'Nemo' Finds His Own Way Home

May 4, 2007 — He may have had difficulty finding his way home in "Finding Nemo," but the white and orange clownfish generally finds its way back to its parents after being swept out to sea, new research has found.

A team of Australian, American and French scientists studying pristine coral reefs in Papua New Guinea found that 60 percent of clownfish journeyed back to their tiny home reef after being swept out to the ocean as babies.

Researcher Glenn Almany said it was not known how far the baby clownfish travelled before they trekked home, but that they generally spent 11 days away from their reef before returning.

"Sixty percent of the juveniles that we found were actually produced by the parents on that reef," he said of the study of some 300 female clownfish and vagabond butterflyfish.

"Forty percent of those juveniles had come from somewhere else — and that somewhere else is at least six miles away.

"What that suggests is that populations are connected to each other."

Almany, of Australia's James Cook University, said the tagging technique behind the discovery could revolutionise the management of coral reefs and help restore threatened fish stocks.

The scientists injected female fish with a trace of a harmless isotope which finds its way into their eggs, and can later be observed in the baby fish.

The team's findings, published in the latest edition of the international journal Science, could help improve the understanding of how fish larvae disperse and therefore enable better design of marine protected areas, he said.

The team is currently working on the Indonesian island of Bali to develop a tag for coral trout, a species overfished in some waters.

"Tagging would help you to select the right reefs to protect, in order to maintain the overall population — and the fish catch into the future," Almany said.