Monday, February 20, 2012

News Update ‘Philippines may be breeding area of whale sharks’

THERE’s very little data on whale sharks (Rhyncodon typus) in the Philippines, but what researchers have on the biggest living fish in the world point to enforcement of stronger protection and better management regulations in the country.
Elson Aca, World Wildlife Fund (WWF) consultant who works with the Large Marine Vertebrates Project (Lamave) of Physalus, said there are two significant findings from studies on whale sharks in the Philippines.
One is that whale sharks that were identified, so far, in Philippine waters—whether in Donsol, Sorsogon or in Oslob, Cebu—have never been recorded in international databases before.
This means the whale sharks found in the country’s territorial waters have not been seen and identified anywhere else in the world.
The other factor, Aca said, was that researchers found baby whale sharks that were as small as 64 centimeters in the Philippines.
Whale sharks of this size have just been born, he said.
More significant
“This could mean that the Philippine waters are possible breeding grounds for whale sharks,” he said during a forum attended by biology students of the University of San Carlos (USC) last week.
“Based on these initial findings, waters around the Philippines could have more significance in the conservation of whale sharks,” he said.
Aca said a total of 393 whale shark sightings have been reported in Philippine archipelagic waters.
In a research on whale sharks in Donsol between 2007 and 2011, 80 to 170 individuals have been identified with a re-sighting rate of 50 to 70 percent.
Researchers reported sighting nine to 18 whale sharks a day. The longest stay of the whale sharks in Donsol was 153 days.
Apart from those in Donsol, 17 whale sharks have been identified in Leyte, 10 in Cebu (Oslob), four in Bohol, and one each in Palawan, Batangas and Albay.
Aca said male and female population is almost the same.
Another significant finding is that there are many adult-size female whale sharks in the Philippines. This means many female whale sharks swimming in Philippine waters at a certain time may be of reproductive age.
Since whale sharks are slow to mature, it takes time for females to reach reproductive age.
Whale sharks, often known as gentle giants of the sea, are the largest existing fish species with total recorded length of up to 18 meters.
They are highly migratory and stay in tropical waters, except the Meditteranean. The movements of these filter-feeders are dictated by food pulses.
Although they feed mainly on planktons, the largest recorded aggregation of whale sharks in the Mexican Peninsula in 2009—about 420 individuals—was reportedly caused by a dense patch of fish eggs (Rafael de la Parra Venegas, et. al.).
Aca said whale sharks are difficult to study because of their migratory nature and the high cost of satellite tags.
Whale sharks are also known to stay in the deep most of the time so even those that have been tagged get off the research radar most of the time. (The satellite picks up the location of the tag only when the sea creature goes up to the surface of the water).
Dr. Allesandro Ponzo of the Lamave Project said the average sizes of whale sharks in Oslob are from six to seven meters while those in Donsol are from seven to eight meters.
Lamave Project of the non-profit group Physalus has been studying the whale sharks in the Bohol Sea. (Cebu and Bohol is divided by the Cebu Strait, which opens to the Bohol Sea in the south.)
Ponzo said they plan to study the genetics of whale sharks in the area next month.
In 1999, Lamave Project found that the whale sharks in the Bohol Sea traveled to Vietnam.
Ponzo said Oslob is part of the normal migration path of the whale sharks and the creatures might have been attracted to the presence of food off Tan-awan.
But Aca said the practice of Oslob fishermen of feeding whale sharks is detrimental to the sea creatures.
While the fishermen may mean well, he said, whale sharks should not get accustomed to the presence of boats and people.
He said a whale shark was wounded by a spear in December last year, “which would not have happened if its behavior had not been changed.”
Besides, he said, Oslob fishermen would soon find they are out of feeds for the sharks.
Joey Gatus of the USC biology department said Tan-awan, Oslob fishermen sometimes go as far as Moalboal to catch krill or small shrimps, which they use to feed the whale sharks.
Aca said that while he discourages feeding whale sharks, he is not against tourism.
“But tourism has to be sustainable. Proper management mechanisms and strict enforcement have to be in place,” he said.
He said local government officials and fisherfolk in Oslob are off to a good start by having a briefing and guidelines for tourists. “But there’s a lot of room for improvement, especially in the enforcement aspect,” he added.
For instance, he said, a whale shark warden should be in the water to ensure that all of the tourists watching the sea creatures are complying with interaction regulations.
Aca said local communities can still earn from the presence of the whale sharks without feeding and touching the sea creatures.
He said in Donsol, Sorsogon where feeding and touching the sharks are not allowed, the whale shark tourism industry contributed P82 million to the government income in 2010. The previous year, whale shark tourism revenues in Donsol reached P70 million.
Aca urged local governments and fishing communities where whale sharks are sighted to study and adopt best practices in whale shark tourism management.
In the case of Oslob, he said, there is a need to gather baseline data and conduct more studies.
“The lack of knowledge hinders effective protection of the sharks,” he said.