Wildlife

THE COMPLETE GUIDE TO WHALE SHARKS

By: July 27, 2017 No Comments
 

Gentle Giants

The Indonesian archipelago is home to many remarkable creatures, but few match the majesty and mystery of the world’s largest fish – the amazing whale shark, a gentle giant of the sea.

Evolving during the Cretaceous Era between 146 and 60 million years ago and reaching lengths of up to 20 meters (65 feet), whale sharks are also some of the longest-living creatures on the planet – researchers believe they can live up to 100 years, and even longer in some cases.

They are the ocean’s wanderers, often migrating thousands of miles in short spaces of time. Though largely solitary creatures, clusters of whale sharks are attracted to different areas of the world in intriguing configurations of age and gender.

Indonesia is home to the world’s only known groups of non-migratory whale sharks. In this area of outstanding natural beauty, local fishermen call them gurano bintang, or star sharks – a reference to the characteristic white spot markings that resemble stars formations. Each ‘star’ pattern is unique, making it easy for researchers to track them.

 

A ‘Whale’ of a Fish

With a name like whale shark, it’s easy to be confused about which species these huge creatures belong to. They are indeed members of the shark family, belonging to a group called Chondrichthyes, meaning they are cartilaginous fish without calcified bones. Chondrichthyes include sharks and rays, that are all cartilage except for their teeth and in some cases vertebrae.

Whale sharks earned their name due to their massive size: weighing in at up to a whopping 12,500 kilograms (27,500 pounds), they can grow bigger than a bus, making them appear more whale-like in stature. As cold-blooded fish, they don’t need blubber to keep their vital organs warm like the warm-blooded whales do.

Whale sharks have a fusiform body – meaning they are wider in the middle – and their heads are wide and flat. They have small eyes, and are believed to have poor eyesight but an excellent sense of smell. They have the same vibratory sensing system running from the top of the head to the tip of the tail as all sharks do to help them locate prey and navigate.

 

Feeding, Funnels & Filters

Whale sharks do not attempt to eat humans – in fact, they aren’t even predatory hunters like some of their distant cousins. Rather, they are filter feeders who open their enormous mouths as they swim through the water to ingest hundreds of pounds of plankton each hour.

They suck in vast quantities of water between 300-500 rows of tiny teeth as they feed, which is then filtered out through their gills. As they do this, food gathers in a ball at the back of their throats. They sometimes make what looks like a coughing motion to get rid of food bits that have stuck in their gills.

Whale sharks are extremely patient feeders – individuals have been recorded to wait as long as 14 hours for fish to spawn on reefs in order to eat their eggs. Whale sharks are often surrounded by schools of fish that use the sharks’ bodies as shields from other predators, because in general the whale sharks don’t attempt to eat fish themselves.

However, the whale sharks living in Indonesia are known to suck fish from nets that fishermen hang under fishing platforms. Many researchers believe that these nets – along with the buckets of fish that fishermen feed them – are one reason why whale sharks gather and stay in this part of the world.

 

What We Know – Behavior and Temperment

From 1828 until the mid 1990s there had only been 320 recorded whale shark sightings in the wild. Although sightings and the pace of research on these enormous, peaceful fish have increased over the last couple of decades, they remain relatively enigmatic, with much still to be discovered about them.

Little is known about their social and mating behavior. In a project based in Cenderawasih Bay where many whale sharks have been tagged for study, researchers have recorded them diving to incredible depths. Why they do this, like so much of their behavior, is still unclear.

It appears that most whale sharks are true gypsies of the ocean, gathering only briefly to conduct social and reproductive needs before continuing on their world travels.

Although mostly solitary creatures that migrate vast distances, they have been recorded as living within distinct groups of age and gender: for example, pregnant females gather in large numbers near Taiwan, and all of the tagged whale sharks staying in Cenderawasih Bay are adolescent males.

Despite their enormous size, whale sharks are docile and gentle. They seem unbothered by divers, whose only danger around them is accidental collision as they swim together in the bays where they congregate. They are intelligent creatures who display an ability to learn – in captivity, they swim in circles when they see their human caretakers coming to feed them.

 

Reproduction – An Unexpected Discovery

Whale Sharks are ovoviviparous, which means they produce eggs but retain them inside their bodies until they hatch. Researchers discovered this fact in 1996 when they found over 300 embryos in varying states of hatching inside a captured female.

When researchers examined the pups, they discovered another interesting fact – every embryo was fathered by the same male. Researchers have theorized from this that females have the ability to store semen and use it to fertilize successive batches of eggs.

It appears that females gather in specific areas to give birth – for example, around Darwin Island in the Galapagos. Researchers don’t yet know the survival rate of whale shark pups.

Although it’s uncertain exactly how and where whale sharks mate, researchers know that they don’t reach sexual maturity until around age 30. Because of this, the catch of a single pregnant female has an enormous impact on the whale shark population as a whole.

 

Habitats and Migration – Ocean Wanderers

Whale Sharks can be found in multiple locations throughout the world’s oceans. They swim in both deep and shallow waters, enjoying coastal areas where food sources are abundant. Genetic research suggests that whale sharks mix genes from far-flung geographic locations, and that two large meta-populations exist – one in the Atlantic and one in the Indo-Pacific.

