The Bering Sea Is it just a Warmer Barents Sea?

1
The Bering SeaIs it just a Warmer Barents Sea?

• George L. Hunt, Jr.
• University of California, Irvine
• and
• Bernard Megrey
• NOAA Alaska Fisheries Science Center

2
Contents

• Physical Comparison
• Climate and Advective Processes
• Productivity
• Biomass
• Ecosystem Structure

3
The Bering Sea
P. Stabeno, PMEL
4
The Barents Sea
C
H. Loeng G. Ottersen
5
Bering Barents Seas Physical
Parameter SE Bering Sea Barents Sea
Latitude 54-60 N 68-85 N
Area gt 200m (km2) 21.1 x 103 533.2 x 103
Area lt 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
6
Lower Trophic Level Productivity
Bering Sea Bering Sea Bering Sea Barents Sea Barents Sea
Inner Inner Middle Outer Outer Arctic Arctic Atlantic
Tot. Primary Production (g C m -2 y-1) 50-70 50-70 150-175 160 160 lt90 lt90 lt200
New Prod. lt20 lt20 30-50 ? ? lt40 lt40 70-110
Secondary Production 2-6 2-6 8-30 16-50 16-50 1-18 1-18 3-17
Dom. Taxa Diatoms Diatoms Diatoms Phaeocystis Phaeocystis
Sakshaug Walsh 2000
7
(No Transcript)
8
Arctic Oscillation and Pacific Decadal
Oscillation Indices
J. Overland, PMEL
9
Bering Sea Decadal-Scale Surface Advection
Wilderbuer et al., 2002
10
Bering Sea Flatfish Recruitment as a Function of
Destination of Larval Drift
Wilderbuer et al. 2002
11
North Atlantic Oscillation Index
12
Year-class Abundance of Cod
Abundance Low Medium High Cold
years 35 7 1 Warm years 31 14 12
H. Loeng G. Ottersen
13
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 gt 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 0.26
Blanchard et al., 2002 Aydin et al., 2002
14
Productivity Bering Barents Seas
Bering Sea Bering Sea Barents Sea Barents Sea
Taxon P/B (y-1) P P P/B (y-1) P P
Phytoplankton 170 2000 2000 117.73 1765 1765
Copepods 6 330 330 10 500 500
Large Zoops 5.5 242 242 4 67.5 67.5
Forage Fish Herring 0.8 1 - 0.78 - 0.78 1 0.38 1.13 1.24 1.13 1.24
Ad Pollock/ Atlantic Cod 0.5 13.73 13.73 1.2 0.54 0.54
Small Flatfish 0.4 3.67 3.67 1 0.7 0.7
Benthic Infauna 1.37 63.84 63.84 1.5 99 99
Aydin et al., 2002 Blanchard et al., 2002
15
Barents Sea Zooplankton Biomass (g m-2) vs.
Capelin Biomass (tonnes)
ICES CM 2003/AFCM22
16
Barents Sea Model Region
Blanchard et al., 2002
17
(No Transcript)
18
SummaryWhy 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

19
SummaryWhy does the Bering have a pollock
biomass 30X that of cod in the Barents?

• 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

20
1st ANNOUNCEMENTInternational GLOBEC
Symposium Climate Variability andSub-Arctic
Marine Ecosystems Victoria, B.C.CanadaMay
16-20, 2005 Co-sponsorsFisheries and Oceans
CanadaNational Science Foundation, U.S.A.North
Pacific Marine Science Organization (PICES) North
Pacific Research Board