Philippine fishermen, volunteers and authorities with dozens of fishing boats have joined hands in guiding back to sea about 500 disorientated melon-headed whales that were stranded in the shallow waters near the mouth of Manila Bay delta in the Bataan Peninsula.
The gentle mammals were first spotted swimming back and forth and straying very dangerously close (about a mile or 1.6 kilometers) to the shores of the coastal towns of Pilar, Orion and Abucay 135 kilometers northwest of Manila at around at around 4:00 am on Tuesday, said Philippine Coast Guard (PCG) Commodore Luis Tuazon and Bataan Governor Enrique Garcia Jr.
The Philippines Bureau of Fisheries and Aquatic Resources (BFAR) said its has responded to the reported mass "stranding" of whales off Pilar coastal waters in the province of Bataan where the famous and historic Corregidor Island is located. 
Using dozens of fishing boats with machines shut down and bare hands, more than 100 village fishermen and volunteers along with BFAR, local police and Philippine Coast Guard personnel have joined the massive rescue. With great difficulty, the emergency team has waded into the chest-deep water, clapping their hands and hitting the surface to guide and drive the whales farther away from the coastal shore to deeper waters.
"The mammals were at first thought to have been dolphins, but experts then identified them as melon-headed whales," local veterinarian Mariel Flores said. "This type of whale can be easily mistaken for dolphins because of their size and their teeth, which resemble those of dolphins. The mammals have ears that are sensitive to large changes in pressure underwater," she added.
—--Philippine Veterinarian Mariel Flores"It looked like they never wanted to leave. They looked sad,” said Rodolfo Joson, a village councilor. Joson and his son, Joey, a fisherman like him, have rushed home at about 4 a.m. to report the pod sighting. “It was still dark when we waded into the water. The whales were about 200 meters from the shore. The water was up to my neck. We first checked their conditions by playing with them. They did not repel us or leave. They were making hooting sounds,” Joson explained the mass beaching. “It seemed they were running away from waters that they didn’t like. Dolphins are happy and strong creatures. They raced with ships,” he added.
A post-mortem examination has revealed that four dead whales found beached farther up north in Abucay, Bataan, include two adult females, one of which was pregnant, while the other gave birth to a calf that also died, said Dr. Lemnuel Aragones of Ocean Adventure in Subic Freeport who did the necropsy at the Bataan fisheries office in Balanga City.
This is the first time that such large numbers of dolphins had been stranded in the Philippines. "We are trying to come up with a possible explanation to this unusual occurrence. It could be that the dolphins had lost their bearings and inadvertently ended up on the shallow portion of the coast unable to extricate themselves," said Dr Lemuel Aragones, Associate Professor at the UP Institute of Environmental Science and Meteorology. 
Dr Aragones, who holds a PhD on Tropical Environmental Studies (Marine Ecology) from Australia's James Cook University, explained that "the melon-headed whales of the dolphin family have sophisticated navigation systems that operate on a principle similar to sonar instruments used in submarines. Like humans, dolphins also follow a 'leader' of their pod. It is possible that the leader of this dolphin [pod] had somehow lost its way. In turn, the leader’s acoustic system, which serves as its guidance system, might have been impaired," the marine expert elaborated.
Dr Aragones said "BFAR, UPIESM, and the Ocean Adventure Marine Park in Subic started the Philippine Marine Mammals Stranding Network (PMMSN) in 2005 as a response to cetacean strandings or beachings." She cited the PMMSN training received by BFAR officers in Bataan during Tuesday's mass beaching. She has asked the government to release funds for marine mammal studies.
The two adults had damaged eardrums, Alberto Venturina, the provincial veterinarian, said. "Dolphins with injured eardrums become disoriented, cannot dive for food and are too weak to swim and just flow with the current. If it's a sick leader, the animal needs to be identified and taken out of sight of the rest of the pod so the healthy dolphins could be prodded back to sea," he added."The two animals were identified as melon-headed dolphins, weighing about 250 to 300 kilograms (550 to 660 pounds)," explained Venturina, adding "the third dolphin was only a month old and measured barely a meter long. Its gender had not yet been determined."
According to Nelson Bien, head of the Fisheries Resource and Management Division of BFAR Region III, a necropsy by BFAR, the provincial veterinarian, and veterinarians from the Ocean Adventure in Subic Freeport has traced the cause of their death to drowning. 
The marine doctors have determined that the marine mammals might have drowned after failing to extricate themselves from the fishing nets or "baklad," explained Dr. Mundita Lim, director of the Protected Areas and Wildlife Bureau (PAWB) of the Department of Environment and Natural Resources (DENR). “There were no injuries to their ears, like visible lesions, but the possibility of an acoustic problem or trauma is still there,” Dr Lim explained, saying, "more tests, like analysis of tissue samples and MRI tests will have to be done to see if there were other injuries to the animals not visible externally."
