Hammerhead Shark

Tag tracks travels

Rebecca McCarthy

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9/14/2015 — Marine biologists know a great deal about the feeding, breeding and traveling habits of many kinds of sharks, such as the great white. Now they have a chance to discover more about another kind of shark whose habits have remained somewhat mysterious.

For the first time, scientists fitted a satellite-tracking device on a hammerhead shark off the coast of California two months ago. Positioned on the dorsal fin, the device is expected to record information for two or three years. Since it was installed, researchers have learned the shark has traveled more than 1,000 miles, swimming all the way from San Clemente Island to Mexico and back.

”The surprising thing we’ve learned from this is just how much they move around within a season,” said Russ Vetter, Senior Scientist at NOAA Fisheries’ Southwest Fisheries Science Center in La Jolla, Calif. “This one went way down to central Baja and then shot back up here again just to find food, and that is a lot of territory for an animal to cover.”

The animal tagged was a female smooth hammerhead, one of three kinds of hammerheads seen in the waters off California. The others are bonnethead and scalloped hammerheads.

Last year’s El Niño weather pattern raised water temperatures, creating “the warm blob,” patches of warm water along the California coast. The higher temperatures are thought to have attracted the hammerhead, which thrives in warmer waters.

The scientists have learned that the female hammerhead stayed close to the coast except for a side trip of a few hundred miles off the Baja coast, looking for the food that makes up her diet. Vetter says swimming that distance in search of fish and squid suggests the food isn’t abundant and “tells us something about conditions out there.”

The chance to track the tagged shark during a warm El Niño year may offer clues about how hammerhead habitats may be affected by climate change and gradual warming.

“It’s certainly possible they may spend more time farther north,” Vetter said. “We’ll be very curious to watch how far north this shark goes, which could give us an idea what to expect in the future.”

Source: NOAA

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