Sub-decadal oceanic oscillations regulate the north-eastern Atlantic shelf ecosystems

1. -3 Chl [mg m ] SeaWiFS-based chlorophyll in selekt Blue whiting Sub-decadal oceanic oscillations regulate the north-eastern Atlantic shelf ecosystems Sub-decadal oceanic oscillations and blue whiting recruitment Hjálmar Hátún, Payne, M., Sandø, A. and others... Santander, 2011

2. Outline • The subpolar gyre – marine climate link and blue whiting stock dynamics • Can we predict recruitment? • some new ideas on the sub-decadal variability.

3. 1. The Subpolar Gyre and themarine climate Subtropical Gyre Subpolar Gyre Labrador Sea convection (Hatun et al., Science 2005)

4. 1. The Subpolar Gyre and the marine climate I R Weak. Salinity at Rockall (obs.) Salinity in the Irminger Current (obs.) Strong Record high T and S Gyre index (GI)

5. 1. The Subpolar Gyre and the marine climate Warm Cold Simulated temperature Large mid-1990s changes!

6. Herring Mackerel Spawning Blue whiting: Spawning-feeding distributions/migrations Feeding Blue whiting

7. Largest fishery in the North Atlantic! A threefold blue whiting stock size increase Stor endringer i kolmule bestanden SST (in Rockall Areal) Stock size (<- shifted 3 years)

8. 1997 Cold (1990-1996) Warm (1998-2003) Post-spawning migration: (Hátún et al. 2009, PIO) Spawning distribution: (Hátún et al. 2009, CJFAS) Spatial Shift (Blue whiting catches – all nations)

9. So what about blue whiting recruitment?

10. Need to understand the processes North Atlantic Sub-polar gyre Atmospheric forcing Gyre index and recruitment not significantly correlated Recruitment (Payne et al., 2011, In Press)

11. 2. Atmosphere-gyre details Curl (ws) [N/m ] 2 0 Wind stress curl Green- land Wind stress (ws) - arrows (NCAR/NCEP) Cyclonic (Curl >0) UK Anticyclonic (Curl <0)

12. 2. Atmosphere-gyre details Subpolar Gyre WSC = 0 Subtropical Gyre

13. 2. Atmosphere-gyre details Subpolar Gyre ’Window’ ”Inter-gyre region” WSC = 0 Subtropical Gyre

14. 2. Atmosphere-gyre details ”Inter-gyre region” Subpolar Gyre ’Navidad’

15. 2. Recruitment Recruitment and wind stress curl Recruitment R Vs. WSC Spain

16. Recruitment and windstress curl

17. Recruitment and windstress curl Improved Recruitment? Northwardtransport

18. 3. Monitoring with altimetry Sea surface heightand marine climate Warmer

19. 3. Monitoring with altimetry Gyre Mode Time series (gyre index) Spatial pattern (Updated from Hakkinen and Rhines, 2004)

20. 3. Monitoring with altimetry Transport anomalies of source waters Eastern source ~ 7 Sv (Pingree, 2002) Western source

21. 2. Hydrographic Pulses Decompose onto a S-axis An along-Continental Slope perspective (Data availability) Porcupine (Hátún et al. 2009, CJFAS)

22. 2. Hydrographic Pulses Salinity Salinity @ 300m Shetland Porcupine

23. 2. Hydrographic Pulses Salinity, currents Salinity @ 300m Shetland Weaker NAC Porcupine

24. 2. Hydrographic Pulses Salinity, currents and recruitment Salinity @ 300m Shetland A new boom? Porcupine

25. So is the recruitment predictable? Not with certainty - But certainly not if the marine climate is ignored I ’predict’ that the 2009 year-class will be strong 

27. 3. Monitoring with altimetry Transport anomalies of source waters

28. 3. Monitoring with altimetry Transport anomalies of source waters and blue whiting recruitment

29. 2. Recruitment Salt-pulses and blue whiting recruitment Shetland Porcupine

30. So what about recruitment? Bad recruitment Good recruitment (Hátún et al., 2009, CJFAS)