University of Illinois-Chicago geneticists led by Associate Professor Jennifer Schmidt studied the DNA of 68 whale sharks from 11 locations across the Indian and Pacific oceans and the Caribbean Sea.
"Our data show whale sharks found in different oceans are genetically quite similar, which means that animals move and interbreed between populations," said Schmidt. "From a conservation standpoint, it means whale sharks in protected waters cannot be assumed to stay in those waters but may move into areas where they may be in danger."
Whale sharks can grow more than 50 feet and weigh more than 20 tons. The whales don't breed until they are about 25-30 years old. The large animals are especially prized by fishermen for meat and fins used in soup.
Schmidt said she hopes efforts such as ecotourism programs, which often include swims with the whales, prove to be an attractive economic alternative to fishing.
"People in many countries have come to realize that whale sharks are more valuable alive than dead," she said.
The research is reported in the online journal PLoS One.