Ragged-tooth (sand tiger) sharks are a thrilling shark to dive with. Commonly seen moving slowly and menacingly through aquariums, they always seem to have an eye watching you. In the wild, it’s no different and you can have truly amazing encounters with them if you are slow, controlled and calm.
As part of the warm-up for our first ever Sardine Run in South Africa in June–July, we got to dive with more than 10 individuals on several dives. At one point, I got under an overhang as three sharks made their way into the same area – I was worried that they would get spooked and swim off or that I would disturb their natural behaviour of circling round and round in the “grotto” area at Raggies Cave. However, I kept my cool and they continued to move around in the smaller space, giving me an adrenaline-fuelled dive to remember. It’s intimate experiences like these – seeing this beautiful species in its natural habitat – that fuel the passion for working for Shark Guardian.
Shark Guardian has four main areas of operation: conservation, education, research and expeditions. A big 2016 goal for Shark Guardian was to expand on expeditions and spend more time with sharks. We did just that with the Sardine Run, an amazing wild coast adventure. A highlight was snorkelling within metres of a baby humpback whale. However, I can recall being pumped by so many shark encounters from ducking my head underwater at the tail end of the dolphin pods. We are still unsure if one image caught on video was a juvenile great white shark looking to scavenge on the pieces of sardine left by the dolphins.
Our key focus as a UK charity has always been shark education. With the right education, people can make better choices, and this is all geared to educate people not to buy or consume any shark-related products. Last year, 2016, was once again a busy year for Shark Guardian on the school front. New tours in South Korea and Singapore have increased the number of worldwide countries where we now have a presence. This is alongside ever-increasing events in Thailand, including local schools there (another goal for 2016), as well as expansion in Indonesia. Success with our International Shark Student Ambassador programme has made the Shark Guardian team super proud – more of this to come!
Scuba diving with sharks in Thailand and Indonesia in 2016 was a much quieter year for Brendon (my husband and Joint Director of Shark Guardian) and me. And by that I mean a quieter year for shark sightings as a whole. Our research projects using citizen science – where members of the general public collect data for projects – continue to be vitally important. And not least because two of the three projects we promote were imperative in leading to two shark species being reclassified on the International Union for the Conservation of Nature (IUCN) Red List last year.
Over the last 75 years, whale shark numbers have declined by more than 50 percent, and in July 2016, the IUCN changed whale sharks from “vulnerable” to “endangered” on the Red List. The IUCN Red List is the most comprehensive inventory of all relevant data of the conservation status of plants, fungi and animals worldwide. It uses different classifications to categorise the conservation status of biological species. According to these classifications, whale sharks are now only two steps away from total extinction in the wild.
Since 2013, Shark Guardian has collaborated with whaleshark.org to increase the global database of whale shark sightings in Thailand, as well as worldwide. Through community presentations, workshops, dive centre boat education, and extensive information through posters, leaflets and social media promotions, whale shark ID photos have risen. The data will allow scientists behind the project to better understand whale shark populations in Thailand.
My best whale shark encounter was in 2014. At the end of a dive at Koh Tachai pinnacle (north of the Similan Islands on the west coast of Thailand) only myself, Brendon, a divemaster trainee and the dive centre owner were hanging at a safety stop. Suddenly, one of the whale sharks from earlier in the dive decided to come and hang with us too. A few moments later, a huge oceanic manta ray swiftly dived underneath us all, leaving us wondering where we should focus our attention. The juvenile whale shark swam round us for a good 20 minutes whilst the manta kept doing the same as if to take our attention away from the world’s largest fish. It’s not often you get such a personal interaction with either of these species, and of course for shark lovers like ourselves, we only had eyes for the playful, baby shark!
Whale sharks seen in Thailand are small. Their average reported size is just 4.5 metres (they can grow to 20 metres). Whale sharks reach maturity at around eight to nine metres, and therefore the sharks sighted in Thailand are juveniles. This is not unusual, as most other coastal whale shark aggregations also report a juvenile-dominated population, with average sizes ranging between four and seven metres. The only places where larger whale sharks can be seen are Qatar, St. Helena and the Galápagos Islands, the latter of which has almost exclusively pregnant females, all greater than 10 metres long.
After a very quiet year of whale shark sightings in 2016, we are hoping that the coming months bring us exciting encounters once more in Thailand waters. Through the project we know that most whale sharks are only seen once. This indicates that the sharks in Thailand move through the area, rather than being resident. International protection is thus important for these travelling behemoths and highlights why we must continue to ensure everyone who sees a whale shark gets an ID shot into the database.
In early December last year, a second shark species close to our hearts, the leopard (zebra) shark, also had its IUCN classification changed to “endangered” from “vulnerable”. Zebra sharks (stegostoma fasciatum) are named for the zebra-like stripes they display as babies. Mature zebra sharks are commonly known as leopard sharks due to their spots (not to be confused with the different species of leopard sharks off the Californian coast). Dr Christine Dudgeon, biologist with the University of Queensland and lead scientist on the Spot The Leopard Shark Thailand project that we promote, used data from the project to help bring about this change. It reinforces how important our citizen science projects are, especially in places where we are lucky enough to have one of the few populations left of a declining species.
Leopard sharks were in the news again recently due to their unique abilities in reproduction. Leopard sharks can reproduce asexually. Also known as parthenogenesis, this refers to a female being able to create and sustain a shark pup without a male shark and without ever having mated. This has only ever been observed in sharks in captivity, but might occur in the wild where there is a severe shortage of male sharks.
However, Dr Christine Dudgeon just published research that showed how a female leopard shark separated for years from her mate in an aquarium tank in Townsville, Queensland, gave birth by herself – despite having previously produced around 26 babies with her mate. This is the first time that the switch from sexual to asexual reproduction has ever been documented in a shark and only the third reported case among all vertebrate species.
We always tell people that sharks are amazing and try to share awesome shark facts as well as research like this. Such information continues to reinforce why they truly are apex predators and you get an insight into why they have been in our oceans for more than 400 million years. In future columns, we will be sharing more important research as well as cool shark photos and facts whilst giving you an insight into the ever busy world of Shark Guardian.