International Whale Shark Day

Anglers are known to exaggerate the size of the fish they catch, but today we’re covering a fish whose size doesn’t need any help.  The whale shark is the world’s biggest fish, and August 30 is its own day.  Happy Whale Shark Day!

Whale Shark (photo by Elias Levy)

So, first off, let’s be clear—this animal is not a whale, but it is a shark.  That makes it a fish, not a mammal, and it is clearly the world’s biggest fish (in second place is the basking shark, barely half the size of the whale shark).  Mature whale sharks are the size of a school bus, as long as 50 feet and as heavy as 40 tons.  Big monsters, eh?

But, no, they aren’t monsters.  Whale sharks are gentle creatures—big to be sure, but docile to the extreme.  They live in tropic seas around the globe and generally inhabit shallow water and swim near the surface, frequently encountering humans.  A tourist industry has grown around seeing and swimming with whale sharks, which often enjoy a little scratch behind the, uh, gill slits.

Whale sharks are ancient creatures, based on the fossil record, but have been known as living specimens for only two centuries.  Females give birth to live young, dozens at a time.  Various descriptions state that the animals “migrate,” but it seems to me that a better description is that they swim continuously, often covering long distances.  Their lifespan mimics their physical size—up to 70 years. They filter small animals out of the water column, just like the baleen whales (and hence their name), eating as much as 50 pounds per day.  But unlike filter-feeding whales, whale sharks also can pump water actively through their gills, causing a suctioning effect to capture small fish and other organisms.

Whale shark showing pattern of light dots and shapes (photo by Nicholas Lindell Reynolds)

Individual whale sharks are covered with light colored markings, mostly round,  in patterns that remain constant over time and allow individuals to be identified.  A catalogue of more than 7,000 individuals has been created, but overall population size is much larger, perhaps 100,000 or more, according to IUCN. 

However, IUCN also estimates that whale sharks have decreased in abundance from pre-exploitation levels.  Populations in the Indo-Pacific are down about two-thirds, and in the Atlantic about one-quarter.  Because the species likes shallow water and does not avoid humans, overfishing and vessel strikes have caused the population decline.  Therefore the species is judged as “endangered” by IUCN and classified as an Appendix II protected species by CITES.

I’ve looked extensively to find the origin of International Whale Shark Day, but with no luck.  The day, it seems, is much like the animal it honors—silent and mysterious.  Tired of the cliched expression “the elephant in the room”?  I recommend trying “the whale shark in the aquarium!” 

Whale sharks and human swimmers are compatible (photo by Feefional123)

References:

Australian Department of Agriculture, Water and the Environment.  Whale Shark (Rhincodon typus).  Available at:  https://www.environment.gov.au/marine/marine-species/sharks/whale-shark.

Pierce, S. J. and B. Norman.  2016.  Rhincodon typus.  The IUCN Red List of Threathened Species.  Available at:  https://www.iucnredlist.org/species/19488/2365291#text-fields.

World Wildlife Fund.  Whale Shark.  Available at:  https://www.worldwildlife.org/species/whale-shark.  

This Month in Conservation

August 1
Hawaii National Park Created (1916)
August 2
White Giraffes Found in Kenya (2017)
August 3
Arbor Day in Niger
August 4
Liang Congjie, Pioneering Chinese Environmentalist, born (1932)
August 5
First Traffic Light Installed in U.S. (1914)
August 6
Rajendra Singh, the Waterman of India, Born (1959)
August 7
World’s Oldest Tree Cut Down, Accidentally (1964)
August 7
Elinor Ostrom, Noble Laureate in Economics, Born (1933)
August 8
Banqiao Dam Collapse, World’s Biggest Dam Disaster (1975)
August 9
Smokey Bear Born (1944)
August 10
John Kirk Townsend, Pioneering Naturalist, Born (1809)
August 11
Gifford Pinchot, Father of American Forestry, Born (1865)
August 12
“The Lorax” Published (1971)
August 13
Roald Amundsen Completes Northwest Passage (1905-1906)
August 14
Hetch Hetchy Began Producing Power (1925)
August 15
Sponge Act passed (1914)
August 16
E. F. Schumacher, Environmental Economist, born (1911)
August 17
Cape Hatteras National Seashore created (1937)
August 18
Margaret Murie born (1902)
August 19
Cickamauga and Chattanooga Battlefield established
August 20
The Great Fire (1910)
August 20
Rajendra Pachauri, Nobel Peace Laureate in Climate Change Research, Born (1940)
August 21
“Bambi” Released (1942)
August 22
Loch Ness Monster first seen (565)
August 23
Chile’s Atacama Desert Blooms (2017)
August 24
Katahdin Woods and Waters National Monument, Maine, Established (2016)
August 25
National Park Service Born (1916)
August 26
Krakatau Volcano Erupted (1883)
August 27
First Oil Well Drilled (1859)
August 28
Roger Tory Peterson, Ornithologist, Born (1908)
August 29
Henry Bergh, Founder of ASPCA, Born (1813)
August 30
International Whale Shark Day
August 30
Lord Walsingham Shot 1,070 Grouse (1888)
August 31
John Muir Home preserved (1964)
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