Climate Change Draws Great White Sharks North, Threatening Ecosystem

Santa Cruz, (UrduPoint / Pakistan Point News - 4th Oct, 2023) There never used to be young great white sharks basking off the busy beaches of central California, but as climate change starts to bite, warmer waters are enticing them north -- with possibly catastrophic consequences for a whole ecosystem.

Despite their fearsome reputation, brought about in part by the "Jaws" movie franchise, the main risk from these predators is not to swimmers and surfers -- or even the local police chief -- but to otters.

"What we've been finding is that over time the number of bites on sea otters has increased in this region drastically," says marine ecologist Salvador Jorgensen of California State University Monterey Bay.

"That's having a real impact on the sea otter population."

And -- in an illustation of how interconnected ecosystems are -- that could have far-reaching consequences for all kinds of species in this wildlife-rich area.

Great white sharks are some of the most majestic, most studied, and most feared of ocean dwellers.

Growing to around 16 feet (4.9 meters), they roam the world's seas thousands of feet deep to satisfy a voracious appetite for seals, sea lions and dolphins.

They live for upwards of 70 years and give birth to litters of live pups, who are left to fend for themselves from an early age.

But because white sharks are endotherms -- warm-bodied, like mammals -- youngsters are vulnerable to the cold of the ocean depths, and spend their time in warmer pockets of water in coastal regions.

Until a decade or so ago, that meant juveniles would only be found as far north as southern California.

But, says Jorgensen, that's changing.

"We documented the sudden occurrence of much smaller sharks than had ever been seen here before," he told AFP in Monterey Bay, hundreds of miles (kilometers) north, where he attaches acoustic transmitters to individuals that allow him to track their travels.

"As ocean temperatures have been warming through a series of El Ninos, and heat waves, many species have been shifting their range further north further towards what were historically cooler areas."

That's what brings them into contact with sea otters, who hang around in the rich kelp forests offshore.