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Endangered mussel still harvested for food in Laos

Shell of Margaritifera laosensis specimen from the river Nam Long. Photo by Bolotov et al.

Shell of Margaritifera laosensis specimen from the river Nam Long. Photo by Bolotov et al.

Margaritifera laosensis is the only freshwater pearl mussel species known to inhabit tropical water systems, and is a traditional part of the diet of villagers in Northern Laos. However, the species is listed as Endangered by the IUCN. A study published recently in’s open-access journal Tropical Conservation Science found that the dwindling populations of the bivalve would benefit from a ban on their capture.

“We believe that the most significant threat to Indochinese pearl mussel populations comes from harvest by local people as well as from expansion of agricultural land into stream riparian zones,” the authors write.

The study also identifies threats to M. laosensis from river flow regulation, dam construction and pollution caused by deforestation.

According to Global Forest Watch, the region surrounding many of the sample sites lost 3 percent of its forest cover from 2001 through 2012. The authors write “deforestation and agriculture are leading to increased water pollution in this region,” adding that dams along the Nam Pe and Nam Long rivers cause thick layers of decomposing plant matter to accumulate and no M. laosensis mussels were found in such areas.

The region surrounding many of the team’s sampling sites lost 3 perent of its tree cover from 2001 through 2012. Forest clearing along rivers can lead to bank erosion and affect water quality. Map courtesy of Global Forest Watch. Click to enlarge.

One of the survey sites in the Nam Long River. Photo by Bolotov et al.

The research team surveyed 10 rivers, finding M. laosensis in only two, with low mussel density at each. However, the researchers also found small, young mussels at the sites, indicating the populations are reproductively viable. Previous studies reported one other reproducing population at a site in Vietnam.

“Reproductively viable populations were found only in the Nam Long and Nam Pe rivers, which are two of the only three known viable populations of this species in the world.”

According to the authors, M. laosensis is an umbrella species, in that its protection would also protect other species in its ecological community. The researchers write that protection of these pearl mussels would improve the environmental conditions of their habitat, which is limited to rivers in Northern Laos, Northwestern Vietnam, Northern Thailand and Northeastern Myanmar.

Not only may protection of M. laosensis safeguard other wildlife species in the area, but it may also benefit human communities.

“These changes will bring positive effects to local communities: more clear water for home needs, longer navigation period due to increase of high water level period, and increased fish catch,” write the authors.


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