Sparkle-Clean Sharks: thresher sharks practice good hygiene in the Philippines

As marine biologists continue to study the physiology and behaviors of sharks, we are learning more and more about these fascinating creatures and what we can do to protect them if it's not too late. Case in point:

Thresher sharks have been greatly depleted in number - caught for their fins and meat - which is disappointing over and above the obvious loss in population because it is a very unique species. The thresher shark's namesake elongated tail fin has been shown to be used as a hunting tool, slashing and stunning its prey. Diver encounters with thresher sharks have always been scarce as they often swim in deep, open waters and don't typically congregate in large groups.

However, off the northern tip of Cebu in the Philippines, a dive tourism business is growing based on the thresher shark. Apparently, a concentration of thresher sharks frequent a seamount there, which increases the opportunity for divers to see these beautiful sharks in the wild.

Researchers from U.K.'s Bangor University have been studying the behavior of these sharks in the Philippines and have recently published their findings in the journal PLoS One. According to the research team, the thresher sharks are frequenting the deep seamount to get a good cleaning. Residing at the seamount are a number of cleaner wrasses, a fish well-known for cleaning larger reef fish by picking away parasites and dead skin or scales. It seems that thresher sharks have caught on to the benefits of this hygienic service and will cruise close to the seamount, slowing down to half their normal speed and allowing the cleaner wrasses to give them a thorough once over.

The researchers have filmed this behavior, amassing over 1,000 hours of footage. They are quick to point out that mankind can have a disruptive effect on this symbiotic relationship - the seamount already shows evidence of dynamite fishing, a local commercial technique that literally destroys reef communities.

According to lead researcher Simon Oliver, “Our findings underscore the importance of protecting areas like seamounts which play an important part in [the sharks'] life strategy to maintain health and hygiene.”

Fellow researcher Dr. John Turner said, regarding their studies, “The work uniquely describes why some oceanic sharks come into coastal waters to perform an important life function which is easily disturbed by man.”

A Thresher's Tale (Tail): video footage solves a shark's mystery

One of the ocean's most unusual sharks, the thresher shark, has carried with it a great mystery: why the elongated upper caudal (or tail) fin? Suspicions were that it was used to strike and stun its prey. However, there wasn't any definitive documentation (ie: video or motion picture footage) to confirm it. Until now. . .

According to the BBC News, Dr. Chugey Sepulveda of the Pfleger Institute of Environmental Research in Oceanside, California, captured some brief images of a thresher shark swatting several smaller fish and stunning or outright injuring them, making them easy prey.

The water visibility is a bit murky and it all happens in a blink of an eye, but the video slows it down to half speed and you can clearly see the shark's unique hunting ability. The BBC doesn't allow for embedding a video, so click on the image below to link to the BBC and view the footage.

Followers of great white sharks at Isla Guadalupe are very familiar with the Pfleger Institute as they were one of the first organizations to do an exhaustive picture cataloging of the island's population of white sharks that migrate there every fall.

Kudos to the Dr. Sepulveda. These are very special sharks - all three species of thresher sharks are listed as "vulnerable to extinction" by the International Union for Conservation of Nature (IUCN).

Thresher Shark: non-profit dedicated to shark's preservation

Speaking of sharks, here's a species you don't hear too much about and yet faces imminent danger: the thresher shark.

One of the more unusual and distinctive sharks due to its namesake elongated upper caudal fin or tail, it is believed that the shark might use its tail as a hunting device to stun schooling fish. The thresher shark is a popular seafood item in many forms - fresh, dried, salted - and so it's numbers have suffered (all three thresher shark species are listed as "vulnerable" by the IUCN).

Here's a post from the Shark Divers blog, discussing one of the few shark organizations devoted to the thresher shark. Based in the Philippines where considerable local fishing, commercial and, sometimes, illegal fishing takes place, this group has their work cut out for them.

Thresher shark research & conservation project

Of the myriad of shark conservation sites worth visiting, none come better then the Thresher shark research & conservation project.

We have been following this site for the past year and are always happy with the vibrant field updates, images, video and news.

Consider taking the time to get to know the team behind the Thresher shark research & conservation project.

Shark conservation efforts are hard enough to get traction with; in places like the Philippines, it's doubly so.

It's takes determination, good outreach, and a serious research program to make a difference.

ICCAT: Putting Atlantic bluefin tuna conservation in its grave

Just a few days ago, I posted some hopeful information regarding proposed limits or regulations on Atlantic bluefin tuna and several shark species (see posting). A meeting was being held in Morocco by the International Commission for the Conservation of Atlantic Tuna (ICCAT). It seems by the end of the meeting those hopes were dashed.

The ICCAT has chosen to ignore the advice from their own scientific advisors and agreed to reduce the annual catch from 27,500 tons to 22,000 tons for 2009. The scientific advisors presented data that showed that a catch of 15,000 tons was necessary if the species was to be preserved. Once again it seems short-term economic gain has won out over long-term conservation management. Considering that negative economic impacts on commercial fishing are not something that nature has ever given much of a damn about, there are those who believe that the ICCAT's action could seal the fate of Atlantic bluefin tuna.

Xavier Pastor, Executive Director for Oceana in Europe, declared: "ICCAT’s credibility has been destroyed by the negotiating countries who opposed responsible management measures for bluefin tuna. Instead of preserving the bluefin tuna stock from collapse, they gave in to the fishing industry’s short-term economic interests. With this decision, we can only wait for the disappearance of bluefin tuna."

Also under consideration were regulations regarding the taking of several depleted species of sharks. The only regulation to pass was the releasing of bigeye thresher sharks. (Read Oceana press release.)

To modify Starkist's old advertising slogan, "Sorry Charlie", which promoted discriminating tuna quality; it seems the ICCAT wants to say "Sorry Charlie, nice knowing you."