Manila Clams Origin Explained: Are They From the Philippines as They Spread Along the Atlantic Coast?

The discovery of Manila clams along the northwestern Atlantic coastline has prompted fresh questions about one of the world's most valuable shellfish. While the species supports a global seafood industry worth around $7 billion (£5.2 billion) a year, scientists are now tracking its emergence as a new invasive species in New England.

The finding has also revived a common question among the public: despite their name, are Manila clams actually from the Philippines? As researchers investigate how the shellfish reached the region, they are also working to determine what its arrival could mean for native marine ecosystems.

Where Do Manila Clams Originate?

Despite their name, Manila clams are not native to the Philippines. According to researchers, the species, Ruditapes philippinarum, originates from the coastal waters stretching from Russia's Sakhalin Islands through Japan to southern China.

The common name has often led to confusion about the clams' origin, with many assuming they first came from the Philippines. However, scientists say the shellfish's natural range lies elsewhere in East Asia and that it spread internationally through human activity.

Since at least the early 20th century, Manila clams have expanded across coastlines throughout much of the Northern Hemisphere. Until recently, however, the northwestern Atlantic coastline remained the last region where established populations had not been recorded.

Manila Clams Spreading Along the Atlantic Coastline

A study published in the journal Biological Invasions has confirmed that Manila clams have now established populations around Cape Cod and the Boston area. The research was led by scientists from the University of Massachusetts Amherst, MIT Sea Grant at the Massachusetts Institute of Technology, and the Center for Coastal Studies.

The discovery offers researchers a rare opportunity to monitor an invasive species during the early stages of its spread into a previously unaffected ecosystem.

'Given that Manila clams are everywhere else in the Northern Hemisphere, it was only a matter of time before they showed up here, and we've been keeping an eye out for them,' said marine scientist Aly Putnam, a postdoctoral researcher at UMass Amherst and lecturer at Smith College, who served as the study's lead author.

Researchers said it remains unclear how the species arrived in northwestern Atlantic waters, making its introduction another key focus of ongoing research.

Why Scientists Are Concerned About the Invasive Species

Although Manila clams are highly prized in global seafood markets, scientists say their spread could present challenges for native shellfish populations and coastal habitats.

The study notes that Manila clams can compete with native shellfish for food and habitat while also hybridising with related species. Where large colonies become established, they may alter surrounding ecological communities and affect marine biodiversity.

Researchers have not yet determined the long-term consequences of the species' arrival in New England. Understanding whether the shellfish will remain relatively limited or continue expanding will be an important part of future monitoring.

Researchers Assess Possible Ecological Impact

Scientists caution that the arrival of Manila clams may not be entirely negative. Carolina Bastidas, co-investigator and research scientist with MIT Sea Grant, said the shellfish could also provide an additional food source for predators, potentially reducing pressure on some native species.

'We do need more research to understand the Manila clam's potential effects on the shellfishing industry and ecological communities,' Bastidas said. 'On the positive side, because Manila clams can become a source of food for other animals, they can relieve pressure on native species. For example, the predatory pressure of green crabs on softshell clams. So, there could also be positive impacts.'

Researchers are now studying how widely Manila clams are spreading along the Atlantic coastline, whether their populations continue to grow and how they interact with other marine species. Putnam said the discovery marks only the beginning of understanding whether the shellfish will become a minor addition to New England's coastal ecosystem or a more influential species in the years ahead.