Saving the golden mahaseer in Bhutan

As hydroelectric dams impact the migratory routes of the golden mahaseer, Bhutan looks to protect the iconic fish
<p>The golden mahaseer is one of the largest fish found in South Asia&#8217;s rivers [image by Nirmala]</p>

The golden mahaseer is one of the largest fish found in South Asia’s rivers [image by Nirmala]

The golden mahaseer (Tor Putitora) is one of the best known fish found in South Asian waters. It can grow to a length of nine feet and weigh up to a massive 40 kg, making it one of the most sought after gaming fish in the world.

At one point the range of the fish used to stretch along the whole Himalayan belt, from northern Pakistan to present day Myanmar. It was also found in the waters of Iran and Thailand. Unfortunately, a combination of environmental degradation and unrestricted fishing have had a catastrophic impact on the fish population. Today it is listed on the International Union of Conservation’s Red List of threatened species. In India, the private company, Tata Power has spearheaded a campaign to breed and release fishlings into the rivers. In Nepal, it continues to face severe challenges as laws go unenforced.

According to WWF, “The rivers of southern Bhutan are its greatest hope for survival, as long as action is taken soon to keep the threats to mahaseer at bay.” The health of the big fish is also a measure of the health of the river ecosystems of Bhutan, which impact all the flora and fauna living in and around the water bodies. For Bhutan, a Buddhist country, the golden mahaseer has religious significance as well, as the fish is one of the eight auspicious signs associated with Buddhism as practised in the Himalayan region.

The challenge of dams

The Punatsangchhu river, which runs for 320 km from its source in Bhutan to the confluence point with the Brahmaputra in India is one of the rivers where the iconic fish is found. Two major hydroelectric dam projects – Punatsangchhu I and Punatsangchhu II – are being built on the river. The electricity generated by these dams – and sold to India – is one of the main drivers of the Bhutanese economy, but it is unclear what impact they will have on the fish.

According to Singye Tshering, programme director at the National Centre for Riverine and Lake Fisheries (NCRLF), the golden mahaseer migrates all the way from rivers in India to upstream rivers in Bhutan for breeding and feeding. Tshering told that since no proper scientific study had been conducted, there is no way of knowing how the dams will affect the fish. Nevertheless, since the fish have been sighted upstream in Punatsangchhu earlier, the dams may prevent the mahaseer from migrating for spawning and feeding.

There is no official record kept of the fish in the area, but according to Kinley, who was posted by the Bhutanese government 15 years ago to keep track of the iconic fish, the number has declined ever since the commencement of the hydroelectric projects.

Mitigation measures

The government of Bhutan has started developing measures to conserve the fish. Officials from NCRLF and environment officials at the Punatsangchhu project identified a location to construct a hatchery at Harrachu, a few kilometres away from Punatsangchhu-II in November 2015. The golden mahaseer hatchery project is being built at an estimated cost of Nu 188.6 million (USD 2.8 million).

Singye Tshering told that while this may not be an ideal mitigation measure, it is recommended especially for conditions found in Bhutan, where gorges, rugged terrain and swiftly flowing rivers mean that fish passages and fish ladders will not work to offset the blockages created by dam construction. He said fish migrating upstream for breeding are collected and bred artificially in the hatchery near the dam and later released back into the river. “That way we can ensure that the fish migrating upstream for breeding are able to breed and sustain their population.”

A comprehensive management plan

The management plan includes the identification of spawning and feeding grounds and declaring them as sanctuaries, promoting and developing fish based tourism to promote a sense of ownership among the people to protect fishery resources. With WWF funding, the ministry of forest and agriculture has started a scientific remote radio telemetry study on golden mahaseer to understand its habitat. The project also hopes to establish baseline data for the mahaseer population and identify migration patterns. The study is underway in the Manas river basin covering the Mangdechhu and Dangmechhu rivers.

With these scientific findings Bhutan hopes to fight to keep the mahaseer alive and free in the Himalayan rivers, even as it continues to build hydroelectric dams that are the mainstay of its economy.