The ancestry of the whale shark goes back to the Jurassic and Cretaceous periods 245-65 million years ago, when the present groups of sharks began to appear. Yet Prior to the mid-1980's, there had been less than 350 confirmed reports of whale sharks worldwide.
Credit: Fred Anderson
Whale Shark
Source: |
| 06-21-2009
A new study has discovered that whale sharks around the world are all related
hey are known to inhabit both deep and shallow coastal waters and the lagoons of coral atolls and reefs.hale sharks Rhincodon typus have a broad distribution in tropical and warm temperate seas, usually between latitudes 30°N and 35°S, which form a band around the equator. Very little is known about their biology or ecology and they have only been studied in any depth in the last 10-15 years.
ustralia is one of the most reliable locations to find whale sharks. Regular sightings have also been recorded from many other regions including India, the Maldives, South Africa, Belize, Mexico, the Galapagos Islands, Southeast Asia and Indonesia.
orth $20,000 each
Unfortunately, the meat of whale sharks is considered to be a delicacy by many people in China, Taiwan, Singapore, Korea and Japan. Here, whale shark meat is one of the most expensive fish that can be bought with each shark being worth an estimated $20,000.
hese active fisheries mean that whale sharks are severely over-exploited in this part of their range.
o assess wether local overfishing could affect worldwide populations, a team led by scientists at the University of Illinois in Chicago took DNA samples from 68 whale sharks from the Indian and Pacific Ocean and the Caribbean Sea. DNA microsatellites were compared between the sharks and found to be remarkably similar throughout the whale sharks’ range.
his means that these sharks migrate between populations and interbreed, and that any fisheries focused on these sharks can have a global impact.
ll related
Lead scientist Jennifer Schmidt said: “Our data show that whale sharks found in different oceans are genetically quite similar, which means that animals move and interbreed between populations.
rom 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."
source : X Ray magazine
