Fish follow their noses back to tropical reefs

updated 12:40 p.m. ET Jan. 9, 2007

WASHINGTON - Baby tropical fish, drifting at the mercy of ocean currents, probably follow their noses back to their home reefs when they grow large enough to swim, researchers said Monday.

Fish that dwell on Australia’s Great Barrier Reef generally like to stick close to home, where they know where to find food and hide from predators.

But in their first few weeks of life, lacking the ability to swim, larval fish can drift up to 20 miles (32 kilometers) from where they were born. They likely rely on their sense of smell to make their way back home, according to scientists at the Marine Biological Laboratory in Woods Hole, Mass.

Much as subway riders look for signs to make sure they are on the right train, the fish use smell to find an ocean current, several of the facility’s biologists found.

“Fish have as good a nose as anybody,” said Jelle Atema, a professor at Boston University and Woods Hole who took part in the research. “You think of dogs and rats as super smellers, but eels and catfish and hammerhead sharks are at least as good.”

The cardinal fish, popular in home aquariums, prefers to stay on the reef on which it was born and uses its nose to distinguish one reef from another, he said.

The neon damselfish, another popular aquarium species found throughout the Pacific, is not as picky and can live on several reefs. This fish uses its sense of smell to find its way back to safety when it drifts toward the open ocean, Atema said.

The biologists were not able to prove conclusively that fish navigate by smell, but Atema said their sense of hearing would not help them in distances over half a mile.

The findings will be published this week in the Proceedings of the National Academy of Sciences.

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