Researchers are still attempting to discover where whale sharks travel, and under what circumstances. Some stay within a local range – as in Triton Bay – and some travel vast distances. During a 2007 Australian research project, a mature female traveled over 7,000 km (4,350 mi) before her tag stopped working. Four years later, the same female – identified by her unique spot pattern – returned to her original starting point.

How do they navigate with such poor eyesight? Researchers theorize that they orient themselves by reading the alignment of earth’s magnetic field – possibly related to their sensory abilities and to specialized organs which pick up pulsations such as volcanic vibrations and electromagnetic signals.

An ongoing tracking project in Cenderawasih Bay, where most of the area’s whale sharks remain year-round, recorded in December 2005 that two sharks left the Bay and swam towards the coast of New Guinea, while some others headed out toward the Pacific – with some of them swimming up to 4,000 km (2,485 mi) away.

Each of the migrating sharks returned to Cenderawasih Bay soon after making these vast journeys, which researchers have dubbed ‘field trips’ due to their short duration. It’s not yet known why the sharks embarked on these field trips – many were immature males, so it wasn’t for mating purposes. It remains yet another intriguing mystery of the enigmatic whale shark.

 

How Tourism Can Assist with Preservation

In 2015, the IUCN Red List updated the whale shark’s status from vulnerable to endangered. It is thought that their numbers have decreased by 50% in the last 75 years.

Whale Sharks are protected by CITES – the Convention on International Trade in Endangered Species of Wild Fauna and Flora – which is an international government agreement to ensure that trade doesn’t threaten wild species’ survival.

Unfortunately, Taiwan isn’t a member of CITES and whale sharks are extensively hunted there. Conservationists warn that there is a real danger of them being ‘eaten to extinction’ in this area, especially if this is where females gather.

Whale shark hunting is not only happening in Taiwan, though. They have often been hunted elsewhere in Asia on a small scale for their liver oil, which is used to waterproof boats. Fishing fleets target them for their white meat and fins, which are used are for bold decorative pieces designed to lure customers into shops.

Small-scale fishermen hunt whale sharks to sell them for as little as $50 each at the local level. Fortunately, this small amount earned for killing one of these unique, endangered animals can be matched many times over by tourists who pay to observe the awesome whale sharks in the wild.

Dr. Simon Pierce of the Marine Megafauna Foundation (MMF) and Member of the IUCN Shark Specialist Group promotes whale shark eco-tourism and preservation projects that are funded by tourism. He encourages people to dive with whale sharks and get as involved in their conservation as possible. Spreading information about these beautiful creatures and supporting local economies which preserve rather than hunt them could prove vital to ensuring whale shark survival.

One area where such a concept is beginning to pick up pace is Triton Bay. As with the better-known Cenderawasih Bay, Triton Bay’s fishermen have begun to build long-term symbiotic relationships with the area’s whale sharks, setting up fishing platforms where the sharks come to feed and tourists pay a moderate fee for the experience of feeding them, which in turn supports the local economy.

 

Triton Bay – Still a Well-Kept Secret

Triton Bay and the nutrient-rich waters around Kaimana – over 6,000 sq km (3,700 sq mi) – were declared protected by the Kaimana Regency in 2008 due to its incredible array of marine biodiversity. Some call it a miniature Raja Ampat.

Triton Bay’s underwater landscape is home to oversized corals, pygmy seahorses, cow-nosed rays, batfish, ghost pipefish and wobbegong sharks and has been called “the next frontier of Indonesian diving”. Although the nutrient-dense water can make visibility less clear than at other dive sites, it also means the flora and fauna here is large and diverse.

In the last few years, thanks to the fishermen outposts, whale sharks have become an amazing addition to this already vibrant area. If the experiences of the research teams in Cenderawasih Bay hold true here, the growing population of whale sharks in Triton Bay holds great potential for future research.

The area’s relative ease of accessibility, abundant marine life and awesome underwater features, combined with the opportunity to feed and dive with whale sharks – and to contribute to their conservation and the local economy – have made Triton Bay the new best-kept dive secret in Indonesia.

 

Tips for Whale Shark Sightings

Sites within Triton Bay where whale sharks tend to stay close to the fishing platforms are the most reliable and non-impacting places to see these magnificent creatures in the wild.

Some people are wary of whale sharks due to their size and species, but they have never been recorded as acting aggressively toward humans. Despite their enormous mouths, there’s no need to fear being swallowed – but one should nevertheless always keep a safe distance of at least a few meters.

They are gentle, docile fish that show interest in humans, at times even becoming playful with divers. However, because startling them could lead to sudden movements and accidental collisions, it’s better not to get too close. Don’t ever attempt to touch, ride or chase them, and keep your movements calm.

Whale sharks may approach you out of curiosity; if so, enjoy the moment, stay relaxed and you will undoubtedly forever remember the magical experience of a close encounter with a gentle, magnificent, larger-than-life sea creature.

 

WHALE SHARK GALLERY

 

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