Big fish sightings appear to have spiked around the world: In the last year-and-a-half, there have been reports of a 661-pound, record-breaking stingray in Cambodia, a 240-pound lake sturgeon outside Detroit and a 100-pound opah fish on the Oregon coast. As these fish show up in unexpected places, experts say climate change may be helping drive this trend.
The fish “aren’t growing larger, they are relocating to new environments,” said Francisco Werner, director of scientific programs at National Oceanic and Atmospheric Administration Fisheries.
As waters warm — fueled by oceans absorbing more than 90 percent of the excess heat from global warming — fish are relocating. Werner’s work has shown that there is a prevailing pattern to these shifts, that fish populations are shifting toward the poles and cooler waters.
They are “trying to maintain some optimum temperatures and preferred temperature ranges that they like,” he said.
Last year, a huge opah fish — the kind typically found in tropical waters — washed up on the north Oregon coast. And Tiffany Boothe, assistant manager at an aquarium in the small beach community of Seaside, said it wasn’t the first time southern, warm-water fish had shown up in Oregon.
On the other coast, drastic temperature shifts in waters have meant changing conditions for fish there. In the Gulf of Maine, for example, waters have warmed five times faster than the global average for the past 15 years, said Kathy Mills, a researcher at the Gulf of Maine Research Institute. As a result, Maine’s waters may offer a glimpse into future fish movement as planetary warming continues. Mills said the cod fishery “really supported the first fisheries in the country, and we have seen these populations decline as waters warm.”
“They just aren’t able to be as productive and continue producing as many young and have those be as viable and survive to adulthood as they could under cooler temperature conditions,” Mills said.
In contrast to the dwindling cod, Mills notes that “American lobster now is experiencing temperatures that are really conducive for high population productivity.”
As a result, lobster has boosted Maine’s economy as the highest value single species fishery in the country. But if warming trends continue, they may move on.
Even as Maine experiences a lobster boom, Mills worries about the species’ future with unchecked global warming.
“The question now is whether we’re seeing temperatures move into or beyond thresholds where they’re no longer conducive to this high productivity of American lobster,” she said. It “raises questions about what the future of the fishery might look like.”