In an ambitious research project, geneticists from the University of Illinois took DNA samples from 68 whale sharks from around the world - and found that the giant fish shared very similar genetic codes.
The findings have two implications for the sharks: first, that their numbers are dwindling, causing offspring to lose genetic diversity, and second, that whale sharks must be protected worldwide in order to recover to a healthy population level since they interbreed across the globe.
These gentle giants, which grow up to 50 feet in length and feed on plankton, are especially vulnerable to overfishing because they reproduce only after turning 25 or more years old, and then breed infrequently. Unfortunately, whale sharks are sometimes killed for shark fin soup.
The IUCN Red List categorizes whale sharks as "threatened," but the truth is that not much is known about the species' population size. This new study is a critical step in understanding a little-known fish.