Ocean Fisheries upwelling

2013 was a spectacular year for marine life in the Monterey Bay due to an unusually huge and prolonged presence of anchovies. Strong wind driven upwelling of cold nutrient rich water along the California coast typically feeds large fish populations in the spring and late summer. But after being scarce in numbers for about five years, what made 2013 so dominated by anchovies?

Superimposed on the normal nutrient upwelling along the coast are climate cycles of varying durations. The climate of the entire Pacific Ocean fluctuates on time periods of roughly 20 to 30 years. The changes are between generally warmer or generally cooler surface water in the northern Pacific and are called the Pacific Decadal Oscillation (PDO).

The PDO is a different, much longer cycle than the El Niño/La Niña (ENSO) cycles. But, the warmer PDO cycle tends to favor El Niño years and good fishing of sardines and barracuda. A cool period in the PDO tends to favor La Niña conditions and anchovies. erey coincided with a warm period of the PDO. In general, the abundance of many species living in the ocean shift in 20 to 30 year cycles due to patterns set up by the PDO.

So lets put theory to practice and see if data for the PDO and ENSO conditions help explain the anchovy blooms of 2013. In fact they generally do. It has been a cold period in the PDO since June of 2010, and ENSO conditions since 2010 have been generally neutral to La Niña. So it looks like large-scale ocean circulation patterns can be used to help explain the presence of the anchovy blooms of 2013.

Time series of shifts in sign of the Pacific Decadal Oscillation (PDO), 1925 to 2013. Image courtesy of NOAA Fisheries.Interestingly, much of the development along the California Coast, including Santa Cruz, took place between the mid-1940s and the mid-1970s, which, we now know, was a three decades-long period of a cool phase in the PDO. In the late 1970s, the stable weather period began to change as the PDO moved to a warm phase and large storms in 1977/78 and 1982/83 coincided with strong El Niño conditions.

The large storms of 1977/78 and 1982/83 led to increased studies of trends in ocean and atmospheric circulation. It will be interesting to see how the current dry period plays out and what increased understanding of the connections between the ocean, climate and ecology will be learned-now that scientists know better what to look for and measure.

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The ENSO Index. Positive anomolies (red) mean El Niño conditions. Negative anomolies (blue) mean La Niña conditions. Image courtesy NOAA.References:

Feeding Frenzy. Mila Zinkova. Earth Science Picture of the Day Website.

EL Niño Southern Oscillation: Cold and Warm Episodes by Season. US National Weather Service Climate Prediction Center. National Oceanic and Atmospheric Administration Website.

Living With the Changing California Coast. Gary B. Griggs, Kiki Patsch, Lauret E. Savoy. University of California Press; 2005.

NOAA Fisheries Website. .

Our Ocean Backyard: Changing climate and shifting species. Gary Griggs. Santa Cruz Sentinel. October 4, 2010.


RFF Press The Common Wealth in Ocean Fisheries: Some Problems of Growth and Economic Allocation (RFF Agriculture and Fisheries Set)
Book (RFF Press)

Pacific NW fishermen are f*cked.

2005-08-09 10:19:47 by armchair

The Pacific Ocean off of Oregon has experienced a die-off of birds, declining fisheries and wildly fluctuating conditions in the past few months, and has set the stage for another hypoxic "dead zone" like those of 2002 and 2004, according to experts at Oregon State University.
This is the third year in the past four that has demonstrated significantly unusual ocean events, the researchers say, a period unlike any on record. The events have not all been the same. This year's ocean behavior is particularly bizarre, and there is no proof what is causing it.
But extreme variability such as this, OSU researchers say, is consistent with what scientists believe will occur as a result of global warming


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