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Surprising Science

How Wayward Tuna Help Forecasters Predict El Niño

When water warms in the tropical Pacific Ocean, different types of tuna will migrate into the waters near San Diego. Keeping track of a fisherman’s catch can help meteorologists predict the severity of an oncoming El Niño.

What’s the Latest?

Forecasters are pretty dead set on this being an El Niño year. While meteorologists have many ways to measure and predict the extreme weather phenomenon, there’s one method in particular readers may find somewhat fishy. Tim Barnett, marine research physicist emeritus with Scripps Institution of Oceanography, says the secret to judging the potential impact of an El Niño is in tuna. That’s right, tuna:

Barnett said the ’97-’98 event caused a northward shift of the whole fishery population, drawing an abundance of albacore and Bluefin tuna to San Diego’s unusually warm waters.

“We’ve already started to see very unusual fish catches here,” Barnett said. “The first yellowfin tuna was caught in May — that has never happened before to anybody’s recollection.”

What’s the Big Idea?

Barnett explains that when an El Niño warms the the tropical Pacific, fish that aren’t native to the waters around San Diego tend to appear there as early as May. Some species get carried even farther north. In 1997, another El Niño year, fishermen in Kodiak, Alaska were dumbfounded when they pulled yellowtail tuna out from the sea. That type of fish is so rare in those parts that the fishermen actually had to send their catches down to California to have them identified. While it’s still early to determine just how large-scale this year’s El Niño will be, Barnett sees the wayward fish as a foreboding omen for a wet and wild summer.

Read more at KPBS

Photo credit: SOMKKU /


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