Study says Nemo can really find way home

The cute clownfish made famous by the hit cartoon feature Finding Nemo really can find his way home after spending months at sea, researchers have found.

An Australian-led team of coral reef scientists has discovered that 60 per cent of clownfish complete the journey back to their reef of origin after being swept into the open ocean as babies.

The team of Australian, American and French scientists say they have achieved a world breakthrough that could revolutionise the sustainable management of coral reefs and help restore threatened fisheries.

The team, led by Dr Geoff Jones and Dr Glenn Almany of the Australian Research Council Centre of Excellence for Coral Reef Studies at Queensland's James Cook University, pioneered a new way to study fish populations by "tagging" adult fish with a minute trace of a harmless isotope which they pass on to their offspring.

The findings were published in the international journal Science.

Working on coral reefs in a protected marine area in Papua New Guinea, the researchers tagged more than 300 female clownfish and vagabond butterflyfish with a barium isotope.

The researchers found that 60 per cent of their offspring returned to the tiny home reef - only 300 metres across - after being carried out to the sea as babies.

"Just as importantly, 40 per cent of the juveniles came from other reefs that are at least 10 kilometres away, which indicates significant exchange between populations separated by open sea," Dr Almany said.

"This shows how marine protected areas can contribute to maintaining fish populations outside no-fishing zones.

"...If we can understand how fish larvae disperse, it will enable better design of marine protected areas and this will help in the rebuilding of threatened fish populations."

The team is conducting further research at an aquaculture facility in Bali, looking at the possibility of applying the tag to coral trout.

They hope to conduct trials on coral trout off Great Keppel Island on the Great Barrier Reef and in PNG, as well as work with a threatened species, the Nassau groper, in the Caribbean.