Dolphin-stranding in the Philippines ‘unusually high’

Tonette Orejas Philippine Daily Inquirer 27 Sep 10;

CITY OF SAN FERNANDO – More than 500 dolphins, whales and dugong (sea cows) were stranded on Philippine shores or swam in shallow waters in the last 11 years, producing several hotspots around the archipelago, according to the country’s first database on marine mammal-stranding from 1998 and 2009.

A team of 10 scientists, veterinarians and policymakers put the database together through a grant given by the Office of the Vice Chancellor for Research and Development of the University of the Philippines in Diliman, Quezon City. The international journal “Aquatic Mammals” published a paper summarizing its contents and findings.

Doctor Lemnuel Aragones, the team leader, said the Philippines was in a better situation now because it has a database as well as a response program. These, he said, were “often nonexistent in developing countries.”

Stranding happens when sea creatures that are sick, lost and weak take refuge on shores or when their remains are washed ashore, the team said.

The database documented 178 stranding incidents. In 163 incidents, the sea mammals were found to be alone or a few with calves. In 10 incidents, 36 creatures were seen in groups of two or up to 14. Five “out-of-habitat” stranding incidents, or when animals stayed near shores, counted 370, mostly dolphins in Pilar, Bataan, in February 2009.

On the average, 15 stranding incidents were reported yearly.

The database also included information on illegal fishing practices and environmental changes that caused what the team called “unusually high incidence of stranding.”

“It might be likely that the annual average number of stranding of 15 from 1998 to 2009 represents an underestimate in events because past incidents might have been unreported,” the team said.

At least 116 of 163 individually stranded dolphins, whales and dugong were found alive, a rate considered by local scientists to be high.

These animals might have sought refuge on the beach due to noise trauma from dynamite fishing, interactions with fish or biotoxins from harmful algal blooms, the team said. Countries like Thailand, Taiwan, South Australia and eastern United States had low live stranding cases, it said.

The stranding incidents happened mostly in Central Luzon, Central Visayas, the Ilocos and Bicol.

Zambales, Cagayan, Zamboanga City, Negros Oriental, Bohol, Pangasinan and Bataan are considered hotspots because of the frequency of stranding incidents there.

Some places are also considered hotspots because rare species retreated to their shores.

The Longman’s beaked whale (Indopacetus pacificus) was seen in Davao City. The first recorded specimen of the pygmy sperm whale (Kogia breviceps) was seen in Bulakan, Bulacan, while the highest number of stranding baleen whales was documented in Batangas.

It was through the database that the team validated that 23 of the 28 confirmed species of marine mammals in the Philippines had been stranded. These included the Indo-Pacific bottlenose dolphin (Tursiops aduncus), pygmy sperm whale and Longman’s beaked whale.

The database showed that the top five stranded species were the spinner dolphin (Stenella longirostris), short-finned pilot whale (Globicephala macrorhynchus), melon-headed whale (Peponocephala electra), Risso’s dolphin (Grampus griseus) and common bottlenose dolphin (T. truncatus). Records showed seven stranding cases of dugong (Dugong dugon) since 2001.

Stranding happened throughout the year, but mostly during the northeast monsoon (amihan) season when winds caused strong water current from November to March.

Its members said it was not surprising to see stranded mammals in the country because the Philippine coastline stretches 36,289 kilometers.

The team collected the data from the Bureau of Fisheries and Aquatic Resources, Department of Environment and Natural Resources, nongovernment groups, Museum of Natural History at UP Los Baños in Laguna, the private marine park Ocean Adventure in Zambales and incidents documented by team members.

Too few data are available before 1998, the oldest being that of the stranding of 12 sperm whales in Cadiz City, Negros Occidental in 1967, the team said.

It made a stranding report form to systematize the recording of incidents. It said the database confirmed the diversity of marine mammals in the Philippines and growing awareness of the public to help animals in need.

The database called attention to the plight of the Irrawaddy dolphin and dugong because these have been most endangered by human activities.

The team recommended the continued collection of comprehensive data to reach “greater accuracy in determining the possible causes of stranding [incidents] and the influence of human activities on these events.”

It urged further investigation on the impact of dynamite fishing and other causes of stranding.

The team suggested improving the response capability of communities and groups and opening facilities to support the rehabilitation of stranded marine animals. To date, Ocean Adventure is said to be the only place capable of doing that.