Female whale sharks are officially the biggest fish in the sea
It is pretty much undisputed that whale sharks are gigantic. With an average adult length of eight or nine meters, they are whoppers compared to some of your favorite marine life. But for almost a decade the battle of the sexes remained: who is taller, male or female?
According to a new study published in Frontiers in Marine Science on Wednesday, decades of analysis has confirmed that female sharks are at the top as the largest fish in the ocean, overtaking males by averaging 14 meters.
Mark Meekan, fish biologist at the Australian Institute of Marine Science and first author of the paper, found that some whales have reached a length of up to 18 meters.
“It’s absolutely huge – about the size of a flexible bus on a city street,” he said. “But even though they’re big, they grow very, very slowly. It’s only about 8 or 12 inches a year.”
Due to the slow rate of growth, the team tracked 54 individual whale sharks over a period of 10 years and recorded more than 1,000 measurements with stereo video cameras.
“It’s basically two cameras set up on a frame that you slide underwater with you,” said Brett Taylor, biologist at the Australian Institute of Marine Science and co-author of the study.
“It works just like our eyes – so you can calibrate the two video recordings and get a very accurate measurement of the shark,” said Taylor.
The team also discovered that enlarging female whale sharks can be beneficial for producing offspring. Only one pregnant whale shark has ever been documented, but unlike most sharks who carry between two and twelve cubs, the whale shark held up to 300.
The discovery can also have an impact on conservation efforts. Whale sharks have been classified as critically endangered since 2016. Because of their long growth rates, whales targeted by fishermen could lead to a further decline in the animal population.
“If you’re a very slow growing animal and it takes 30 years or more to reach maturity, the odds of disaster happening before you have a chance to reproduce are probably pretty high,” Meekan said.
“And that’s a real concern for whale sharks.”