Scientist Talks The Appearance Of Japanese Sardines Off The California Coast
Really cool podcast interview from NOAA Fisheries West Coast with Dr. Gary Longo, who talks about the discovery of Japanese sardines far east of Japan off the California coast.
Here’s more from NOAA:
Japanese Sardines in California? A Shocking Discovery in the Pacific
March 13, 2025
We hear from the scientist who discovered Japanese sardines off the coast of California for the first time and discuss what it means for the future.
In 2022, Dr. Gary Longo detected Japanese sardines swimming in the eastern Pacific, off the coast of California. This was the first time they’d ever been seen here—their normal range is in the western Pacific from Korea to Russia, thousands and thousands of miles away. It was a shocking discovery. Sardines are incredibly important to the California current ecosystem and are a key forage fish across the globe.
On this episode of Dive In with NOAA Fisheries, we scratch at this mystery of Japanese sardine appearing in U.S. waters. How did they get here? What does it mean for the native Pacific sardine? Are they staying? (Spoiler alert: so far, yes.)
We hear from Dr. Longo, a research scientist at NOAA’s Southwest Fisheries Science Center and one of the authors of a new study documenting this discovery. The authors suggest marine heatwaves that warmed the North Pacific over the last decade might have opened a corridor of favorable habitat, which the Japanese sardines followed across the ocean.
You can listen to the full podcast here. And this is sample of what Dr. Longo had to say via the transcript:
0:02:24.4 JS: So you said it was pretty shocking. And for a little background on Pacific sardines off the West Coast, sardines are a big deal in California. Can you give us a little context on just how much of a staple fishery it is?
0:02:40.2 GL: Sure. Well, historically, Pacific sardine from the 1920s to the 1940s represented the largest fishery on the West Coast of the US with a peak catch of around 700,000 metric tons. But following the 1940s, there was a pretty dramatic crash, and there wasn’t much of a fishery until the 1980s when numbers started to rebound. But numbers never really rebounded to the numbers we saw in the 1920s and ’40s. And again, the numbers began to decline in the early 2000s, and in 2015, the fishery was closed and has been closed since then.
0:03:18.8 JS: Yeah. And it is also a forage fish. This is something that, it’s a species that is observed carefully.
0:03:28.2 GL: Correct. Yeah. So ecologically, outside of, you know, obviously being part of the National Marine Fishery Service, we’re interested in fishes that are federally managed. But outside of that, ecologically, sardine are incredibly important to the California current ecosystem and whatever ecosystem they occur in, they are eaten by many, many things and allow a transfer from energy from phytoplankton to higher up in the food chain.
0:03:54.1 JS: So do we know how these Japanese sardines showed up on the West Coast? I mean, it’s probably hard to pin down an exact reason, but are there theories?
0:04:02.6 GL: Yeah, we have some theories. We don’t… We, like you said, we don’t know for sure how they managed to cross the North Pacific and get over here. But there’s a couple things that are at play. One thing is that you may have heard, but there’s been some recent warming trends on planet Earth. And Japanese sardine are found in the western Pacific in temperate waters. Pacific sardine are in the eastern Pacific. And so we have really, really cold water up north in the Arctic and warm water down near the equator that have really acted as kind of dispersal barriers to keep these two species separated over hundreds of thousands of years. However, as things have warmed up in the Arctic, it appears that some of those dispersal barriers, in other words, that cold water, has warmed up enough that there may have been a potential habitat corridor that opened up and allowed for Japanese sardine to expand into that warmer water, which is now in a threshold where they can survive. And another important factor is that sardine, like many coastal pelagic species, during times of abundance, their range will expand. So Japanese sardines have gone through similar cycles of crashing and growing.
