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Giant salmon carp rediscovered after gap of 20 years

Posted: Wednesday 6 July, 2022 @ 08:55:43

Aaptosyax grypus is a spectacular silvery salmon-sized predatory cyprinid which is presumed to use its eyesight to catch smaller cyprinids and other fish. Formerly it was found in the Mekong River in Laos, NE Thailand and Cambodia.

In February 1997, Voluntary Services Overseas (VSO) volunteer Peter Cunningham, currently WRFT Biologist, photographed an adult female Aaptosyax grypus (Rainboth, 1991) in the fish market in Pakse in southern Laos. His picture currently appears on the Wikipedia entry for this species Further background and a higher resolution picture of Aaptosyax grypus can be found here.

During his VSO posting, working with the Lao Community Fisheries and Dolphin Protection Project based in a small fishing village on the banks of the Mekong River in Muang Khong, Peter became familiar with many species of Mekong fish and the traditional fisheries and provided support for the establishment of village based fish conservation zones within the Siphandone area of Southern Laos. Two other adult Aaptosyax grypus were recorded in the Pakse fish market in 1997 and a juvenile was caught in a gill net near Khone Island.

Since returning to Scotland in 1998, despite regular checks on the internet, no further records or photos of Aaptosyax grypus had been found. As elsewhere in the world, Mekong fishes have been under pressure from environmental damage associated with human activities including overfishing and dam building. In 2016 National Geographic ‘megafish’ biologist, Zeb Hogan, who conducted his PhD studies on Mekong catfish in the 1990s, was unable to confirm the continued survival of Aaptosyax grypus. .

However, on 2nd July 2022, a team of scientists were stunned when an Aaptosyax grypus – previously considered extinct in Cambodian waters – was caught by a fisherman near the Sesan II hydropower dam in Stung Treng province.

Thach Panara, head of the Laboratory, Inland Fisheries Research and Development Institute under the Fisheries Administration, Cambodia, told The Phnom Phen Post that no examples of the Mekong giant salmon carp (Aaptosyax grypus) had been found in the Kingdom’s waterways in more than two decades. The administration’s fisheries resource team had supposed the fish extinct. The July 2 catch caught the team by surprise.

He said: “1999 was the last recorded sighting of the giant salmon carp in Cambodia. We did not expect to see their return.”

The full story can be found here .

So what’s this got to do with Wester Ross?

It is too easy just to focus on parochial biodiversity challenges including those faced by populations of wild Atlantic salmon in many of the rivers in the NW of Scotland. We share a responsibility for conservation of global freshwater fish biodiversity. Our investments and commerce can fuel environmental degradation.

Aaptosyax grypus is threatened by dam building programmes which block migration routes and flood spawning areas, by deforestation and degradation of water quality, as well as over fishing, perhaps especially with gill nets.

The rediscovery of Aaptosyax provides a glimmer of hope.


How many other Aaptosyax grypus survive? Can this spectacular fish species be saved?