Shijimi Freshwater Clam

Shijimi Freshwater Clam

Shijimi is a type of freshwater clam that is a common ingredient in Japanese household cooking widely available in grocery stores and seafood shops. Shijimi is known to have high levels of ornithine, a substance effective in relieving fatigue and hangover.

In Aomori, shijimi can be found in Lake Jusanko, located in the northwest of the Tsugaru peninsula near the Sea of Japan, and Lake Ogawara near the Pacific ocean. Both lakes are brackish lakes where salinity is lower as sea water mixes with fresh water. These are ideal conditions in which shijimi can thrive.
In addition, both lakes benefit from natural mineral water from the Shirakami Mountains and Hakkoda Mountains, respectively. “Lake Jusanko Yamato Shijimi” was registered in the geographical indication (GI) protection system in December, 2016, and “Lake Ogawara Yamato Shijimi” in December, 2017.
Shijimi contains high levels of succinic acid, an umami substance. To release the umami, it is recommended to freeze the clams once after purging the sand from their stomachs. Shijimi also has high levels of vitamin A and B12. In order to fully enjoy the nutritional benefits, shijimi is best eaten cooked in miso soup or ushio-jiru.

shijimi miso soup
Shijimi Freshwater Clam

Distribution Season

in season distribution period

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Lake Jusanko Yamato Shijimi

Lake Jusanko Yamato Shijimi

Lake Jusanko is situated in the northwest of the Tsugaru peninsula of Aomori prefecture. The Iwaki River flows into Lake Jusanko, which in turn drains into the Sea of Japan. The third largest lake in Aomori, it is a brackish lake where freshwater converges with ocean water.
Yamato Shijimi, or freshwater clam, thrive in Lake Jusanko as the salinity levels and the dissolved oxygen content in the lake create ideal living conditions. The “Lake Jusanko Yamato Shijimi” is highly valued for its taste and umami flavor in broth.
The best season for shijimi is between July and August, when they reach their spawning period. They are largest and most flavorful during the peak season. Winter shijimi caught between the months of December and March are also popular as “Kan-shijimi,” filled with flavor and tender flesh.

Traditional methods developed by local fishermen are used for shijimi fishing, such as “joren” and “kara-otoshi.” “Joren” refers to the method of catching the clams by scooping them from the sand and mud on the bottom of the lake. “Kara-otoshi” drops any clam that is not sufficiently large, which ensures sustainability. In addition, various sustainable practices are in place, such as catch quotas, setting up fishing seasons and protected areas, breeding practices, protection of larvae, and protection of the natural environment such as lake bed clean-up and afforestation. The sustainable fishing practices including the unique traditional fishing methods were recognized by the Ministry of Agriculture, Forestry and Fisheries and “Lake Jusanko Yamato Shijimi” was registered under the Geographical Indication protection system (GI).
The shijimi clams from Lake Jusanko are known for their flavorful and mineral-rich broth, thanks to the body of water, rich in nutrients and the surrounding natural environment.

A local specialty “Lake Jusanko Shijimi Ramen” uses the Lake Jusanko Yamato Shijmi and is available in restaurants around Lake Jusanko.

Harvest Months (Lake Jusanko Yamato Shijimi)

in season distribution period

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Lake Ogawara Brackish Water Clam

Lake Ogawara Brackish Water Clam

Lake Ogawara in Aomori prefecture is the largest brackish water lake in the Tohoku region where freshwater and ocean water from the Pacific converge.

Lake Ogawara is one of the largest sources of brackish water clam, or Yamato-Shijimi, in Japan. Engine-powered boats with dredging equipment are not used in Lake Ogawara for shijimi fishing, which minimizes damage to the clams. This allows for clams to maintain an excellent undamaged appearance and stay fresh longer. Additionally, the Yamato-shijimi in Lake Ogawara are caught only after being raised for four years. This contributes to their larger than average sizes with a diameter of 15 mm or longer. Lake Ogawara has a specialized fish market solely for brackish water clams (Lake Ogawara Regional Wholesale Fish Market). The established centralized system ensures that every clam fished from Lake Ogawara goes through a single distribution point, and the clams are all of consistent quality.

In December 2017, recognized for the exceptional condition as a fishing ground, the comprehensive system for sustainable fishing, and the distribution system, Lake Ogawara Brackish Water Clam was registered under the Geographical Indication protection system (GI) of the Ministry of Agriculture, Forestry and Fisheries.
The clam is a highly versatile ingredient that has substantial flesh and makes wonderful rich dashi broth. Available year-round, Lake Ogawara Brackish Water Clams are highly sought out in the market.

Harvest Months (Lake Ogawara Brackish Water Clam)

in season distribution period

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

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