Bull Sharks on Chumphon Pinnacle ?

Enregistré depuis: jun. 2007

Their have always been rumors about bull Sharks around Chumphon Pinnacle during the past ten years that I've been diving on Koh Tao. Here and there a Dive Master or Instructor claimed to have seen a Bull Shark cruising around the best dive site of Koh Tao. Mostly they got laughed at like myself a couple of times. Now it turns out that the sharks on Chumphon Pinnacle are in fact ALL Bull Sharks!

Richard Campbell and Robin Nagy state in their article:

Citation

The confusion at Chumphon might be that people are muddling sub-adult bull sharks with fully grown Grey reef sharks. This is perhaps unsurprising given the fact that both sharks share both the same family (Carcharhinidae) and genus (Carcharhinus) It is now clear to us that all the sharks we have ever seen on Chumphon Pinnacle have been juvenile to small adult bull sharks and definitely not Grey reef sharks.

Read the whole story here:
Now this surprising fact should not keep us from diving with the sharks but to be more respectful towards these kings of the sea. We should keep in mind that they are at their home and we are the visitors. No one would go into ones house and make all kinds of noises to get attention - he would simply be kicked out - And you don't want to get kicked out by a Bull Shark!

We are very fortunate to have the chance to dive with Bull Sharks on maybe the only place in the whole world where this is possible at depth. Literally thousands of scuba divers dive with these sharks on Chumphon Pinnacle every year. Knock on wood, we never had an accident or even a scary encounter here.
Let's keep it that way by being responsible scuba divers.

We will keep you posted on this website about the newest development on Chumphon Pinnacle. If you have a story to tell or you shot a good picture from a shark please post it here.

Koh Tao Thailand - Projects, Events and Information

Enregistré depuis: jun. 2007

Letter from Robin Nagy:

Encouraged by Geremy Cliff from the Natal Sharks’ Board, South Africa, we intend to create a database of the bull sharks on Chumphon with a view to conducting a research project to try to identify individual sharks and understand their residency patterns, so the more (good quality) pictures/ videos we can gather the better. It would be very good if in gathering the photos and footage, divers could record as much detail of the dive as possible and send their name and email details if they want to be credited with the photo. The sort of details which would be useful for the project would be: date, exact location on Chumphon (if possible), depth, approximate length of shark, behavior, water temp, time of day, etc. Clearly only good quality photos where the sharks are clearly identifiable are of interest, although other details such as those mentioned above would always be useful.

If you would be interested in teaming up with us on this, that would be great – well done with all the work you are doing to make people aware of these sharks – I totally agree, they are safe to dive with so long as they are not antagonized or overly-excited by irresponsible behavior. We dived with one Koh Tao company a couple of years ago and their skipper was spearfishing on Chumphon which visibly changed the sharks’ behavior – they became highly excited. The other thing we must try to stop is fishing sharks in Koh Tao – we stayed in Rocky (shark) bay this year and noticed a significant decrease in the black tip reef shark population. We were shown photographic evidence of several dead sharks which had been killed by a fishing trip for tourists from Rocky bay resort – this has got to stop!

Big Pink Shark Website

Koh Tao Thailand - Projects, Events and Information

Enregistré depuis: jun. 2007

To get one more opinion on our Sharks on Chumphon Pinnacle, I've sent some pictures to Prof.Dr. Schwartz, who is a well know ocean and shark expert on the Institute of Marine Sciences in North Carolina.
I have asked him to confirm our findings and have posted his answer below.

Letter from Professor Frank Schwartz
Institute of Marine Sciences
University of North Carolina

Thanks for the pictures. Now that I see the pictures, yes, you have bull sharks. Note the slender body, note important white spot on the first dorsal fin indicating a reef shark. Note the black caudal fin band on the caudal fin, picture 5 of 21, a grey reef shark. The head picture on 15 of 21 is a good bull shark. During other activities, use the characteristics I sent earlier to tell the three species apart. Thanks for letting me review the pictures.

Characteristics:

Bull sharks, Carcharhinus leucas, are a short, stocky, 7-8’ species with very short blunt head; no interdorsal ridge between the two dorsal fins. The first dorsal fin is high, second 1/3 of first height. Teeth are 25-27/25, 12 teeth on each side in lower jaw.

Gray reef sharks, Carcharhinus amblyrynchus, are gray to darker dorsally. No interdorsal ridge; have a distinct light band along the body sides. Young have a black trailing edge to the caudal fin which becomes lighter in old specimens. First dorsal fin tip is white as is extreme rear edge of first dorsal fin. Teeth are 28-30/27-29.

Blacktip reef sharks, Carcharhinus melonopterus, have a blunt head (not as blunt as in bull shark) and not a stocky body. No interdorsal fin ridge. First dorsal fin tip is black as is lower caudal fin margin. Tips of other fin tips may be dark. Teeth 26-28/25.

Koh Tao Thailand - Projects, Events and Information

Enregistré depuis: jun. 2007

I just got an e-mail from Estelle Davies who works as Naturalist for the Jean-Michel Cousteau's Ocean Futures Society. I have asked her to have a look at the pictures of the Sharks that we have collected so far and here is what she had to say:

....the top two pictures are indeed what seems to be the bull sharks. This is very exciting for Koh Tao since there are very few places in the world (the Bahamas are one) where you can dive alongside bull sharks. Gray reef sharks are thinner and not as bulky as bull sharks. Gray reef sharks also have a black outline to trailing edge of their caudal (tail) fin and a black tailing edge of their pectoral fins.

It is great work what you are doing with the shark datebase and the clam conservation project also.

Best fishes,
Estelle

Koh Tao Thailand - Projects, Events and Information