When research scientist Gary Longo first saw the results of his genomic analysis of sardines, he thought he must have mixed up his samples.
Besides the Pacific sardines common on the West Coast, many of the fish appeared to be another species.
“That was the ‘aha moment’ when we realized we were looking at a second species of sardine.”
The analysis shows that of the 345 sardine samples collected during NOAA Fisheries’ 2021 and 2022 Coastal Pelagic Species Surveys, all of the fish in 2021 were Pacific sardines, but those collected in 2022 were a mix of Pacific sardines and Japanese sardines.
Examination of another 825 sardines collected the following year found the same result: many were Japanese sardines. Known only from the west side of the North Pacific Ocean near Asia, the Japanese species had not been documented on the West Coast before.
The scientists from NOAA Fisheries and other institutions reported the surprise appearance today in the journal Molecular Ecology. Both species look so similar that only genetic examination can tell them apart. The scientists took advantage of recent advances in genomic sequencing to examine data from millions of genetic markers and constructed full mitochondrial genomes for sardine to verify the identification.
