Sea sentinels

Vulnerable to collisions

With a very limited lung capacity, these gentle giants typically spend no longer than three minutes under water. This makes them vulnerable to collisions with vessels and the accidental consumption of floating marine debris when they surface to breathe.

Marine litter, including plastic packaging and ropes, as well as discarded or lost fishing gear such as nets, lines and traps, can cause significant harm to sea animals.

Ingesting marine debris may lead to gastrointestinal tract damage, while animals that get entangled in plastic pollution may get injured and starve to death — or be left at the mercy of predators. Animals like dolphins, whales and porpoises that need to regularly surface for air may drown due to entanglement.

Dolphins, whales, sharks, turtles and other species have also inadvertently gotten caught during commercial fishing operations such as trawling and drift netting. Entrapment in nets and lines, and accidental capture, can result in injury and death of the bycatch.

According to the Food and Agriculture Organization of the United Nations, it is estimated more than 500,000 marine mammals are incidentally captured each year on a global scale.

Ship strikes pose a major threat to marine life as well, with a global average of 30 whales, dolphins and porpoises getting killed each year after being hit by ships.

The risk of ship strikes is high in the waters around Singapore, including the Strait of Malacca, which are some of the busiest in the world, Chua said. He said this risk can be mitigated with the enforcement of vessel speed limits in whale collision hot spots.

Maritime traffic also contributes to underwater noise pollution.

Sound travels much faster and further underwater than in air. With most marine animals relying on sound for communication, and feeding and navigation, loud noises from shipping, military sonar, industrial activities or underwater explosions distress and disorientate them.

Underwater noise pollution can also cause hearing loss in marine mammals and alter their acoustic behavior, but is currently not legally recognized as an official threat to marine life in Southeast Asia, Ponnampalam said.

Coastal development, including land reclamation and dredging, has also been proving to be an increasing threat to marine life, as it can fragment marine mammals' habitats, into smaller, isolated areas.

"There is so much research that could and should be done, if only we, the community of Southeast Asian researchers, had more resources to do so," said Ponnampalam.

Potential areas of research include bioacoustic research to investigate how underwater noise pollution impacts marine mammals, genetic research to identify movement patterns and the genetic diversity of marine mammal populations in the region, as well as how resilient they are to disturbances.

She added that it is also important to learn about sociocultural interactions and the value of marine mammals in Southeast Asia within local communities and conduct ecological research to learn more about marine mammals' distribution, population abundance, habitat use and behavior.

The Straits Times, Singapore