SEP 21, 2020 9:13 AM PDT

Female Whale Sharks Crowned Ocean's Largest Fish

WRITTEN BY: Carmen Leitch

After a decade of study, scientists have reached the conclusion that female whale sharks are the largest fish in the oceans. Male whale sharks grow rapidly, and reach an average length of about eight or nine meters in adulthood. Females grow more slowly than males, but overtake the males and reach an average adult length of around fourteen meters. Some even grow to eighteen meters long, noted Australian Institute of Marine Science fish biologist Dr Mark Meekan, who led the research, which has been reported in Frontiers in Marine Science.

"That's absolutely huge: about the size of a bendy bus on a city street," said Meekan. "But even though they're big, they're growing very, very slowly. It's only about 20 centimeters or 30 centimeters a year."

For this study, the researchers conducted fieldwork at Western Australia's Ningaloo Reef over eleven seasons from 2009 to 2019. Whale sharks each have a unique set of spots, so the scientists were able to identify and track 54 individual whale sharks while they grew.

The team took over 1000 measurements of what sharks with stereo-video cameras, noted AIMS marine scientist Dr. Brett Taylor. "It's basically two cameras set up on a frame that you push along when you're underwater," he explained. "It works the same way our eyes do so you can calibrate the two video recordings and get a very accurate measurement of the shark."

Along with the research on wild whale sharks, the researchers also used data obtained from whale sharks in captivity. This research is the first to show that male and female whale sharks grow in different ways, said Meekan.

Image credit: Pixabay

"Only one pregnant whale shark had ever been found, and she had 300 young inside her," Meekan said. "That's a remarkable number, most sharks would only have somewhere between two and a dozen. So these giant females are probably getting big because of the need to carry a whole lot of pups."

In 2016, whale sharks were listed as endangered. Collisions with ships and fishing pose serious threats to these fish.

"If you're a very slow-growing animal and it takes you 30 years or more to get to maturity, the chances of disaster striking before you get a chance to breed is probably quite high," he said. "And that's a real worry for whale sharks."

"This paper has really re-written what we know about whale shark growth," added Taylor.

Sources: AAAS/Eurekalert! via Frontiers, Frontiers in Marine Science

About the Author
  • Experienced research scientist and technical expert with authorships on 28 peer-reviewed publications, traveler to over 60 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
JUL 07, 2020
Cell & Molecular Biology
Anticancer Compound Found in Marine Bacteria
JUL 07, 2020
Anticancer Compound Found in Marine Bacteria
Bacteria live in symbiosis with many animals in the world. These tiny single-celled creatures often play crucial roles i ...
JUL 27, 2020
Plants & Animals
Why Mosquitoes Have a Preference for Human Blood
JUL 27, 2020
Why Mosquitoes Have a Preference for Human Blood
There is a huge variety of mosquitoes in the world - around 3,500 species - and only a few seek humans for their blood m ...
JUL 30, 2020
Drug Discovery & Development
Cats Successfully Treated with Gene Therapy
JUL 30, 2020
Cats Successfully Treated with Gene Therapy
While gene therapy is a promising treatment for multiple diseases caused by a genetic mutation, getting gene therapy age ...
AUG 05, 2020
Microbiology
Revealing the Secrets of a Symbiotic Relationship
AUG 05, 2020
Revealing the Secrets of a Symbiotic Relationship
Some salamanders (Ambystoma maculatum) have a strange relationship with a type of alga (Oophila amblystomatis): they are ...
AUG 28, 2020
Plants & Animals
Will Traps Solve the Invasive Lionfish Problem?
AUG 28, 2020
Will Traps Solve the Invasive Lionfish Problem?
Extravagant and spiny lionfish were once highly sought after by home aquarium hobbyists. These venomous fish are native ...
OCT 11, 2020
Plants & Animals
Fungal Disease Affecting Snakes Is More Widespread Than Thought
OCT 11, 2020
Fungal Disease Affecting Snakes Is More Widespread Than Thought
A team of researchers and personnel on military bases have reported in a project in which they looked for an emerging fu ...
Loading Comments...