Young Fish Return to "Home Reefs" to Settle Down

<< Back to Page 1   Page 2 of 2

Clown anemonefish lay their eggs on bare rocks, which are tended by the parents for several days.

After hatching, the free-swimming larvae typically settle down near sea anemones after just 11 days, making the fishes' stay-at-home tendency not particularly surprising.

(Read "No Nemo: Anemones, Not Parents, Protect Clownfish" [June 5, 2003].)

The untended eggs and larvae of vagabond butterflyfish, on the other hand, may spend four to six weeks drifting with the currents—a trait shared by many commercially important fish species.

Right now little is known about how far the butterflyfish larvae travel and how the juveniles find their way back to their parents' reef, Almany said.

"We can only guess about how they might locate the exact reef on which they were born," he said. "Perhaps some form of imprinting, such as a chemical 'memory' of home."

Not Reseeding Reefs?

Robert Steneck is a marine ecologist at the University of Maine who was not involved in the study.

He noted that previous studies had often assumed high rates of dispersal in coral reef fish, with local populations maintained by young fish arriving from across a broad region.

Similarly, the theory behind many marine reserves is that the offspring of fish in protected areas will help maintain populations far beyond reserve boundaries.

Almany's team, Steneck said, "found the best coral reef system, the best marking tool, and the right species of fish to empirically test the theories. Their results were very surprising but very important indeed."

The finding that fish populations on coral reefs may largely be locally generated means the benefits of reserves may not extend as far as had been hoped.

"The stated goal of many [marine] reserves is that they can be a source of larvae for effectively reseeding damaged reefs downstream," Steneck said.

"We might want to increase our efforts to protect reproducing fish outside of reserves," he continued, "if we don't want to see growing dead zones throughout the world's reefs."

Free Email News Updates
Sign up for our Inside National Geographic newsletter. Every two weeks we'll send you our top stories and pictures (see sample).

<< Back to Page 1   Page 2 of 2


SOURCES AND RELATED WEB SITES

ADVERTISEMENT

NATIONAL GEOGRAPHIC'S PHOTO OF THE DAY

NEWS FEEDS     After installing a news reader, click on this icon to download National Geographic News's XML/RSS feed.   After installing a news reader, click on this icon to download National Geographic News's XML/RSS feed.

Get our news delivered directly to your desktop—free.
How to Use XML or RSS

National Geographic Daily News To-Go

Listen to your favorite National Geographic news daily, anytime, anywhere from your mobile phone. No wires or syncing. Download Stitcher free today.
Click here to get 12 months of National Geographic Magazine for $15.