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Warm-blooded fish faster than cold-blooded peers, equally vulnerable to climate change

Warm-bloodedness helps white sharks swim faster and may help with predation and migration, but may also leave them as susceptible to warming ocean temperatures as other fish. File Photo by Joe Marino/UPI
Warm-bloodedness helps white sharks swim faster and may help with predation and migration, but may also leave them as susceptible to warming ocean temperatures as other fish. File Photo by Joe Marino/UPI | License Photo

July 1 (UPI) -- Most fish are cold-blooded, but some warm-blooded fish have evolved the ability to regulate their own body temperatures.

For decades, scientists have debated the evolutionary advantages gained by internalizing temperature regulation. Now, new research has confirmed that warm-blooded species swim faster, but don't populate waters with a wider range of temperatures.

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In addition to confirming the evolutionary advantages gained by internal temperature regulation, the new research -- published Thursday in the journal Functional Ecology -- suggests warm-blooded fish species, including white sharks and bluefin tuna, are just as vulnerable to climate change as their cold-blooded relatives.

"Scientists have long known that not all fish are cold-blooded," study first author Lucy Harding said in a press release.

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"Some have evolved the ability to warm parts of their bodies so that they can stay warmer than the water around them, but it has remained unclear what advantages this ability provided," said Harding, a doctoral candidate in Trinity College Dublin's School of Natural Sciences.

Some scientists have argued warm-bloodedness allows fish to swim faster, as warmer muscles tend to be more powerful muscles.

Other researchers have suggested warm-bloodedness allows fish to occupy a broader range of temperatures, making them more resilient to climate change.

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For the new study, Harding and her research partners collected real world data from dozens of tagged sharks and bony fish. The research team supplemented their field observations with information from existing databases.

The data captured using bio-logging devices showed warm-blooded fish species swam at average speeds some 1.6 times faster than their cold-blooded relatives. However, the data showed the same species did not occupy a wider range of temperatures.

"The faster swimming speeds of the warm-blooded fishes likely gives them competitive advantages when it comes to things like predation and migration," study co-author Nick Payne said in a press release.

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"With predation in mind, the hunting abilities of the white shark and bluefin tuna help paint a picture of why this ability might offer a competitive advantage," said Payne, assistant professor in zoology in Trinity's School of Natural Sciences.

According to Payne, because warm-blooded fish species aren't able to adapt to wider temperature ranges, as has been previously suggested, they are likely just as sensitive to ocean warming as all the other fish in the sea.

"Findings like these -- while interesting on their own -- are very important as they can aid future conservation efforts for these threatened animals," Payne said.

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