March 24, 2020 — The following was released by NOAA Fisheries:
A new study shows that two important indicators for understanding and predicting the effects of climate variability on eastern North Pacific marine ecosystems are less reliable than they were historically. This finding has important implications for fisheries and ecosystem management from Alaska to California.
Until recently, oceanographers and fishery biologists summarized and understood complex and
long-term relationships between regional fish stock productivity and ocean climate patterns using the Pacific Decadal Oscillation index (PDO) and the North Pacific Gyre Oscillation (NPGO).
The PDO accurately described the climate pattern north of 38 degrees N, and the NPGO described the pattern S of 38 degrees N. These two indices captured climate patterns that dominated North Pacific ecosystems for much of the 20th century.
“We were able use these indices to describe changes in collective environmental features including sea surface temperature, sea surface height, sea level pressure, salinity, chlorophyll-a, and ocean nutrients. They also helped us understand and predict changes in the productivity of species like plankton and fish that are sensitive to long-term weather patterns without having to understand specific relationships between individual species and their environment,” said Mike Litzow, NOAA fisheries oceanographer and study lead. “We could count on these indices as reliable tools to summarize this broad suite of climate-biology-relationships.”