Whale Sharks or locally known as “Tuki” or “Butanding” had been present in our coastal waters around Oslob, Cebu for the last 10 years or so. The gentle giants were first sighted in Sorsogon, earning it the title of the Whale Shark Capital of the Philippines.
The whale shark (Rhincodon typus) is an amazing animal, the biggest fish in the sea, yet scientists still know very little about its life and habits. Whale sharks have a flattened head, a large mouth, and a dark blue or brown body covered in white spots and stripes. Scientists believe this body marking acts as camouflage to protect these animals (particularly juveniles) from predators.
These fish have skeletons made entirely of cartilage in comparison to other fishes that have skeletons made of bone. The skin of a whale shark has small tooth-like scales called dermal denticles that serve as protection and improve swimming by reducing drag.
Here are some amazing Fast Facts about these gentle giants of the underwater world:
- They are sharks, not whales. They commonly earn the name ‘whale sharks’ due to their size and feeding behavior. All sharks are fish, unlike whales, which are mammals.
- They don’t swallow you. Although their mouths are big, still their throats are not wide enough to let big objects pass through.
- They don’t bite you. They may have over 3000 teeth but they look like velcro and are too small to cause any damages.
- The deepest recorded whale shark dive is 1,300 m (>4,000 ft), while the deepest dive ever recorded by a whale shark is 1,720 m (over 5,000 ft).
- Whale sharks are found in tropical and temperate waters around the world, in shallow coastal waters and the open ocean.
- They might be solitary animals but they are known to feed in large groups.
- Aside from them, two other species that filter feed are Megamouth Sharks (Megachasma pelagios) and Basking Sharks (Cetorhinus maximus).
- Pups is the term used for newborn whale sharks. They are born 18-20 inches long.
- They are Ovoviviparous, meaning young hatch from eggs inside their mother and then birthed alive.
- Their gills can filter particles as small as .04 inches [1mm], just about the width of the tip or a pencil.
Other significant tidbits about the whale sharks are as follows:
- Similar to the fingerprint of a human, the pattern of spots around the gill area are unique to each individual allowing researchers to identify individual sharks.
- They feed on a variety of plankton and nekton, such as copepods, crab larvae, fish eggs, thimble jellyfish, a variety of krill, and small deep-sea fishes.
- The feeding technique of whale sharks is similar to a vacuum cleaner — filtering by sucking and gulping — but may vary depending on the amount of food in the water. They feed by swimming forward with their mouths slightly or fully open to strain food from water passing through their gills, by gulping water on the surface while swimming, or by gulping water while vertically suspended in water.
- The only known predator of the whale shark is humans.
- Worldwide, whale sharks occur in waters of over 100 countries and have a broad distribution usually between latitudes 30°N and 35°S in tropical and warm temperate seas, both in oceanic and coastal waters. They congregate in feeding areas, often undertaking long migrations to reach areas rich in food sources.
The quiet seaside town of Oslob gained international publicity after the local government began sanctioning the feeding of whale sharks in the fishing Barangay of Tan-Awan in 2012.
What began as a small tourist operation has skyrocketed into a booming industry that continues to grow, mostly unregulated, each year. While the activities in Oslob have resulted in a large boost to the local economy, they raise ongoing conservation and sustainability concerns.
Threats and Vulnerabilities
Biggest Threat: Fisheries. Target fisheries cater to demands for whale shark products, such as fins for trophy displays, and liver oil for cosmetic and medicinal products.
Whale sharks are also frequently caught as by-catch. By-catch reports mostly come from purse-seine fisheries that use whale sharks as an indicator of skipjack tuna presence. Once fisherman spot whale sharks, they assume tuna is nearby and set nets in a perimeter around them. The sharks become entangled in the nets and perish.
The surface-swimming behavior of whale sharks also makes them vulnerable to injuries from boat strikes. Many sharks exhibit propeller cuts, lacerations, and other scars from boats.
Thinking about going Whale Shark watching in Oslob? Or do you know someone who has the interest in getting to more of these gentle giants? Let us know! See you there!