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Whale sharks — The beauty of science and technology is that they enable us to learn more about areas in which we were previously interested.
Doctors did not begin using ultrasonography for pregnancy testing until the 1950s and 1970s.
Since then, similar breakthroughs have enabled humans to track the pregnancy of animals, mostly cats and dogs.
Recent research, on the other hand, may have identified a technique to learn more about how whale sharks reproduce.
Initial thoughts
Previously, scientists believed that enlarged patches on the undersides of female whale sharks signified pregnancy.
However, a technique for free-swimming animals was employed for the first time, proving that it was just skin and muscle.
According to researchers in the March 23 edition of Endangered Species Research, the humps, like breasts in humans, may comprise a secondary sex characteristic in mature females.
Scientists are investigating many unique methods to understand more about whale shark reproduction, including underwater “jet packs” and blood tests.
The animal
The International Union for Conservation of Nature has classified whale sharks, or Rhincodon typus, as severely endangered.
Only an estimated 100,000 to 238,000 ocean residents remain, reflecting a more than 50% decrease over the last 75 years.
Whale sharks can reach speeds of up to five kilometers per hour and have an average length of 12 meters.
Scientists are unaware about whale shark reproductive biology due to the creature’s scarcity.
Biologists obtained experience by analyzing the capture of a pregnant female by a commercial fishing boat in 1995.
“Protecting organisms without knowing about their biology is like trying to catch a fly with our eyes closed,” said Okinawa Churashima Foundation fishers biologist Rui Matsumoto.
Okinawa Churashima Foundation performs subtropical animal and plant research in order to improve and maintain natural resources in national parks.
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Research
Matsumoto collaborated with Kiyomi Murakumo, a shark researcher at Okinawa Churaumi Aquarium, to learn more about whale sharks and how to keep up with them.
The researchers used underwater jet packs to swim alongside the whale sharks. (attacked scuba tanks with propellers).
The scientists then placed a 17-kilogram suitcase with a waterproof ultrasonography wand over the undersides of 22 female whale sharks swimming near the Galápagos Islands, drawing blood with needles.
The ultrasound wand had never been used on free-swimming animals outside of an aquarium prior to the research.
According to research collaborator and Marine Megafauna Foundation whale shark biologist Simon Pierce, the two studies were tough.
The Marine Megafauna Foundation is a non-profit committed to marine conservation via research.
According to Pierce, the whale shark possesses some of the thickest skin of any animal, measuring over 30 centimeters thick.
Another worry was the possibility of saltwater contaminating the blood samples.
To overcome the challenge, researchers created a two-syringe system in which the first syringe generates a vacuum while the second syringe pulls blood.
Lab tests
The samples were then taken to the lab, where the scientists determined that the hormone levels in the blood samples from six females were identical to those reported in imprisoned immature females in aquariums.
According to the findings, the wild females were too young to reproduce.
Two of the 22 female sharks were found to have egg follicles on ultrasound, indicating that they were sexually mature but not pregnant.
Tech innovations
Noninvasive methods utilized on whale sharks have allowed researchers to learn more about other fragile marine animals.
According to Simon Pierce, waterproof ultrasonography wands mounted on poles are now used on tiger sharks in areas where the predators are coaxed in with food.
Rachel Graham, a marine conservation scientist and the founder of the MarAlliance, thought that developing the underwater sampling method was groundbreaking.
She is unconvinced that wild sea creatures such as faster-swimming sharks or other marine mammals will agree to such trials.
“What makes whale sharks fairly unique… is that they move relatively slowly at times, have the ability to remain stationary,” Graham pointed out.
“They tolerate the presence of other animals – such as us – nearby.”
Graham has studied sharks all throughout the world.
According to Pierce, the new methods might show researchers where whale sharks give birth by using satellite tracking.
There is little known about whale shark pups, such as whether they are born in shallow or deep water, if they are delivered one at a time, and if mothers cluster to give birth.
“Assuming they do have some sort of breeding or pelagic nursery area we can identify… then that obviously goes quite a long way towards conserving the population,” said Pierce.
