January 06, 2026 Corporate Citizenship

IHI participated in building a fishway for Biwa trout in Higashiomi City, Shiga Prefecture

The IHI Group participated in the construction of a fishway for Biwa trout on October 18 and 19, 2025, at the Shibu River, a tributary of the Echi River in Higashiomi City, Shiga Prefecture.
The Lake Biwa trout is an endemic species found only in Lake Biwa, spending most of its life within the lake. Like salmon, it migrates upstream to rivers during the spawning season and ends its life after spawning.
The Echi River, flowing through Higashiomi City, is known as a precious waterway where Lake Biwa trout still migrate upstream to spawn, with their habitat preserved from the lake’s mouth up to about 30 km upstream. However, a sand control dam located approximately 500 meters upstream from the confluence of the Echi and Shibu Rivers prevented the trout from migrating further upstream, leaving them unable to secure sufficient spawning grounds. Therefore, starting in 2021, the Echi River Fisheries Cooperative Association took the lead in collaborating with local stakeholders to install a simple fishway at this dam. Experts have confirmed that this simple fishway has extended the spawning zone approximately 1.1 km further upstream.
The IHI Group was invited to participate in this activity by the Echi River Fisheries Cooperative Association because it operates an IHI Infrastructure Systems (IIS) factory in Higashiomi City and collaborates with the city on “Nationally Certified Sustainably Managed Natural Sites”* initiatives. A total of 15 personnel from IHI and IIS participated over two days in constructing this fishway.

• * Areas certified by the Ministry of the Environment as “areas where biodiversity conservation is being achieved through private initiatives and other efforts.”

On the first day, October 18, approximately 50 participants, including administrative officials from the Ministry of Agriculture, Forestry and Fisheries, Shiga Prefecture, and Higashiomi City; private companies, including the IHI Group; experts; and university students gathered. Work commenced at 10:00 AM. Under the direction of Mr. Murayama, Chairman of the Echi River Fisheries Cooperative Association, the morning was spent assembling the upper section’s framework using single-pipe tubes. In the afternoon, corrugated pipes forming the fishway were installed atop the framework, concluding the first day’s work. In the evening, a social gathering provided an opportunity to deepen friendships with local residents.

On the second day, October 19, approximately 50 participants gathered. In the morning, they assembled the lower section’s framework and installed corrugated pipes. Once the waterway was connected from upstream to downstream, they conducted a test run to identify leaks and implement leak prevention measures. In the afternoon, they installed nets to prevent Biwa trout from falling, completing the fishway.

Over the course of two days, a total of 100 people participated in constructing the Biwa trout fishway, reaffirming how deeply the local community cherishes both the Biwa trout and their immediate natural environment.
This year saw less rainfall than usual, raising concerns about whether the Biwa trout would be able to migrate upstream. However, rainfall on October 31 allowed the Biwa trout to safely reach the Shibu River, and it was confirmed that they ascended the fishway.

The IHI Group will continue its nature restoration efforts in Higashiomi City and further advance business activities that take greater consideration of biodiversity.

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