Thrashing Thresher Sharks
This pelagic thresher shark, is from the island of Cebu, in the Philippines. Life here can be a real struggle, and too often, nature comes off second best. It's the last place one would expect to find a rare species of shark. Pelagic thresher sharks are occasionally caught in isolated parts in the Pacific and Indian Oceans, but a resident population has recently been discovered in Philippine waters. They're a pelagic species, which means that they roam the oceans. At Cebu, there's an undersea mountain where they're found all year round. From the large size of those eyes it is immediately obvious that this is the type of animal that hunts in deep water or hunts at night.
Threshers perform spectacular leaps out of the water, but you've got to be lucky to catch one on film. They are very approachable at this particular sea-mount and not the least bit aggressive. Males are about eight to ten feet long, with big eyes and big long long tails. That tail is almost half the length of the entire body of the shark. There are a lot of theories about what it's for. Some say it actually used it for stunning prey, but it could equally well be used to herd them. Whatever the reason, that long tail creates a lot of downward thrust. So to balance that, the thresher has long pectoral fins to give some lift.
It's taken a little while to understand why the thresher's are attracted up to the surface from the depths. This area is a bit of a cleaner station and what's happening is that the thresher sharks are coming in and they're circling around this cleaner station. These little fish are coming up and picking parasites off the big predators like the thresher sharks. That's probably one of the reasons why they're here. One of the things that has protected the threshers so far is their preference for the unlit depths. The sharks can probably go 500 feet and deeper.
Thresher sharks are not the only animals that use these cleaner stations. Manta rays are also coming in for a bit of a clean to remove parasites like flatworms and copepods. Animals actually have to queue up to be cleaned. This station is serving quite a large population of sharks, possibly coming from many miles around. These visits coincide with the jumping behaviour. Being cleaned has to be a little bit ticklish, so maybe the sharks are breaching to dislodge the last of their parasites and get rid of that irritation. Observing the pelagic thresher at close range is a rare privilege. The sad fact is that it's probably just a matter of time before this cleaning station receives a direct hit from dynamite fishing and is gone forever.
That may not affect the greater thresher population. As far as we know, this difficult-to-find species isn't endangered. But the chance to study them like this may never come again. However, the situation isn't without a small glimmer of hope. There's no doubt that dynamite fishing threatens to destroy the threshers cleaning station, but not everyone in these parts is out to damage the environment.
A large part of the population here relies on less destructive fishing methods, and most of them know that their existence depends on sustainable catch efforts. Even more positively, tourist diving offers the area a way to earn a living that exploits and maintains the Philippines wonderful marine life.
These still frames are captured from video that NHNZ Images has in its collection, and that is available for you to purchase for your production.