The Bering SeaIs it just a Warmer Barents Sea?

George L. Hunt, Jr.University of California, Irvine

and

Bernard MegreyNOAA Alaska Fisheries Science Center

Contents

• Physical Comparison

• Climate and Advective Processes

• Productivity

• Biomass

• Ecosystem Structure

P. Stabeno, PMEL

The Bering Sea

The Barents Sea°C

H. Loeng & G. Ottersen

Bering & Barents Seas: Physical

ParameterSE Bering

SeaBarents Sea

Latitude 54-60 °N 68-85 °N

Area > 200m (km2) 21.1 x 103 533.2 x 103

Area < 200m (km2)

Advection

463.4 x 103

~1 Sv

472.9 x 103

~4 Sv

Nitrate (mM m-3) 10-30 10 -12

Phosphate (mM m-3) 1.0-2.0 0.85

Silicate (mM m-3) 25-60 6-8

Data from: Dommasnes et al., 2001; Sakshaug and Walsh, 2000; Aydin et al., 2002; ACIA, In Press

Lower Trophic Level Productivity

Bering Sea Barents Sea

Inner Middle Outer Arctic Atlantic

Tot. Primary Production

(g C m -2 y-1)50-70 150-175 160 <90 <200

New Prod. <20 30-50 ? <40 70-110

Secondary Production

2-6 8-30 16-50 1-18 3-17

Dom. Taxa Diatoms Phaeocystis

Sakshaug & Walsh 2000

Arctic Oscillation and Pacific Decadal Oscillation Indices

J. Overland, PMEL

Bering Sea: Decadal-Scale Surface Advection

Wilderbuer et al., 2002

Bering Sea Flatfish Recruitment as a Function of Destination of Larval Drift

Wilderbuer et al. 2002

North Atlantic Oscillation Index

Abundance Low Medium High

Cold years 35% 7% 1%

Warm years 31% 14% 12%

Year-class Abundance of Cod

H. Loeng & G. Ottersen

Bering and Barents Seas- Biomass (tonnes km-2)

Taxon Barents 1990 high capelin

Barents 1995 low capelin

E. Bering Sea 1980s

Phytoplankton

Crust. Zoops.20

58

20

58

11.8

26

Capelin

Herring 4.17

1.34

0.14

3.33

-

0.78

Benthic Crust. 1.43 1.38 > 2.2

Flatfish 1.1 1.1 11.3

Gadids 1.2 2.6 35.9

Pinnipeds 0.87 0.87 0.22

Whales 0.20 0.20 0.26Blanchard et al., 2002; Aydin et al., 2002

Productivity: Bering & Barents SeasBering Sea Barents Sea

Taxon P/B (y-1) P P/B (y-1) P

Phytoplankton 170 2000 117.73 1765

Copepods 6 330 10 500

Large Zoops 5.5 242 4 67.5

Forage Fish Herring

0.8

1

-

0.78

1

0.38

1.13

1.24

Ad Pollock/ Atlantic Cod

0.5

13.73 1.2 0.54

Small Flatfish 0.4 3.67 1 0.7

Benthic Infauna

1.37 63.84 1.5 99

Aydin et al., 2002; Blanchard et al., 2002

Barents Sea: Zooplankton Biomass (g m-2) vs. Capelin Biomass (tonnes)

ICES CM 2003/AFCM:22

Barents Sea Model Region

Blanchard et al., 2002

Summary

Why does the Bering have a pollock

biomass 30X that of cod in the Barents?

• Nutrients & Primary Prod similar • Bering -Diatoms, Barents- Phaeocystis

(Sakshaug & Walsh)

• Bering & Barents Sensitive to Timing of Bloom

• Zooplankton more abundant and productive in Bering

• Pollock eat zooplankton- lower trophic level (3.3 vs 4.3)

• Forage fish essential for cod; More (capelin) in Barents;

• Pollock cannibalistic- do not need forage fish

• Pollock 25X more productive • More seals in Barents Sea

Summary

Why does the Bering have a pollock

biomass 30X that of cod in the Barents?

1st ANNOUNCEMENTInternational GLOBEC

Symposium

Climate Variability andSub-Arctic Marine Ecosystems

 Victoria, B.C.Canada

May 16-20, 2005 Co-sponsors:

Fisheries and Oceans CanadaNational Science Foundation, U.S.A.

North Pacific Marine Science Organization (PICES)North Pacific Research Board