seasonal rhythms

Oct Feb Jun

Skagit

Puyallup

Skokomish

Oct Feb Jun

Oct Feb Jun

Puget Sound Precip

Oct Feb Jun

Why is climate important?

• salmon have successfully colonized and occupied each stream type (snow-melt, runoff, and everything in-between)

– Different stocks employ distinct life history behaviors tuned to the predictable seasonal rhythms

– “stability” and “variability” of seasonal climate and

environmental changes have obviously played a role in shaping salmon behavior at the stock level

Variations on the seasonal rhythms

70 75 80 85 90 95 00

70 75 80 85 90 95 00

70 75 80 85 90 95 00

70 75 80 85 90 95 00

70 75 80 85 90 95 00

70 75 80 85 90 95 00

Monthly Puget Sound Precip

Daily Upwelling winds

Monthly Amphitrite Pt SST Skokomish

Puyallup

Skagit

Upwelling impacts (August 2000)

temperature Chlorophyll

upwelling food webs in our coastal ocean: the California Current

Cool water, weak stratificationhigh nutrients, a productive “subarctic” food-chain with abundant forage fish and few warm water predators

Warm stratified ocean, fewnutrients, low productivity “subtropical” food web, a lack of forage fish and abundant predators

Alaska and PNWsalmon production

are out of phase(Hare et al 1999, Fisheries)

future climate?

TWO STREAMS OF UNCERTAINTY:

1. Natural Variability (El Niño, PDO, other)

2. Anthropogenic change• Future emissions and greenhouse gas

concentrations• Climate system response to increased

concentrations of greenhouse gases• future climate change is now assessed with a

range of models and scenarios …

Uncertainty in future climatePart 1: GG Emissions and concentrations

IPCC Summary for Policymakers 2001

Uncertainty in future climatePart 2: Climate Sensitivity

Tem

pera

ture

Cha

nge

(C)

What might climate change look like in the Northwest?

• We looked at 7 scenarios of future climate from climate models

• Averages of 7 scenarios, compared to 20th century:

– 2F warmer by 2020s

– 4F warmer by 2050s

– slightly wetter

• Winters wetter

• Summers ???

20th century average

Impacts of hydrologic changes

• Less snow, earlier melt means less water in summer – irrigation

– urban uses

– fisheries protection

– energy production

• More water in winter– energy production

– floodingNatural Columbia River flow at the Dalles, OR.

recommendations• Consider climate as a source of habitat

uncertainty– develop recovery scenarios based on past

climate records and/or future scenarios, perhaps bounded by “best” and “worst” cases

• Consider potential roles for stock diversity– explore a range of functional relationships

between habitat state and survival– examine the importance of straying between

different population segments

OPI (hatchery) coho marine survival

0

0.02

0.04

0.06

0.08

0.1

0.12

0.1419

70

1972

1974

1976

1978

1980

1982

1984

1986

1988

1990

1992

1994

1996

1998

Return Year

Surv

ival

Question: WHY?

leading hypothesis: changes in ocean conditions impact the entire marine food-web

“Ocean Conditions Model” hindcasts for 1948-1968

Washington-Oregon-Californiacoho landings

Cat

ch in

mil

lion

s of

coh

o

2

4

6

OP

I survival rate (%)

2

4

6

8

10

Ocean conditions appear to be an important piece of the OPI hatchery coho story; they may or may not explain an important part of 48-68 coho landings.

The Doomsday Clock 2001

Oosterhout and Mundy, 2001

Brood year

Wil

d S

paw

ners

1999 2020

Their approach amounts to a “persistence forecast” based on expectations for continued “non-replacement productivity” observed in the 1985-1994 period

Hatcheries: a fish is a fish

Spring transition date

Mar Apr May June July

Wild coho smolt migration

Hatchery coho releases

Ex: smolt migration timing in wild and hatchery coho

ocean temperature deviations from normalFebruary-April 2002