From Wee Beng Wah
Writter: Sulok Tawie
KUCHING: Marine mammals, especially dolphins, face fresh threats off Sabah and Sarawak.
They are now threatened by the loss or degradation of their habitats, particularly mangrove forests, coral reefs and seagrass beds.
Dr Saifullah Ariffin Jaaman, a lecturer on marine mammal and fishery sciences with Universiti Malaysia Sabah, said the threats were discovered during surveys conducted on marine mammals in the two states by scientists and researchers.
"Many jungles, especially upstream of rivers in the two states, have been logged. The land is being cultivated now or turned into large-scale oil palm plantations."
Saifullah said this in a paper presented at a recent Conference of the European Ce-tacean Society.
He said that these areas contained many drifting logs and debris, especially during the northeast monsoon.
"In some areas left cleared, rain pushes sediments into the rivers and bays. This increases the turbidity of the water, thereby decreasing water quality."
Waste, especially plastic bags, from urban and industrial areas, are also a common sight in rivers near coastal towns.
Aquaculture farms have resulted in the loss of large areas of mangrove along the eastern coast of Sabah. Much of it has also been chopped for wood chips or firewood.
"Their disappearance has led to sediment erosion, water pollution and loss of nursery habitats for young fish."
This affected reefs and seagrass, Saifullah said.
The decline in fish resources in the region can be attributed to the destruction of fish habitats, deployment of destructive fishing methods and over-fishing, he added.
Saifullah said the rapid development of Sandakan and Tawau in Sabah and Tanjung Manis and Muara Tebas in Sarawak into major ports and industrialised towns might affect the natural habitats and behaviour of the populations of Irrawaddy dolphins there.
In addition, a causeway running across Sungai Santubong (in Sarawak) which completely cuts flow to the ocean and a barrage in Pending near here that limits the flow of Sungai Sarawak to the ocean (through Muara Tebas) pose problems to the natural migration routes of inshore cetaceans in and out of the Sungai Sarawak.
Intensive petroleum exploration activities in waters off Miri, Bintulu and Brunei might also affect fish and marine mammals, said Saifullah.
Although large whales such as the sperm whale and the false killer whales were known to prefer areas near the continental slope or in the deep-ocean waters, he said, aerial sightings showed they were in shallow coastal waters.
"The whales probably venture into the area occasionally in search of food," he said, adding other marine mammal scientists had recorded sightings of sperm, fin and false killer whales in waters over 1,500 metres deep off Sabah’s coast.