KUCHING: The semah, commonly found in Sarawak, is thriving in the headwaters of the Baleh River deep in the Heart of Borneo, according to researchers.
The yellowish-gold fish has been found to dominate the Upper Baleh River, more than other freshwater fish species from the loach family.
Universiti Malaysia Sarawak (Unimas) researcher Nur Ezaimah Idris said semah dominates most of the riverine system in upper Baleh, followed by lelekat, which is also known as the Bornean sucker fish.
“Semah is more easily found in Kian River, a tributary to Baleh River, compared to other tributaries,” she said at a recent Heart of Borneo seminar on a scientific expedition to Upper Baleh.
In her presentation on “Fish Fauna of Tributaries of Upper Baleh River, Kapit, Sarawak,” she said semah (Tor douronensis) accounted for 27.4% of fish individuals sampled, out of 15 species recorded in the study area.
Bekut (Parhomaloptera microstoma) accounted for 18.4% and lelekat (Neogastromyzon chini) 10.4% of the sample size.
Ezaimah was one of 17 researchers from different disciplines who took part in the first scientific expedition to the proposed Upper Baleh National Park in November 2015 and presented their findings at the seminar here a year later.
The expedition was conducted by the state Forest Department, Sarawak Energy Bhd, Unimas and WWF-Malaysia.
The findings will be documented in a book titled Conserving the Gems of Upper Baleh.
WWF-Malaysia freshwater management and conservation officer Mohd Khairulazman Sulaiman, who studied the genetic diversity of semah in the area, found that the fish has a unique genetic trait variation.
“Genetic variation is important for species survival as it enables species to react and adapt to any changes in the environment,” he said.
He also noticed that the upper Baleh has a high level of dissolved oxygen, which is important for the growth of semah.
“Semah, especially in their juvenile period, need at least seven to eight milligrams per litre of dissolved oxygen for their metabolic activity,” he added.
Both researchers agreed that semah is abundant in the Kian River compared to other rivers.
The semah documented in the river were also one of the most genetically diverse compared with those in other tributaries surveyed, such as the Ukit, Irak, Penganen, Selentang, Jambu, Tor and Entakun rivers.
The Kian River is situated south of the Upper Baleh River and is one of the tributaries with the highest fish species found during the expedition.