Co-Convenors: Sukyung Kang (Korea), James Overland (U.S.A.), Akihiko Yatsu (Japan) and Skip McKinnell (PICES)

Invited Speakers:
Jürgen Alheit (Leibniz Institute for Baltic Sea Research, Germany)
Emanuele Di Lorenzo (Georgia Institute of Technology, U.S.A.)

The coincidence of multidecadal-scale alternations of dominant marine fish species coupled with multidecadalscale “Climatic Jumps” created a concept of the Regime Shift. The recently published PICES North Pacific Ecosystem Status Report noted that the frequency of these events appears to have increased, and various indicators suggest that their amplitude has increased as well. The Arctic Oscillation Index, for example, reached an extreme negative anomaly during January-March of 2010, which brought a severe winter to much of the Northern Hemisphere, while other areas were warmed equivalently by the effects of the 2009/10 El Niño. The summer of 2010 saw record-setting high temperatures in some PICES member countries, accompanied by an abrupt shift in the tropics from El Niño to La Niña in July 2010. In the northwestern Pacific, after decades at low levels, sardine abundance has begun to increase, while the anchovy abundance is declining; perhaps signaling a new Regime. This session will review recent ocean/climate variability, with emphasis on what has occurred from 2009 to 2010. It will focus on the major ecological components of North Pacific marine ecosystems, particularly commercially important fish species. Papers on mechanistic linkages between population dynamics of marine species and environmental conditions are especially encouraged.