In 2022, a giant stingray (Urogymnus polylepis) was caught in the Mekong River in the northeastern part of Cambodia. The stingray measures 4 meters long from snout to tail and weighs 300 kilograms, making it the world's largest freshwater fish. Also known as whip ray, this species of stingray found in the stretch of the Mekong River spends its entire life in freshwater, unlike marine fish or other species that travel between freshwater and saltwater habitats.
Since the giant stingray was found on a full moon, Seila Chea, the project manager for the Wonders of The Mekong initiative, named it Boramy. Its discovery is considered a great way to understand the mystery of this species' behavior.
Monitoring of the Endangered Stingray
The stingray was fitted with an acoustic tag at the base of its tail before being sent back to the river. This was done to track its movements along underwater habitats such as deep pools, sandbars, and rocky outcrops. Identifying the stingray hangouts will help the experts protect the species in cooperation with the local communities and government authorities.
After a year of hydrophone tracking of Boramy, scientists gained new insights into the behavior of the giant stingray. After Boramy was released, Chea's team worked with the Joint Environmental Monitoring Programme of the Mekong River Commission in tagging almost 300 more species of fish in Cambodia and Laos.
Experts are still unsure how many giant stingrays are left. One reason little is known about them is their habit of hiding at the bottom of the river. They are not considered food, so fishermen rarely hunt them, but they usually get caught in nets.
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Role of Mekong River in Conservation Projects
The giant stingray was found in Stung Treng province, known for its diverse underwater habitats for various fish species. Aside from the freshwater stingrays, experts believe that the Mekong River is also an important refuge for other mega fish, such as the Mekong giant catfish and giant barb, which were recently classified as endangered.
The area is also vital for the food security and livelihoods of local communities in Cambodia and other neighboring countries. Since this stretch of the Mekong River supports fish spawning and migration, it has become a powerhouse of fish production, where 200 billion fish is generated annually.
Unfortunately, the river faces development threats, such as hydropower dams, which could alter the natural flow of water and worsen droughts during the dry season.
To address this concern, this area of the Mekong River has become the focus of an underwater expedition of the Cambodian Fisheries Administration in collaboration with the Inland Fisheries Research and Development Institute and other international organizations. Part of the expedition is the agreement with the local fishermen to report any catches of the endangered stingray to the project team for research study and safe release to their habitat.
In 2021, the giant stingray was listed as endangered by the IUCN Red List of Threatened Species. This is due to the declining population of freshwater stingrays from the rivers in eastern India to Borneo caused by poor habitat quality and overexploitation.
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