Synthesis Workshop Summary The Climate-Ocean Regime Shift Hypothesis of the Steller Sea Lion Decline December 4-5, 2003 Newport Beach, CA 11 Proposals funded by NOAA OAR/NOS CIFAR Object: Synthesis Review Paper of the Research Results Relate temporal variability in the physical system to the ecosystem changes

Workshop Participants Funded Investigators: M. Alexander, A. Capotondi (CDC) S. Bograd (PFEL) K. Coyle (UAF) B. Finney (UAF) G. Hunt, J. Jahncke (UCI) N. Kachel (PMEL) N. Mantua, C. Marzban (UW) H. Maschner (Idaho State) W. Maslowski (NPS) A. Miller, D. Neilson, E. Di Lorenzo, H.-J. Kim (Scripps) S. Okkonen (UAF) T. Royer, C. Grosch (ODU) A. Trites, E. Gregr (UBC) J. Wang (ARL) Program Manager: J. Calder (NOAA) Invited Contributors: L. Fritz (NMFS) J. Overland (PMEL)

Synthesis Paper Highlights Title: The Climate-Ocean Regime Shift Hypothesis of the Steller Sea Lion Decline Forum: Fisheries Oceanography Authors: Trites, Maschner and all contributors Thesis: Spatial and temporal variations in the ocean climate system are creating adaptive opportunities for high trophic levels which is the underlying mechanism for the decline of the Steller sea lion populations in the western Gulf of Alaska. Important results: Temporal issue s to 1990s changes Spatial issue - East vs west asymmetry in Gulf of Alaska Biogeographic transition point at 170W Basin-scale climate changes have regionally sensitive impacts Upscaling from local complexities to broadscale regularities Eddy variance changes in western Gulf

Outline The Climate-Ocean Regime Shift Hypothesis of the Steller Sea Lion Decline Physical Ocean-Atmosphere Data Analysis Ocean Model Results: Coarse and Eddy-Permitting Bio-Geography: Samalga Pass Transition Point Paleo-Perspective: Isotopes and Archeology

Outline The Climate-Ocean Regime Shift Hypothesis of the Steller Sea Lion Decline Physical Ocean-Atmosphere Data Analysis Ocean Model Results: Coarse and Eddy-Permitting Bio-Geography: Samalga Pass Transition Point Paleo-Perspective: Isotopes and Archeology

Analysis of COADS SST, SST clusters into 5 dynamic regions regional differences in long-term SST behavior in eastern Subarctic Pacific Bograd et al., 2004 Sea Surface Temperature Trends in the Gulf of Alaska

Nonlinear PCA results from Marzan, Mantua, and Hare: based on 22 abiotic indices from the Pacific for NL PC1: 32% of variance NL PC2: 23% of variance

Peterson and Schwing, 2003 SSTA SLPA, WindA “cool”“warm”“cool?” North Pacific Regime Shifts: State Changes in Forcing

Modeled Gulf of Alaska coastal discharge Royer and Grosch

Changes in Ekman pumping Capotondi et al. Pre-shift mean conditions Dec-May Change after shift ( ) -( )

Outline The Climate-Ocean Regime Shift Hypothesis of the Steller Sea Lion Decline Physical Ocean-Atmosphere Data Analysis Ocean Model Results: Coarse and Eddy-Permitting Bio-Geography: Samalga Pass Transition Point Paleo-Perspective: Isotopes and Archeology

Pycnocline (26.4   ) depth changes Period2 (77-97) – Period1 (64-75) P = OWS P G = GAK1 Capotondi et al. Model vs. Obs PAPA Model vs. Obs GAK

Before Shift After Shift Difference - More eddies north of Kodiak - Fewer eddies southwards Kodiak Is. Eddy-Permitting Model Eddy Surface Currents Miller et al.

NPS Model SST along shelf break Deep Salinity along shelf break Okkonen et al. Naval Postgraduate School numerical model 23 year ( ) simulation with real winds

Physical-Biological Ocean Hindcast (Chai et al. model) Decrease in large zooplankton (and large phyto, small zoo) after the shift… …But occurs only during spring bloom Alexander et al.

