Scientists use DNA to study migration of threatened whale sharks

April 8th, 2009 - 3:42 pm ICT by ANI  

Washington, April 8 (ANI): In a new study, scientists have analyzed the DNA of 68 whale sharks from 11 locations across the Indian and Pacific Oceans and the Caribbean Sea, in an effort to study the migration of the threatened species.

The study was conducted by Jennifer Schmidt, University of Illinois at Chicago associate professor of biological sciences, and her colleagues.

The results showed little genetic variation between the populations, which indicates migration and interbreeding among far-flung populations of the big fish.

“Our data show that 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 that whale sharks in protected waters cannot be assumed to stay in those waters, but may move into areas where they may be in danger,” she added.

A tropical fish that can grow 50 feet or longer and weigh over 20 tons, a whale shark’s range can span oceans.

They do not breed until they are about 25 to 30 years old, so it will take a long time for the species to recover from recent population declines.

Whale sharks are listed as threatened, but not every country protects them. The large animals are especially prized by fishermen for meat and fins used in soup.

Little is known about the shark’s biology, perhaps because they have been studied primarily near shore, while mature animals may breed and give birth out in the open ocean.

Nor is much known about neonatal or juvenile sharks, including where they grow to maturity, or how and when they move between regions.

That has made devising effective conservation efforts a problem.

“The only real threat to whale sharks is us,” said Schmidt. “To design proper conservation plans, we need to understand the sharks’ lifestyle. We can only protect their habitat if we know what habitat they use,” she added. (ANI)

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