Whale sharks are indisputably gigantic. At an average height of eight or nine meters (roughly 28 feet), they’re huge compared to some of your favorite marine life. But for nearly a decade, the battle of the sexes has been raging: Who is the eldest, male or female?
According to a new study published in Frontiers in Marine Science on Wednesday, a decade-long analysis confirmed that female sharks are the reigns of the largest fish in the sea – outpacing males to average 14 meters (about 46 feet).
Mark Mikan, an aquatic biologist at the Australian Institute of Marine Sciences and first author on the paper, noted that some whales reached up to 18 meters (59 feet) long.
“This is just so huge – the size of a bus that bends down a city street,” he said. “But even though it is large, it grows very slowly. It is only about 20 cm or 30 cm in size per year.”
Due to the slow growth rate, the team tracked 54 individual whale sharks over 10 years, and recorded more than 1,000 measurements with stereo video cameras.
“It’s basically two cameras that are mounted on a frame that gets pushed in when you’re underwater,” said Brett Taylor, a biologist at the Australian Institute of Marine Sciences and co-author of the study.
“It works the same way our eyes do – so you can calibrate my two videos and get a very accurate shark measurement,” Taylor said.
The team has also discovered that the increased size of a female whale shark may be beneficial when it comes to having offspring. Only one whale shark has been documented, but unlike most sharks carrying between 2 and 12 juveniles, a whale shark carries up to 300.
Discovery may also have implications for conservation efforts. Whale sharks have been listed as an endangered species since 2016. Due to their long growth rates, the targeting of whale sharks by hunters may further reduce the numbers of these animals.
“If you are a very slow growing animal and it takes 30 years or more to reach maturity, chances are the chances of a disaster occurring before you have a chance to reproduce are very high,” said Mican.
“This is a real concern for whale sharks.”
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