• Society

Giant salmon carp: Symbolic Mekong endemic fish species rediscovered in Cambodia

• By Chhut Chheana / USAID Wonders for the Mekong
• July 17, 2022 3:30 PM

PHNOM PENH - -  For the last few decades, people in Cambodia have been unable to catch the elusive giant salmon carp (Aaptosyax grypus). In fact, most people thought that the species had completely disappeared from the Mekong region, especially in the Mekong River in Cambodia. However, on June 28, 2022, a six-kilogram giant salmon carp, with a standard body length of 74cm and a total body length of 88cm, was caught by a fisherman in the upper part of the Seasan 2 hydropower reservoir.

The giant salmon​ carp (Aaptosyax grypus) is a unique fish species that lives primarily in deep pools in the Mekong River in central Thailand and Laos. In Cambodia, the giant salmon​ carp, known in Khmer as “Trey Pasanak”, lives in the upper part of the Mekong River in Kratie and Stung Treng provinces.

Trey Pasanak mouth’s shaped. Photo: Chhut Chheana / Wonders of the Mekong

“Pasanak” is a word derived from the Thai and Lao languages but is known in Khmer as "Trey Pasanak". Dr. Chaiwut Grudpan, from the Department of Fisheries of Obun Ratchathani University, Thailand, specializes in identifying fish in the Mekong region. He shared that the word "sanak" in Thai means "Areca palm cracker", which is a cutting tool that is usually used by people who like to eat betel leaf and the areca palm nut. The words “Pla” or “Pa" in Thai and Lao mean "fish". Dr Chaiwut Grudpan said that the fish got its name, "because the fish’s mouth is shaped like an areca palm fruit cracker.” He added that this is why “Thai and Lao people call the fish “Pasanak”, or “Areca palm cracker tool”, and in Khmer people call it “Trey Pasanak”.”

Dr. Chaiwut Grudpan considers the Trey Pasanak to be a symbol of the Mekong region and expressed his surprise at the presence of the Pasanak fish in the reservoir. He said, "the Trey Pasanak is a rare and endangered fish species that is under-researched and its numbers are poorly recorded because it is not a target fish for fishermen. Its presence is surprising and very interesting to me.” Dr. Chaiwut added.

According to Dr. Chaiwut Grudpan, he used to accompany with the retried Professor Yoshio Tomoda, from Japan to do the survey on the Aaptosyax grypus with Local Communities in Ubon Ratchathani, Thailand including Champasak, Lao PDR between 2008-2009. He said that the Trey Pasanak migrates into deep pools in the Mekong River during the winter while the weather is cold and windy. As they migrate into deep pools, the Trey Pasanak will often jump high out of the water. Dr. Chaiwut speculates, “it seems as if the species wants to show the fishermen that they are present and encourage them to come to the river and fish for them. He adds, “In Thailand, fishermen call Trey Pasanak’s stupid fish because of this behavior.”

Trey Pasanak mouth’s shaped. Photo: Chhut Chheana / Wonders of the Mekong

Mr. Chan Sokheng is the Deputy Director of the Fisheries Technology Research Office of the Inland Fisheries Research and Development Institute of the Fisheries Administration. He is also the author of the book "Freshwater Fish in the Kingdom of Cambodia (Characteristics and Brief Biology)" which contains information on a total of 388 species of fish, including brackish water fish species. Mr. Chan Sokheng has been tracking the Trey Pasanak in Cambodia for 30 years.

Mr. Chan Sokheng was the one who was informed of this exciting catch of the Trey Pasanak. After hearing the news, he immediately arranged for the transport of the fish from Stung Treng province to the Inland Fisheries Research and Development Institute of the Fisheries Administration and cooperated with the Wonders of Mekong Project in order to preserve the fish and keep it in the laboratory. Mr. Chan Sokheng describes his excitement about the catch: “I have been tracking the Trey Pasanak for a long time. I have been working in the Mekong region for almost 30 years. I go back and forward to work in the upper part of the Cambodian Mekong. This is the second time I have seen a Pasanak.” Mr. Chan Sokheng adds "the first time fishermen caught the fish on October 11, 2020, and the fish weighed 20 kg. The fish was caught in the reservoir of the Lower Sesan 2 dam.”

20 kilograms of Trey Pasanak were caught by fishermen on October 11, 2020, in the reservoir of the Lower Sesan 2 Dam. Photo: Chan Sokheng / Fisheries Administration

Mr. Chan Sokheng said that before the construction of the dam, he used to go to work on the Srepok River. “Fishermen have told me that they used to catch Pasanak in the canyons in the Srepok River. Therefore, I concluded that the Trey Pasanak must have lived in the deep pools in the Srepok River. After the construction of the dam, all the fish were trapped behind the dam," said Mr. Chan Sokheng.

Assuming that some Trey Pasanak are still present, Mr. Chan Soheng wants to collaborate with the Wonders of the Mekong project to conduct research in the area in order to conserve this important fish habitat. "I look forward to working with the Wonders of the Mekong project to conduct research that informs effective conservation of this endangered species," said Mr. Sokheng.