By Carmencita A. Carillo

ISLAND GARDEN City of Samal — It starts out looking like a normal five-pointed star, but the crown-of-thorns starfish (Acanthaster planci) eventually develops more arms, swells up to one meter in diameter, grows thorns, and preys on corals.

This invertebrate — as it is in other areas in the Indo-Pacific including the Great Barrier Reef Marine Park — is threatening the coral reefs around the Island Garden City of Samal (IGaCoS), a popular tourist destination in Mindanao for its beach resorts, snorkeling and diving.

To address the risk of an outbreak, the Bureau of Fisheries and Aquatic Resources (BFAR) in Davao Region is planning to reduce the number of the crown-of-thorns starfish through continued harvesting activities in partnership with local divers.

“We want to reduce the number of crown-of-thorns, especially in the popular diving sites in IGaCoS because they are destroying the corals,” BFAR Region 11 Director Fatma M. Idris said. “Samal’s diving sites are frequented by tourists so it is important to take care of them,” she said.

Last year, members of the BFAR-Region 11 and the Divers Association of Davao City collected up to 20 sacks of the starfish, a task that they said is not easy.

“We are very careful in collecting the crown-of-thorns because they are very itchy and painful once its parts get into contact with human skin,” Ms. Idris said.

“The crown-of-thorns also easily breaks and the broken parts can easily regrow and multiply… They look nice because of their colors but they are very destructive,” she pointed out.

The starfish, which come in a variety of brilliant colors, are not the only problem. Their population is increasing abnormally because their natural predators are being taken by humans, Ms. Idris said.

Among these natural predators are the Napoleon Wrasse or Humphead Wrasse (Cheilinus undulatus), one of the largest reef fish in the world that feed on urchins and crown-of-thorn starfish.

The World Wildlife Fund for Nature (WWF) reported that the Humphead Wrasse, classified by the International Union for Conservation of Nature (IUCN) as endangered, has often been the object of illegal, unregulated and unreported fishing as it is a highly valued fish in the luxury live reef fish trade, fetching a price of up to $250 to $300 per kilogram in China.

The WWF also said the illegal harvesting of the Humphead Wrasse using cyanide is still prevalent in the Philippines, Indonesia, and probably eastern Malaysia.

While the mature Humphead Wrasse are harvested for the live reef fish trade, the small juveniles are collected for the aquarium fish trade.

This fish species cannot be artificially cultured in hatcheries, and so there is no way of increasing their population in the wild.

“We tried ordering the Napoleon Wrasses in one of the Chinese restaurants here and were told to come back since they ran out of stock,” said Councilor Leonardo R. Avila III, chairman of the committee on environment. “This means there are still people who harvest the fish species even it if is already prohibited,” he added.

Another natural crown-of-thorns predator is the trumpet shell, known to locals as budyong, which is also classified as endangered.

Ms. Idris said the harvesting, consumption, and sale of trumpet shells for ornamental use has been banned in the country. Vendors, particularly at the popular souvenirs place Aldevinco Shopping Center in Davao City, have been informed of about the prohibition and airport authorities are on the lookout for smuggling of these shells, she said.

“It is important to protect the corals not only from dynamite fishing but also from the crown-of-thorns,” said Mr. Avila, “since this is where pelagic fishes lay their eggs and where the small ones take shelter.”

Mr. Avila, who is a CoastGuard Auxilliary member, also pointed out that humans also contribute to the destruction of corals through their unmanaged waste.

“It’s all about maintaining a balance in the ecosystem. There is an imbalance now,” he said.

WASHINGTON — The blue whale is the largest creature on Earth and perhaps the biggest that ever lived, so it is no surprise it has a huge appetite. But the strategies this behemoth uses to get enough food has not been well understood — until now.

Scientists said last week that a study of blue whales off California’s coast that used tags to track their movements and their prey, tiny shrimp-like crustaceans called krill, showed these marine mammals are not indiscriminate grazers as long thought.

Instead, they feed more intensely when krill density is high but avoid doing so when there is less krill in order to save oxygen for future dives.

“We found that blue whales have a complex strategy of switching from conserving oxygen when prey quality is low, to intense foraging at the expense of oxygen when prey quality is high,” said research ecologist Elliott Hazen of the US National Oceanic and Atmospheric Administration Fisheries’ Southwest Fisheries Science Center and the University of California Santa Cruz.

Blue whales are filter-feeders, using baleen plates in the mouth made of keratin, also found in people’s fingernails, to strain krill from ocean water.

When lunge-feeding, the whale accelerates and opens its mouth, taking in a volume of prey-laden water up to 130% of its weight. Its throat distends, filling with water, and then it uses throat muscles and its tongue to force water out of its mouth through baleen plates that act as a sieve to keep the krill.

Blue whales eat up to around four tons of krill daily.

“The whales are much more actively assessing their environment and taking advantage of prey in ways that were unknown before, to maximize energy gain,” added ecologist Ari Friedlaender of Oregon State University’s Marine Mammal Institute.

The study included information from more than 50 whales, using tags applied via suction cups and data on prey.

Blue whales, found in all the world’s oceans, are listed as endangered thanks to 20th century whaling that drove them nearly to extinction.

There are about 10,000 worldwide. They reach up to about 98 feet (30 meters) long and 180 tons.

“Blue whales face a gauntlet of risks in the ocean from ship-strikes to human noise, and for an animal living on the knife-edge these dense patches of prey are critical to put on mass and ultimately reproduce,” Hazen said.
The research appears in the journal Science Advances. — Reuters