Nagato Suisan, Using Smolt's Heat-Resistant Salmon Fry, Completes First-Year Trial Farming; Plans Continued Collaboration Next Year to Enhance Productivity and Quality

Smolt Co., Ltd. (Headquarters: Miyazaki City, Miyazaki Prefecture; Representative Director and CEO: Ken Ueno) announces that Nagato Suisan Co., Ltd. (Nagato City, Yamaguchi Prefecture; Shigeyuki Ando) has completed a trial farming of Smolt's heat-resistant salmon (sakuramasu) developed through in-house research and development. The trial began on December 24, 2025, and concluded with the final harvest on June 8, 2026. Based on the results, both companies plan to continue their collaboration next year to improve productivity and product quality.

Overview of the Initiative

Start of Rearing

December 24, 2025

Trial Completion Date (Final Harvest)

June 8, 2026

Number of Fish Tested

Approximately 2,000 fish

Farming Method

Sea cage farming and land-based flow-through seawater systems

Farming Location

Nagato Suisan Co., Ltd. (Nagato City, Yamaguchi Prefecture) aquaculture site

Background of the Initiative

In recent years, rising sea temperatures due to global warming have made salmon aquaculture in Japan increasingly challenging. According to data from the Ministry of Agriculture, Forestry and Fisheries and the Japan Meteorological Agency, sea surface temperatures in Japanese coastal waters have risen by approximately 1°C over the past 100 years. In particular, higher summer water temperatures have increased the risk of mortality in salmon species.

Under these conditions, since its founding in 2019, Smolt has established a heat-resistant sakuramasu strain capable of growing in water temperatures around 20°C through more than six generations of selective breeding. The company has accumulated demonstration results in Kyushu, Shikoku, and Honshu.

Nagato Suisan is an aquaculture company based in Nagato City, Yamaguchi Prefecture, specializing in species such as tiger pufferfish, and is committed to revitalizing local fisheries and producing high-quality seafood. While exploring the introduction of new fish species during the winter and spring seasons, the company initiated a business collaboration with Smolt on its heat-resistant sakuramasu fry.

Features of the Trial Farming

1 Comparative Evaluation through Parallel Testing of Two Methods

This trial simultaneously implemented two farming methods: sea cage farming and land-based flow-through seawater systems. By comparing growth data, survival rates, and quality characteristics between the two methods, the project accumulated valuable insights for selecting the optimal farming method for Nagato’s environment and optimizing future production systems.

2 Use of Heat-Resistant Sakuramasu Fry

The trial used Smolt’s heat-resistant sakuramasu, developed through more than six generations of selective breeding (non-genome editing technology). This strain enables stable growth in water temperature ranges where conventional varieties struggle, demonstrating the potential to establish a new salmon production region on Japan’s Sea of Japan coast in Honshu.

3 Contribution to Year-Round Operations by Utilizing Winter and Spring

Sakuramasu are well-suited for rearing during winter and spring when water temperatures are lower, allowing farming schedules that do not overlap with peak seasons for other species in summer. This enables year-round utilization of existing aquaculture facilities and contributes to operational stability.

4 Branded Sales as "Amaou Sakura-zake"

As part of a business collaboration between Smolt and Nishitetsu (West Japan Railway Company), a portion of the sakuramasu produced in this trial farming was transferred in April to Smolt’s freshwater aquaculture facility in Ena City and is being sold under the brand name "Amaou Sakura-zake".

More details: https://prtimes.jp/main/html/rd/p/000000035.000052431.html

Future Plans

Based on the results of this trial farming, Smolt and Nagato Suisan will continue their collaboration next year to address the following challenges:

・ Optimizing feed composition and feeding programs to improve growth rates

・ Accumulating and conducting comparative analysis of survival rates and quality data from both farming methods

・ Exploring commercialization and market development for a Yamaguchi Prefecture–branded salmon

Executive Comments

Wataru Ogawa, Head of Business Strategy, Nagato Suisan Co., Ltd.

"Although sakuramasu was a new species for us to challenge, we were highly impressed by its excellent post-acclimation survival rate, fast growth, and ease of sales. We believe a key factor in our success was Smolt’s guidance on farming techniques applicable not only in sea cages but also on land. We aim to continue farming with the goal of establishing this as a new specialty product for Yamaguchi Prefecture."

Ken Ueno, Representative Director, Smolt Co., Ltd.

"Through this trial farming with Nagato Suisan, we confirmed that our heat-resistant sakuramasu fry can be successfully reared in Nagato City, Yamaguchi Prefecture—a new location for us. Conducting trials simultaneously in both sea cage and land-based flow-through systems clearly revealed the characteristics and challenges of each method, providing valuable insights for improving productivity in future operations. To accelerate the establishment of stable domestic salmon supply systems across Japan, we will continue deepening collaboration with our partners."

About Smolt's Heat-Resistant Salmon

Since its founding in 2019, Smolt has conducted sea cage farming of sakuramasu in Miyazaki Prefecture—a warm region previously considered unsuitable for salmon aquaculture. Through six generations of selective breeding, the company has established a strain capable of growing in high water temperatures around 20°C and has accumulated demonstration results in Kyushu, Shikoku, and Honshu.

Overview of Nagato Suisan Co., Ltd.

[Company Name] Nagato Suisan Co., Ltd.

[Headquarters] 2047-3, Sakizaki, Nagato City, Yamaguchi Prefecture

[Business Activities] Aquaculture

[Representative] Representative Director: Shigeyuki Ando

Overview of Smolt Co., Ltd.

[Company Name] Smolt Co., Ltd.

[Founded] April 11, 2019

[Headquarters] 1-1-1 Gakuen Kibukawa Nishi, Miyazaki City, Miyazaki Prefecture

[Business Activities] Aquaculture, aquaculture technology development, wholesale, and retail

[Representative] Representative Director and CEO: Ken Ueno