They are sending tissue samples to the University of Philippines in Los Baños, Laguna for analysis. “If it was something like climate change, then it would be a bigger environmental problem,” Lim added.
A fourth and pregnant one was also found dead in the village of Tortugas in the town of Balanga, Bataan, said Bien, saying they were investigating the incident and would conduct a “water quality and water parameter test” to determine why the dolphins beached to shallow waters. The condition of melon-headed whale found at Talisay River and taken to Ocean Adventure in Subic Freeport has improved amid forced feeding and treatment of its 2 wounds, said Nilo Ramoso, Biologist III, Pawikan Conservation Project.
Dr. Westly Rosario, BFAR Center chief in Dagupan City, has reported that BFAR personnel were also investigating a “problem in the water, probably chemical pollution,” to explain why the dolphins beached and sought shelter in the shallow waters. The dolphins have faced the same direction and their blowholes above water, they seemed to be avoiding something. “The dolphins were behaving in the same way, they have the same action. People were trying to drive them back into the sea but they refused. There could be chemical pollution somewhere which they were avoiding,” Rosario explained.
Dolphins' disorientation is sometimes caused by the changes in earth's magnetic field “that cause the dolphins’ navigational mechanisms to go haywire,” Dr. Edgardo Gomez, professor emeritus of the University of the Philippines Marine Science Institute, said, adding that "it could also be chemicals in the water that affected the dolphins, although this should be proven by water tests." Philippine marine biologist Rizza Salinas said a possible cause for the stranding of large pods of distressed whales is that there could have been illegal dynamite fishing in the area.
“This is very strange. What is also unusual is they appeared disoriented. I am on my way to Bataan on board BFAR’s patrol vessel. We will look into the situation. Our patrol boats are also on their way to the area. We are also getting experts on stranding," said BFAR director Malcolm Sarmiento Jr. Sarmiento, explaining that the highest number of stranded dolphins recorded by the BFAR was only 20 to 30. "It's something unusual. It's the first time that such a large pod has entered Manila Bay, and is acting strangely," Sarmiento added.
"Most strandings are caused by seaquakes, heat wave or disturbances at sea. Such disturbances affect the pressure underwater, which subsequently affects the dolphins’ eardrums and sense of balance, leading to their "disorientation." The creatures then will avoid diving in deeper parts of the ocean and will swim to shallow areas. They came from the north and were headed towards the South China Sea," Sarmiento explained, adding that the unusual occurrence may have also been caused when the pod could have been following a sick or injured leader.
Sarmiento has appealed to the public not to inflict harm on the dolphins, which are considered threatened species. "Please do not harm the dolphins because they are already endangered. The authorities should also prevent the people who want to inflict harm on the creatures. They should be arrested, if needed." Melon-head dolphins are considered threatened species — meaning they are likely to become endangered in the future. 
"At around 12 noon, the dolphins were finally guided to the open seas, but residents in Hermosa near Mariveles were surprised to see the dolphins near their shoreline, but around 4:30 pm, all the dolphins have left the shoreline and swam towards into deeper waters," said Governor Garcia.
"The dolphins swam parallel back to Abucay, Hermosa, and Manila Bay before they were eventually herded farther offshore. There are theories that this phenomenon was a result of the Monday night lunar eclipse. The Fisheries Bureau will know after their tests,” Garcia added. 
Having suspected the dolphins’ habitat must have been disrupted, forcing them to flee and seek refuge in shallow waters, Senate of the Philippines Majority Leader, Juan Miguel Zubiri on Tuesday asked experts to probe the cause of the sudden appearance of more than 300 electra dolphins near the shores of Pilar town in Bataan province Tuesday morning.
Senator Zubiri wanted the experts to examine the possibility that an earthquake study, involving an undersea experiment using blasting in the South China Sea by the Lamont-Doherty Earth Observatory (L-DEO) - a collaborator of Columbia University - caused the abnormal behavior of the small whales.
Citing an International Union for Conservation of Nature research concluding that the melon-headed whales may have been distracted by the South China Sea study, forcing the dolphins to wander in the shallow waters, Senator Zubiri said that “the earthquake study is a sea floor investigation project in the exclusive economic zone that includes Taiwan, China, Japan and the Philippines for its earthquake research. On top of saving stranded dolphins, we should find the cause for the tragedy in order to avoid them in the future and to be prepared when it occurs again," he explained.
But according to Erlinton Olavare, Philippine Institute of Volcanology and Seismology (PHIVOLCS) science research specialist, “no significant event was recorded by their stations in Bolinao, Sta. Cruz and Lubag, near Pilar at the time the dolphins were stranded Tuesday."
