A dead 26' whale shark washed ashore on the west end of Sanibel.

A dead 26' whale shark washed ashore on the west end of Sanibel.

Last week, one of our most majestic sea creatures, a 26’ whale shark, washed ashore dead on Sanibel Island. Whale sharks are the largest species of fish on the planet, and they are filter feeders, meaning they strain plankton from the ocean – the proverbial gentle giant.

 FWC officials visited the scene to conduct a necropsy. 

FWC officials visited the scene to conduct a necropsy. 

Officials from the Florida Fish and Wildlife Conservation Commission (FWC) responded at the scene and conducted a necropsy, which is an autopsy on an animal. The initial findings did not indicate any obvious cause of mortality. Samples of its liver have been sent to labs to better understand if any toxicological causes of death seem apparent.

 The shark's stomach contents were examined. 

The shark's stomach contents were examined. 

 The liver was removed for additional testing. 

The liver was removed for additional testing. 

 The necropsy took many hours to complete. 

The necropsy took many hours to complete. 

Animals in the ocean, like those on land, can die from any number of natural causes. This might just be one of those cases. He was old, or sick, and he died and washed ashore.

If and when we receive additional information from FWC, we will update this post to share any new findings with you.  

UPDATE: The whale shark's death may have been linked to red tide

In the meantime, here are a few things to know about whale sharks:

  • Whale sharks are sharks (not whales), and they are the largest fish in the sea. They can grow to 40 feet in length and 40,000 lbs. in weight. That is the weight of approximately 10 Volkswagen Beetles.
  • Whale sharks feed mainly on plankton, but they may also consume krill, larvae, eggs, squid, and small fish. Juvenile whale sharks eat more than 45 lbs. of food each day.
  • Whale sharks are harmless to humans.
  • Whale sharks are oviviparous, meaning they produce eggs that hatch inside the mother’s body, then give birth to live pups. One pregnant whale shark was found to be pregnant with 300 pups at once.
  • Each whale shark has a unique spot pattern – their spots serve as camouflage, reflecting light in a way that makes it difficult for predators to discern their body shape. Scientists are applying star-mapping astronomy tools to identify individuals by their spot patterns. 
  • Young whale sharks have been found in the stomachs of blue marlin and blue sharks. There are also reports of orcas and other shark species preying on small whale sharks.
  • Humans are the whale shark’s greatest threat. Thousands are harvested each year, mainly for their fins. Serving shark fin soup made with whale shark fins at weddings and banquets is considered especially honorable in Chinese culture. 

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