www.elsevier.com/locate/pocean Have there been recent changes in climate? Ask the fish

• Main Authors: Gordon A. Mcfarlane, Jacquelynne R. King, Richard J. Beamish
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Pacific; aleutian low
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.483.2647; http://www.pac.dfo-mpo.gc.ca/science/people-gens/beamish/pdf_files/33.pdf

It is generally accepted that a climate shift occurred about 1977 that affected the dynamics of North Pacific marine ecosystems. Agreement on the possibility of further climate shifts in 1989 and the late 1990s is yet to be achieved. However, there have been changes in the dynamics of key commercial fishes that indicate changes in their environment occurred in the early 1990s, and possibly around 1998. One method of measuring climate change is to observe the dynamics of species that could be affected. Several studies have described decadal-scale changes in North Pacific climate–ocean con-ditions. Generally, these studies focus on a single index. Using principal components analysis, we use a composite index based on three aspects of climate ocean conditions: the Aleutian Low Pressure Index, the Pacific Atmospheric Circulation Index and the Pacific Interdecadal Oscillation Index. We link this composite index (Atmospheric Forcing Index) to decadal-scale changes in British Columbia salmon and other fish populations. Around 1989 there was a change from intense Aleutian Lows (above average south-westerly and westerly circulation patterns and warming of coastal sea surface temperatures) to average Aleutian Lows (less