Outline The Climate-Ocean Regime Shift Hypothesis of the Steller Sea Lion Decline Physical Ocean-Atmosphere Data Analysis Ocean Model Results: Coarse and Eddy-Permitting Bio-Geography: Samalga Pass Transition Point Paleo-Perspective: Isotopes and Archeology

Locations of Passes sampled May-June 2002 Coyle et al. Samalga Pass forms a boundary between shelf water to the east and open ocean waters to the west

Surface Salinity along Aleutian Islands Ladd et al. (2004) East of Samalga Pass, ACC has strong influence West of Samalga Pass, Alaska Stream has strong influence

Coyle et al. Abundance vs. Transect May-June 2002

Short-tailed shearwaters Northern fulmars Tufted puffins Small alcids Jahncke et al. West of Samalga Pass: Fulmars and Auklets (open ocean food web) dominant East of Samalga Pass: Shearwaters and Puffins (coastal food web) dominant Seabirds Reflect Biogeographical Boundaries

Outline The Climate-Ocean Regime Shift Hypothesis of the Steller Sea Lion Decline Physical Ocean-Atmosphere Data Analysis Ocean Model Results: Coarse and Eddy-Permitting Bio-Geography: Samalga Pass Transition Point Paleo-Perspective: Isotopes and Archeology

Paleoproductivity  13 C Opal (%) Gulf of Alaska: GAK 4 Core Year AD Opal (%)  13 C Opal (%) GOA GAK 4 Skan Bay  13 C Bering Sea: Skan Bay Core Paleoproductivity > 1976 Regime-shift Bering Sea:  13 C - decrease Opal - variable Gulf of Alaska:  13 C - increase Opal - increase Finney et al.

Relative Abundance of SSL based on Archaeological Data Maschner et al.

Some Outstanding Questions The Climate-Ocean Regime Shift Hypothesis of the Steller Sea Lion Decline What mechanisms control the restructuring of the ecosystem by climate, especially concerning fish? How do human activities and ecosystem interactions work with variable climate forcing to alter Steller sea lion populations? Do Steller sea lions feed in eddies? What can be said about changes in sub-surface conditions? How does vertical mixing vary in space and time? What other regime shifts may have occurred?

Synthesis Paper Highlights Title: The Climate-Ocean Regime Shift Hypothesis of the Steller Sea Lion Decline Forum: Fisheries Oceanography Authors: Trites, Maschner and all contributors Thesis: Spatial and temporal variations in the ocean climate system are creating adaptive opportunities for high trophic levels which is the underlying mechanism for the decline of the Steller sea lion populations in the western Gulf of Alaska. Important results: Temporal issue s to 1990s changes Spatial issue - East vs west asymmetry in Gulf of Alaska Biogeographic transition point at 170W Basin-scale climate changes have regionally sensitive impacts Upscaling from local complexities to broadscale regularities Eddy variance changes in western Gulf

Extras

(a) trend 1 loadings increase west to east warming from early 70’s accelerated warming after 76 (b) trend 2 accentuates trend 1 pronounced drop after 58 rapid rise after 72 positive loadings = strong warming after 72 (c) trend 3 strong warming in eastern GOA during event broad warming after 76 (d) trend 4 strong interannual variability impacts from El Niño events strong loadings in coastal BC and WWD Bograd et al., 2004 Sea Surface Temperature Trends in the Gulf of Alaska

Nonlinear PCA results from Marzan, Mantua, and Hare: based on 45 biotic indices from the Bering Sea and Gulf of Alaska for NL PC1: 39% of variance NL PC2: 18% of variance

Kendall’s  trends in Alaska adult SSL data (Marzban, Mantua and Hare) 99% ci -- For SSL data from

Seasonal Amplitude and Phase Changes in Coastal Freshwater Discharge Royer and Grosch

Wavelet Analysis of Coastal Freshwater Discharge Royer and Grosch

Naval Postgraduate School numerical model 23 year ( ) simulation with real winds Okkonen et al. Red line indicates shelf break (for Hovmuller diagram)

Coyle et al. T and S vs. Transect May – June 2002

Schematic of Traditional Aleut Knowledge of Recent North Pacific Cycles Maschner et al.