The Big Blue

Whale sharks (Rhincodon typus) are AWESOME. I dare you to disagree. As the world’s largest extant fish they can reach a staggering 12 meters in length and weigh up to 21 tonnes. Now tell me that’s not impressive. Either way, if you love them, or would love to see them turned into mega sushi, you can’t deny that a recently published paperin the open access on-line journal PLOS ONE this week is a little nugget of gold in a whole ocean of shit. It documents a newly discovered major aggregation site for this massive animal in the heart of one of the hottest most inhospitable regions on earth, the Arabian Gulf. For once a good story filtering out from the normal barrage of depressing marine news of over fishing and shark finning.
Ocean babe. And the sharks not too bad either Photo by (so OK, I lost the source for this photo, my bad. If found, please return to the comment section below)
Now when most people think of this region, they think of sand, heat and, well, more sand. But as more research is done into this region, and as technology used to monitor wildlife is becoming cheaper and more accessible, researchers are beginning to get a glimpse into this oft over looked area. And they’re beginning to reveal its rich and diverse natural history. From leopards (Panthera pardus ciscaucasica) and cheetah (Acinoyx jubatus venaticus) prowling the deserts of Iran, to wolves (Canis lupus arabs) and hyena (Hyaena hyaena) competing in the hills of Yemen, to humpback whales (Megaptera novaeangliae) feeding off the Arabian Peninsula, there’s far more to this region then first meets the eye.
And so, 90km off the coast of that tiny nation which owns Harrods and bought the 2022 World Cup, hundreds of sharks have been found to gather in Qatari waters near the off shore platforms in the Al Saheen oil field.  Whale sharks are known to aggregate in large groups all around the world, from Mexico, to Mozambique, to Western Australia, in response to seasonal increases in plankton, but they often occur close to the shore and on reefs. Despite being the largest fish in the oceans, a lot less is known about their behaviour offshore.
The researchers used a number of techniques to study a number of different aspects. Mainly they used observations by the workers on the platforms to estimate the number of sharks seen each week, as the platforms were able to give 360° views of the gulf. But they also did boat based surveys, during which they recorded an unbelievable density estimate of up to 100 sharks within 1km2. Impressive by any standards.
Community gathering (A gaggle? A pack?) of many whales. Photo by Mohammed Al Jaidah
On top of density estimates, they also looked at causes for this mass gathering. It was evident by their behaviour, swimming slowly on the surface, that these animals were feeding, but feeding on what? In other places whale sharks have been shown to feed on plankton, krill, crab lavae, and even small fish by filter feeding. Here though, it turned out that they were feeding on a mass spawning event, they were munching up the eggs of the mackerel tuna (Euthynnus affinis).
This then raises the question of why large numbers of mackerel tuna have decided to spawn in the middle of an oil field, surrounded by eight different platforms?  Amazingly, but perhaps not surprisingly, these platforms might actually be the key. It has been suggested that offshore platforms in Mexico act as artificial reefs which attract spawning fish and thus the sharks, and it’s possible that the same effect is taking place here, increasing the biodiversity around the platforms compared to areas further out. This is supported by observations by platform workers and the researchers of other marine megafauna around the platforms, such as large pods of dolphins (Stenella longriostrisand Tursiops aduncus), 3 species of sea turtles, 2 species of sea snakes and schools of scalloped hammerhead sharks (Sphyrna lewini).
Unconventional guardian. Photo by Warren Baverstock
So this oil field may actually be indirectly benefiting the sharks, and in more ways than one. As well as providing a breeding ground for their prey, the restriction of boats entering this zone (due to operational and security reasons) may also be acting as a sanctuary for the giant fish as they are partially protected. So despite these incredible animals gathering around oil platforms, which I think I speak for most when I say are often regarded with great suspicion, especially when mixed with a marine ecosystem, this might be one natural phenomenon which exists and will persist precisely due to their presence.
If this has peaked any interest in Arabian wildlife, then I heavily suggest you get on and watch the BBC programme ‘Wild Arabia’ which was broadcast a few weeks ago. Fantastic stuff, as we’ve come to expect from the BBC Natural History Unit. They went out to film the whale sharks for the last episode of the series, and got some awesome footage of the artificial reefs, the fish they attract, and evidently the beauts themselves. There are also some more amazing photos of the Qatari sharks, including photos of the artificial platform reefs from the Beeb.
Over and Out.
And finally (Urgh, seriously, I’ll shut up eventually), hot off the press! This photo is an incredibly rare sight indeed. It shows a baby whale shark (think just 30cm long, all together now….) spotted in St Lucian waters by the team at Scuba St Lucia. According to those clever scientists at the Marine Megafauna Foundation who deal with this stuff on a daily basis with the amazing work they do based in Mozambique, there have only ever been a couple reports of baby whale sharks worldwide, so this was truly an AMAZING spot.
Teeny weeny! Photo by Scuba St. Lucia

About zoologyknowledge

Shortlisted for the Wellcome Trust Science Writing Prize 2013. Graduate Biologist with an interest in sharing science news and stories. Special interest in rainforest ecology.

Posted on March 21, 2013, in Uncategorized. Bookmark the permalink. 2 Comments.

  1. Went snorkeling with these guys in Mexico. They are indeed awesome! You can almost get close enough to touch them and they don't seem bothered at all. Unfortunately the underwater camera was not as happy underwater as advertised so photographic evidence is limited.

  2. They are indeed beauts. Possibly one of my all time favourites, so you make me mega jealous with your Mexican escapades! Eeeek! That sounds a tad disastrous, drying out worked… I hope?!

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s

%d bloggers like this: