And the Whale Shark Sightings Begin...

As whale shark sightings become more common on Koh Tao, more and more people come to our little island in hopes of seeing these gentle giants. But how much do we really know about whale sharks?

Turns out, not much. Very little is known about whale shark behavior, migration patterns, and reproduction. 


Here’s what we do know:

Whale sharks have a life span of around 80 years. With this comes slow growth, late maturity, and low fecundity, meaning that when they have offspring it’s in low numbers. The biggest fish in the sea, whale sharks average 10 meters with the largest confirmed stretching 12.6 meters in length. They filter feed on plankton, krill, and larvae in the water column. Often times these sharks are spotted with remoras, or sharksuckers swimming on and around them. These fish hitch a ride and feed on parasites and food scraps.

Though whale sharks spend much of their time in pelagic waters, meaning the open ocean, they tend not to reside in areas with significant depth. Koh Tao’s shallower waters and diverse ecosystem make our island a biological hotspot, however it’s still unclear why such large numbers of whale sharks come to the island. Koh Tao conservationists guess that the sharks might use the area as a pathway to somewhere else.

Sadly, whale sharks are no exception to the many threats that face sharks. Shark fins are in high demand in the black market for Chinese medicine and for the commodity of shark fin soup. Additionally, as many tourist companies continue to feed whale sharks to provide “authentic” encounters for their customers, whale sharks begin to associate food with boats. This results in an increase of boat-related injuries and mortalities as whale sharks associate boats with food and approach other boats, get hit by propellors or caught in nets. 

However, if done correctly, shark-centric tourism may actually work in favor of whale sharks. In terms of shark fishing, on average, a bowl of shark fin soup sells for $100 USD. When compared with the estimated 1.9 million dollars a whale shark can bring in revenue over the course of its life, there is a much greater potential benefit associated with using the shark for tourism than for its fins.

Granted, with this focus on tourism would need to come a shift in the regulations of whale shark tourism to minimize behavioral changes—no feeding the sharks and keeping the proper distance. However, it’s this change of perspective on traditional practices and re-education of a more sustainable industry that will make a lasting impact on the population of this endangered species.

Koh Tao Specifics:

Based on data collected by conservation instructor Kirsty Magson, around Koh Tao alone, from January to October of 2017, there were over 75 recorded whale shark sightings (sometimes more than four sightings in a day!). These were some of the highest numbers in the entire Gulf of Thailand. Of the local dive sites, the greatest number of sharks were seen at Chumpon, Shark Island, and Sail Rock. 

As the number of divers coming to Koh Tao grows and the excitement about being in the water with whale sharks increases, we have to ask, “How Close is Too Close?” As pictured below in our Code of Conduct, divers and snorkelers should keep three meters of distance between themselves and the whale shark and an additional meter from the tail. These boundaries not only keep divers safe but also give the whale shark necessary space and help keep from scaring it off or discouraging it from coming back to the site in the future.   

Much like a human’s fingerprint, whale sharks have markings that are unique to each individual shark. This enables sharks to be ID’d through photos, specifically photos taken above the left pectoral fin. Using citizen science and crowdsourcing images of local whale shark sitings, Magson has been able to identify 66 individual whale sharks from over 350 different photos. Of these 66, the majority were female and the sharks averaged 3 to 4 meters in length, suggesting they were still young. Once given an ID number, using future photos, the conservation team can see where the shark has been and if it has any habitual patterns. 

How to Get Involved: 

As a Koh Tao visitor, you can help collect information about whale sharks. If you encounter a whale shark on a dive, respect the Code of Conduct and try to get a photo of the left side of its face, behind the gills and above the left pectoral fin. If you submit your images to our Facebook page, Koh Tao Whale Shark, we can use them to ID the shark. Additionally, organizations like record data of megafauna sightings around the globe. Outside of Koh Tao, be conscious when choosing a dive school or snorkel tour, ensure that the company you go with doesn’t feed the whale sharks. Avoid shark fin soup and educate others about the harmful effects of these practices.

Last year brought dozens of whale sharks to Koh Tao, and with them an elevated interest among divers and a whole host of new information regarding our local whale shark population. Our hope for the future is to get more people involved and excited about whale sharks and involved in the conservation of not only this wonderful species but of our marine world on a larger scale. Furthermore, we aim to gather more data about these sharks to help us better understand their behavior and therefore the best way to preserve their habitat and to share our knowledge with others. 


Photos were taken by conservation instructor Kirsty Magson. To learn more about our marine conservation program click here!

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Phone: +66 (0)77 457045 or + 66 (0)91 8324800
48 Moo 3 Chalok Baan Kao
Koh Tao, Surat Thani
84360 Thailand

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