A Whale Shark
Photo Courtesy of David Rowat
November 19, 2002
The Threats to Whale Sharks
This is Genevieve Johnson speaking to you from the Odyssey in the Seychelles.
At present, nearly all of the research conducted on whale sharks is in coastal areas. In the Seychelles, this means only immature males are being studied - females and adults do not seem to come in to the shallow areas. This is an issue that needs to be addressed as we have virtually no idea about what the population is doing out in the open ocean.
Almost eight years ago it became apparent that a fishery was targeting the Indian Ocean whale shark population. It is unknown whether annual harvests off the coasts of India and Taiwan are having a detrimental effect on the population. India alone takes over 500 whale sharks annually.
David Rowat of the Marine Conservation Society of Seychelles (MCS) is concerned that humans may be adversely effecting the population before anyone has had a chance to learn more about them.
In the second part of our interview with David, he discusses why we need to learn more about the population as a whole and what he believes are the current human, as well as the natural threats to whale sharks.
DAVID ROWAT - Marine Conservation Society of the Seychelles
Where is it going long-term? I think that once we have an understanding of what the shark's reproductive biology is like, what is happening in terms of where the adults are, what is happening in terms of where the females are, then we will have a much better picture of what the actual population is like, because right now we are looking at a very fragmented part of it. Once we have a clearer picture of the population, we will know if we have to have any form of radical, conservative action to protect them or not. And, that really isn't clear, we just don't know enough about the size of the populations and what those populations do at this moment.
The accepted human threats [to whale sharks] are the targeted fishery, on the one hand, while a minor human threat is the threat of ecotourism and whale shark encounter programs. If we look at the fishery aspect, the whale shark fishery is mainly for meat. The whale shark fin is not good for the shark fin soup industry. Shark fin soup is made from the cartilage fibers that run through the fins. Whale sharks have got very large cartilage fibers that are not particularly brilliant to make shark fin soup from. However, as a curio value for shark fin soup restaurants, and there is a lot of that, one very large set of fins was recently sold for a phenomenal amount of money just so they could be displayed in the restaurant, you know, as a promotional thing - “we have the world's biggest shark fins.” But in terms of actual volume, no it's not one of the sharks targeted on a regular basis by the finning industry. It's a very difficult shark to fin. The smaller sharks that you pull onto a boat, you can cut the fins off very quickly and toss the carcass over. Pulling up anything from 7 - 35 tons of whale shark is a whole different project, so it's mainly for the meat.
The reality is that whether an animal is viewed as a food species or not, if it's conservation status is threatened, it needs to come under the terms of CITES (Convention for the International Trade in Endangered Species).
In terms of the eco-tourism side, that's very difficult. Any encounter program whether it's with a whale, a shark, anything that affects the way these animals behave in their natural environment, anything that changes the way they behave, has to be looked at very carefully. Yes, it is a magnificent feeling getting in the water with a whale shark, the same as getting in the water with a whale or even seeing sharks underwater anywhere. My own feeling is that it needs to be as natural as possible, and you want the behavior pattern to retain as much as the natural rhythm as it would normally so you don't change what the sharks are doing. There does have to be a little bit of flexibility on the way that these things are done. A lot of whale sharks, being a shallow swimming species pick up damage from boats. But there is also the threat that you love them to death and the animals begin to suffer as badly from the people who are trying to support them as the people who are trying to harvest them.
Photo: Chris Johnson
When a whale shark is born it is about 78 centimetres long, just under a meter. It's totally defenceless, so you have got a tiny little shark that is absolute food for anything that is big enough to take it. So it seems from the work that has been done within other fisheries, that these very small whale sharks are all very deep-water pelagic sharks. They stay well away from the coast, because everything eats them. So thereby, staying in deep water where the chances of meeting bigger predators is far less and where there is adequate food for them, they're able to bulk up and grow bigger until they are at the 5-6 meter size. At about that size they can start coming into shore again. There is very little that is going to attack them. We do know that Orcas (Killer Whales), take whale sharks. That has been recorded on film and they will take quite big ones. I think that is probably an unusual occurrence.
Small whale sharks have been found in the stomachs of a number of sharks and a number of big billfish like swordfish, marlin, and big sailfish. So they are a good food source. You have got quite a few [whale] sharks with bite marks out of their fins, missing pectoral fins, missing dorsal fins, which for us are useful identification tools that show that life as a young whale shark isn't 'all a bed of roses' so to speak.
The early years of a whale sharks life are quite treacherous, as we have learned. However, we can ensure that the human threats to whale sharks in their mature form are reduced as much as possible.
The Seychelles Minister for Environment, Ronny Jumeau, announced at the closing of this year's SUBIOS festival, that Cabinet would be voting on a proposal for whale sharks to be protected in Seychelles waters, a request that had been made by David and the Marine Conservation Society of Seychelles (MCS). We are pleased to announce that since this interview took place, the bill has been passed. This means that whale sharks are now protected in almost eight tenths of their known range in the Indian Ocean!
Written by Genevieve Johnson