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2

FEAST Higher trophic level model

NPZ-B-DLower trophic

level

ROMSPhysical

Oceanography

Economic/ecological model

Climate scenarios

BSIERP Integrated modeling

Observational Data

Nes

ted

mod

els

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Goal• Provide forecasts of future population

trajectories of walleye pollock under anticipated climate warming; complement the vertically-integrated modeling effort

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Projections of Key Environmental Parameters for the Bering Sea: Empirical Downscaling from Global Climate Models

Nick Bond1, Franz Mueter2, Muyin Wang1, Anne Hollowed3, Carol Ladd4 1 Joint Institute for the Study of the Atmosphere and Ocean, UW2 School of Fisheries & Ocean Sciences, UAF3 Alaska Fisheries Science Center, NOAA4 Pacific Marine Environmental Laboratory, NOAA

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PredationSpatial

distribution

BiomassConsumption

ratePrey

composition

Spring conditions (Late) summer conditions

Prey

Timing of ice

retreat

SpringSST

Prey

Summer SST

Wind mixin

gStabilit

y

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Variables considered• Timing of ice retreat

– Date when average ice cover on southeast Bering Sea shelf first decreases below 20% (updated from Mueter et al 2006)

• Spring transition– Proxy for onset of thermal stratification based on change

in SST (NOAA Extended Reconstructed SST, Smith et al. 2008)

• Late summer SST– Mean Jul-Sep SST (NOAA ERSST) over shelf

• Summer wind mixing– Mean May-July wind mixing

(NCEP reanalysis, Kalnay et al. 1996)

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Variables considered (cont’d)• Water column stability

– Mooring 2 observations & proxy based on1-D model estimates

• Predation pressure (1977-2008)– Index of pollock predation based on consumption

rate and average prey composition in early 1990s estimated in Aydin et al (2007)

• Spatial distribution (juveniles, adults)– Anomalies in spatial distribution based on

summer trawl survey (Spatial EOF/PCA)

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Summer Bottom Temperature Parametric Term p-value ---------------------------------------- SLP (Winter) 0.453 SLP (Spring) 0.047 Ice Cover 0.012 Ice Retreat 0.022 Wind Mixing (JJ) 0.926

August Mixed Layer Depth Parametric Terms p-value ----------------------------------------- SLP(Spring) 0.633 Unimak Pass Wind 0.358 Ice Retreat 0.685 SST (May) 0.838 Wind Mixing (JJ) 0.136

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Estimated effects of summer SST & predation on log-recruitment

8.0 8.5 9.0 9.5 10.0 10.5

89

10

11

Summer SST, age-0

log

-re

cru

itme

nt

1000 1500 2000 25008

.59

.09

.51

0.0

11

.0

Predation, age-0

log

-re

cru

itme

nt

R2 =0.44P = 0.001

Prediction interval

Simulate effect of increase in average SST on recruitment at three levels of predation

Low Med High

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0e+0

02e

-05

4e-0

5

Observed recruitment1977-2007

0e+0

02e

-05

4e-0

56e

-05

Simulated recruitment(0.5 C warming)

0e+0

02e

-05

4e-0

56e

-05

8e-0

5

Simulated recruitment(1 C warming)

0 10000 30000 50000

Pro

bab

ility

Age-1 recruitment (millions)

Predicted distribution of pollock recruitment under 0.5oC and 1oC warming (relative to 1977-2001)

Assuming predation equal to 1977-2007 mean (dashed):

With 0.5 oC warming: 10% decline in median R 31% exceed ‘77-’07 average R

With 1 oC warming: 30% decline in median R 19% exceed ‘77-’07 average R

o

o

Median R

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H3: Winners and losers

Piscivorous fish abundance will increase.

Competition with abundant, piscivorous fish will lead to a decline in murres, kittiwakes and fur seals.

Growing populations of humpback and fin whales increasingly will both consume and compete with forage fish (including juvenile pollock) for zooplankton.

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Bering Sea SST (JAS) - B1 Scenario

6

7

8

9

10

11

12

13

14

2000 2010 2020 2030 2040 2050

Mean

SS

T (

JAS

)

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Bering Sea SST (JAS) - A1B Scenario

6

7

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9

10

11

12

13

14

2000 2010 2020 2030 2040 2050

Mean

SS

T (

JAS

)

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Bering Sea SST (JAS) - A2 Scenario

6

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13

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2000 2010 2020 2030 2040 2050

Mean

SS

T (

JAS

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Pollock Recruitment (A1B Scenario)

0

2

4

6

8

10

12

2000 2010 2020 2030 2040 2050

log

(R)

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Number of Model Runs Indicating Collapse

0

2

4

6

8

10

12

14

1 2 3 4 5 6

Decades

2000s 2010s 2020s 2030s 2040s > 2050

Time of collapse based on 6-year running mean of recruitment estimated fromSST (constant predation) falling below 10% of present day median value

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Summary and Next Steps• Late summer/early fall conditions during larval

stage are best predictors of recruitment• Simulations suggest a considerable reduction in

average recruitment of walleye pollock under moderate warming

• Recruitment model will be revisited; potential predictors such as stratification may be added

• All of the sources of uncertainty (model, regional factors, global climate) will be quantified

• Projections will be made available for MSE