Adult clownfish spend the majority of their lives within the protection of a sea anemone, but babies swim up to 250 miles through open water in a journey that could be compared to the hit Pixar film "Finding Nemo."
In the animated film, the character Nemo sets out on a trying journey to find his way home after being captured by humans and thrown in a fish tank; real-life clownfish larvae make an epic migration also in hopes of finding a protective anemone to start a life in. The practice could help this species better-adapt to environmental change, the ARC Centre of Excellence in Coral Reef Studies reported. The migration is the furthest distance a coral reef fish has been documented to travel.
"In the past we haven't known where they go, but now we've been given a rare glimpse into how far they can swim, crossing large tracts of ocean to find new homes," said study co-author Hugo Harrison from the ARC Centre of Excellence for Coral Reef Studies (Coral CoE) at James Cook University. "Knowing how far larvae disperse helps us understand how fish populations can adapt to environmental changes. The further they can swim, the better they can cope."
To make their findings a team of international researchers collected samples of the two known types of clownfish in southern Oman, Omani clownfish and Amphiprion omanensis. There are only two coral reef systems along this coast, separated by a stretch of water spanning about 25 miles. The team collected tissue samples from about 400 clownfish as a sort of "fingerprint" to determine how far the larvae had traveled.
"Like the accents that we have that allow us to tell an Englishman from an American, fish populations can develop their own genetic signatures," Harrison said. "We can look at the signature of each fish and tell whether it belongs there or not. It's like finding an Englishman in New York, they stand out."
The team found the fish were regularly taking the long journey between these two reefs in only a few days, possibly using ocean currents to propel themselves along. The team observed that most of the fish traveled north to south, which corresponds with monsoon-driven currents in the region. Fish in both populations made second-generation migrations, but most settled in sea anemones long enough to reproduce.
"The findings change our understanding of marine populations. They're not small and separate as we often assume, rather this research shows they're often vast and inter-connected," said study leader Stephen Simpson from the University of Exeter.
The findings were published in a recent edition of the journal PLOS ONE.
