SINGAPORE – Giant clams are reef builders, as well as key sources of food and shelter for reef animals. Even their faeces have been found to be highly nutritious for fish. Some giant clams can live beyond 100 years.
But there are fewer and fewer of them in South-east Asia, which is home to eight out of the world’s 12 giant clam species.
Their long-term existence hinges on strongly enforcing anti-poaching laws and improving the survival of offspring. Scientists also need sufficient funding to sustain conservation programmes, said 20 South-east Asian experts of the flamboyant bivalves.
These were the key conclusions of a policy paper published on April 6 to improve the conservation of the threatened reef animals in the region.
While international regulations and local laws prohibit the poaching of the threatened giant clams, overfishing and the illegal trade persist in the region, with some local communities also claiming them for food and ornaments.
In January, more than 150 giant clam shells, weighing around 10,000kg, were seized at the El Nido coastal municipality in the Philippines’ Palawan archipelago.
“Marine protected areas in South-east Asia can be quite big. To police and enforce the entire area can be difficult. (Rangers) could be busy at one spot, exposing the other side to poachers,” said giant clam expert Neo Mei Lin from NUS’ Tropical Marine Science Institute, who led the report, published in the scientific journal Aquatic Conservation: Marine And Freshwater Ecosystems.
The two remaining giant clam species found in Singapore – the critically endangered fluted giant clam and endangered boring giant clam – are threatened not by poaching but by the degradation of habitats and sediments on reefs due to years of coastal development.
Found mainly in the reefs of the Southern Islands, the vibrant clams are few and far between. Based on surveys over the years, there were around 100 fluted giant clams and fewer than 30 boring giant clams as at 2024. They are also widely spread across the reefs, limiting reproduction.
“The numbers are so low that they’re not able to reproduce with each other,” noted Dr Neo.
To prevent these “jades of the sea” from vanishing, scientists in the region like Dr Neo have taken to breeding and culturing giant clams in the lab, before restocking them in reefs.
However, most restocking projects in South-east Asia have shown mixed results, stated the paper, citing challenges like low juvenile survival rates, high mortalities of restocked clams, poaching and high costs of production.
