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Disappearing marine mammals


Text by Henrylito D. Tacio

Photo: Wikipedia

The word is out: two of the 26 marine mammal species and subspecies found in the Philippines are on the verge of extinction. If nothing is done soon to save the remaining population, they may join the dodo into oblivion. 

The dodo is an extinct flightless bird that was endemic to the island of Mauritius, east of Madagascar in the Indian Ocean. Its closest living relative is the Nicobar pigeon, which can also be found in the Philippines.

The Red List Status of Marine Mammals in the Philippines – the most comprehensive and up-to-date list of the country’s threatened dolphins, whales, and dugong – identified the two marine animals as the dugong (scientifically known as Dugong dugon) and Irrawaddy dolphin (Orcaella brevirostris).

Both are classified as “critically endangered.” This means that they “face an extremely high risk of extinction in the wild.”

“Populations of dugong and Irrawaddy dolphins in the country were found declining despite legislation and conservation efforts,” said Marine Wildlife Watch of the Philippines, one of the leading researchers of the book, in a statement.

“(Both species) continue to face threats such as destruction of habitat, entanglement in fishing nets, solid wastes, coastal development, boat traffic, and sedimentation all made more severe with climate change impacts,” the statement added.

The dugong is locally called baboy-dagat (pig of the sea). It is one of the only four living members of the obscure mammalian Sirenia or sea cows. In the Philippines, a small number can be found in the shallow waters of Palawan Province, Romblon Island, Guimaras Island, and Pujada Bay in Davao Oriental.

The dugongs are more closely related to the elephants than the very fat dolphins, although they are similar in size and shape. Studies done on this species showed they have a life span of more than 70 years but are non-prolific. 

Female dugongs may have their first calves at the age of nine years, marine scientists claim. At times, the pregnancy may be delayed up to 17 years. It takes 13 months before the delivery comes.

Dugong is among the sea mammals found in the Endangered Species Act of the United States. The International Union for the Conservation of Nature and Natural Resources (IUCN) classified it as “vulnerable to extinction” under the 2009 World Conservation Union Red List of Threatened Species.

The Dugong (Dugong dugon): Status Report and Action Plans for Countries and Territories in its Range reported that the slow-moving mammal “appear to have disappeared” or “already become extinct” in some places, particularly “the waters off Mauritius, the Seychelles, western Sri Lanka, the Maldives, Japan’s Sakishima Shoto Islands, Hong Kong’s Pearl River estuary, several islands in the Philippines including Zambales and Cebu, and parts of Cambodia and Vietnam.”

The Philippines is one of the signatories of the Memorandum of Understanding on the Conservation and Management of Dugongs and their Habitats throughout their Range (Dugong MOU). Vidal Erfe Querol, Philippine Ambassador to Indonesia, signed it on behalf of the Philippine government on August 19, 2008, in Bali.

The Irrawaddy dolphin was first described by Sir Richard Owen in 1866 based on a specimen found in 1852. Genetically, it is closely related to the killer whale (orca). It exists in small isolated populations around Southeast Asia.

In the Philippines, the Irrawaddy dolphins are found in Malampaya Sound in Palawan. Researchers are studying the recent discovery of 30-40 dolphins sighted in the waters of Bago City and Pulupandan town in the province of Negros Occidental in Western Visayas.

The Irrawaddy dolphins are thought to reach sexual maturity at seven to nine years, according to studies. Its gestation period is 14 months; cows give birth to a single calf every two to three years. Its lifespan is about 30 years.

In addition to the dugong and Irrawaddy dolphin, 24 other marine mammals found in the country were assessed by at least 20 scientists, experts, researchers, and conservation managers. They based their assessment on the Red List categories and criteria set by the IUCN.

The national marine mammal “Red List” assessment also identified four other marine mammal species as “vulnerable.” These are the humpback whale, Fraser’s dolphin, Gray’s spinner dolphin, and the sperm whale.

Vulnerable are those species and sub-species whose populations are still sizeable but are under threat from serious adverse factors throughout their range. They are believed likely to move to the endangered category in the near future.

Another alarming information: 20 out of the 24 species and subspecies assessed in the Red List Status were found to be “data deficient” as there has not been adequate research on their condition, threats, and capacity for survival. 

“This does not mean that these animals are out of the ‘red’ and not threatened. It just shows that there is an urgent need for more research,” explained Dr. AA Yaptinchay, Director of Marine Wildlife Watch of the Philippines.

According to the press statement, studies on these species are necessary for conservation planning, policy-making on local and international levels, monitoring trends in extinction, and tracking of progress towards conservation of the remaining populations.

“Like the Philippine eagles that have managed to survive in the remnants of our forests, whales and dolphins are barometers of the state of our seas,” wrote Jose Ma. Lorenzo Tan, author of A Field Guide to Whales and Dolphins in the Philippines.

Marine mammals are very important as they share much in common with human beings. “They are the top of their food chain, compete with humans for many of the same food sources, and may be affected by many of the same kind of pollutants or environmental disruptions,” wrote Ed Ayres, a researcher for the Worldwatch Institute.

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