Department of Environment and Natural Resources Secretary Jose L. Atienza, Jr. said Bataan Gov. Enrique “Tet” Garcia on Wednesday confirmed there was dynamite fishing in his province. “I asked him [Garcia] and he confirmed it. He also said he was battling this illegal activity,” said Atienza. “The causes of the acoustic trauma could have been sound waves caused by dynamite fishing or sounds emitted by passing ships or seaquakes,” Gov. Garcia said. 
"Dolphins are a 'cohesive' group and that they follow where their leader takes them. If the leader of the dolphins was sick, then the animal could have committed a “navigational error” and led the rest of the group to shore," said the Whale and Dolphin Conservation Society (WDCS).
"The pod of melon-headed whales (dolphins) on Manila Bay were injured by a rather nasty group of more than 120 undersea earthquakes. The swarm started with a small magnitude-4.5 event on December 21, 2008. Things got red-hot on January 3, 2009 when a magnitude-7.6 event erupted near the water’s edge on Papua Island in Indonesia, 700 miles southeast of Davao City in Mindanao. The 7.6 magnitude quake was followed by more than 120 major aftershocks each one capable by itself of inflicting injury on a pod of dolphins," said Capt. David Williams, a retired marine mammal researcher, a commercial sea captain for 40 years and active whale conservationist. 
Capt. Williams explained that whales and dolphins have small air sacs (pterygoid sinuses) that surround each inner ear and help then sense sound direction underwater. A damaged pterygoid air sac results in the loosing of echonavigation and echolocation. "In summary, my Seaquake Theory indicates that barotrauma, as a result of exposure to potent earthquake-induced changes in ambient pressure, solves the centuries-old mystery of why whales and dolphins mass-strand on beaches around the world," Capt. Williams concluded.
An explosive blast and explosive decompression create a pressure wave that can induce barotrauma. The difference in pressure between internal organs and the outer surface of the body causes injuries to internal organs that contain gas, such as the lungs, gastrointestinal tract, and ear.
According to the Natural History Museum experts, whale and dolphins can become confused, mis-read the Earth's magnetic fields, fear certain sounds and get lost. Since 1913, it has investigated all strandings, more than 11,000 so far, and it runs the UK Whale and Dolphin Stranding Scheme. 
New Zealand's Project Jonah has claimed that the largest recorded beach stranding was in 1918 when 1,000 pilot whales were stranded on New Zealand's Chatham Islands. 
The last mass beaching in the Philippines was in 1956 when around 12 sperm whales were stranded in a coastal area in Capiz, amid at least 10 yearly strandings that happened in the country involving only one or two animals that were either sick or dying.
Last January this year, Filipino fishermen have also rescued an endangered sea cow. The fishermen aided the beached sea cow to the deep sea, according to the Worldwide Fund for Nature.
The Melon-headed whale (Peponocephala electra; many-toothed blackfish and electra dolphin) is a cetacean of the oceanic dolphin family (Delphinidae). As small members of the dolphin
group, it is closely related to the Pygmy Killer Whale and Pilot Whale, and collectively these dolphin species are known by the common name blackfish.
The tender mammal can grow up to 2.7 meters (9 feet) and weigh as much as 210 kilograms (460
pounds). With black triangular “mask” on its face, it appears dark gray to black in color, has no discernible beak and its head is shaped like a rounded melon, thus the name. Its primary diet is squid and fish. The Melon-headed whale lives well off-shore in all the world's tropical and sub-tropical oceans. 
At the northern fringes of its range it may also be found in the warm currents of temperate waters. Ordinarily, however, it is found beyond the continental shelf between 20° S and 20° N. The Melon-headed whale is widespread throughout the world's tropical waters, although not often seen by humans on account of its preference for deep water. It has been found in Ireland, Hawaii and Cebu, in the Philippines.
As social species, they are covered by the Marine Mammal Protection Act of 1972 in the United States. In July 2004, between 150 and 200 melon-headed whales occupied the shallow waters of Kauai island in Hawaii for over 28 hours, after which, they were rescued and guided to deeper water. This incident may have been related to nearby United States Navy sonar exercise. 
The International Union for Conservation of Nature (IUCN) which includes the melon-headed whales in its Red List of threatened species said that the number of whales involved in mass stranding had increased in the last 30 years.
"The melon-headed whales are likely to be “vulnerable” to loud sounds, such as those generated by navy sonar and seismic exploration. Evidence from stranded whales also has indicated that they may have died after swallowing plastic items. It has been predicted that the whales will be affected by global climate change, but the impact is still unclear," the IUCN explained.

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500 stranded melon-headed whales rescued in Philippine bay