Researchers Calculated a Whale Shark’s Age Based on Cold War-Era Bomb Tests
by Theresa Machemer/Smithsonianmag.com
Whale sharks are the world’s largest fish, recognizable by their white-speckled and striped backs. But as whale sharks age, they also gain stripes on their vertebrae.
The layers, called growth bands, build up like the rings in a tree trunk, so the older a whale shark is, the more bands they have. Now, by using the radioactive chemical signature left behind by Cold War-era nuclear bomb tests, researchers have definitively decoded the big fishes’ bands to figure out how long they live.
The research, published on Monday in Frontiers in Marine Science, settles an ongoing debate over how long it takes each growth band to form; experts previously suggested either 6 or 12 months per band. But getting it right has implications for whale shark conservation strategies. The new evidence points to the longer end of the previous estimates: each band takes about one year to form. And, knowing that, the researchers found that the giant sharks can live to at least 50 years old.
“Basically what we showed is we have a time stamp within the vertebrae,” Mark Meekan, a biologist at the Australian Institute of Marine Science, tells Liz Langley at National Geographic. “We count the bands from there, and ….read more: