Sightings of large fish are increasing. Climate change could be the cause.

Sightings of big fish seem to have increased around the world: in the past year and a half, there have been reports of a record 661 pound ray in Cambodia, a 240 pound lake sturgeon outside of Detroit and a 100 -pound fish opah on the Oregon coast. As these fish appear in unexpected places, experts say climate change could be helping to fuel this trend.

The fish “don’t get bigger, they move to new environments,” said Francisco Werner, director of science programs at the National Oceanic and Atmospheric Fisheries Administration.

As the waters warm – powered by the oceans absorbing more than 90% of the excess heat from global warming – the fish are on the move. Werner’s work has shown that there is a dominant trend in these changes, with fish populations moving towards the poles and colder waters.

They “try to maintain optimal 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 northern Oregon coast. And Tiffany Boothe, assistant manager of an aquarium in the small seaside community of Seaside, said this isn’t the first time southern warm-water fish have appeared in Oregon.

Salmon travel deep in the Pacific. As it warms up, many “don’t come back.”

On the other coast, drastic temperature changes in the waters have resulted in altered conditions for fish. In the Gulf of Maine, for example, the waters have warmed five times faster than the global average over the past 15 years, said Kathy Mills, a researcher at the Gulf of Maine Research Institute. As a result, Maine’s waters may offer insight into future fish movements as global warming continues. Mills said the cod fishery “really supported the nation’s early fisheries, and we’ve seen those populations decline as the waters warm.”

“They just aren’t able to be as productive and continue to produce as many young and make them as viable and survive to adulthood as they could in cooler temperature conditions” , Mills said.

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In contrast to the decline in cod, Mills notes that “American lobster is now experiencing temperatures that are truly conducive to high population productivity.”.”

As a result, the lobster stimulated Maine’s economy as the nation’s largest single-species fishery. But if warming trends continue, they could change.

Even as Maine experiences a lobster boom, Mills worries about the future of the species with uncontrolled global warming.

“The question now is whether we see temperatures reaching or exceeding thresholds where they are no longer conducive to this high productivity of American lobster,” she said. It “raises questions about what the future of fishing might look like”.