October 28, 2024 — Gary Longo was looking for what he thought would be small genetic differences across a single species of small, ocean-dwelling fish: Pacific sardine.
But as he examined the early data, he suddenly got a sinking feeling. He was looking at what appeared to be two completely different species.
Pacific sardines are small but ecologically important fish. For fishery management purposes, they are usually grouped into three subpopulations: the northern stock, the southern stock and the Gulf of California stock.
Longo, a contractor with the National Oceanic and Atmospheric Administration’s Southwest Fisheries Science Center, was part of a group looking to see if the different sardine stocks were genetically distinct from each other.
Now, as he looked at the data, he thought he must have made a mistake. Maybe he’d accidentally swapped plates with different samples.
Gradually, he and Matt Craig, a research geneticist with the center, realized they were looking at a sardine, but a species of sardine they had never detected along the West Coast of North America before: Japanese sardine, thousands of miles away from home.