Abashirikosan Shijimigai

The Abashirikosan Shijimigai is a large-sized Yamato shijimi (brackish water clam, Corbicula japonica) ⁽¹⁾ that is typically grown for about or more than seven years in the cool climate of Abashiri, Hokkaido prefecture.
　Abashiri is well known in Japan as a pioneer of brackish water clam production in Hokkaido, and Abashirikosan Shijimigai is highly rated by wholesalers as a popular ingredient that has excellent color, glistening visual appeal, and texture. The clams are traded at a price that is about 1.5 times higher than the national average for brackish water clams.

The Yamato shijimi that live in Lake Abashiri and in part of the Abashiri River in Hokkaido Prefecture are known as Abashirikosan Shijimigai.
　The clams are caught by dredging the bottom of the bodies of water with a hydraulic jet scoop called a "joren" in Japanese. The harvested brackish water clams are machine-sorted on the boat according to shell length, while additional visual inspection is used to remove small stones and brackish water clams with damaged shells. Once unloaded from the boat, the clams go through another round of sorting for any empty shells and further quality control.
　The shipping standard specifies a shell length (the widest part of the shell) of 14 mm or more and the total allowable catch should be within the range announced by the Nishi-Abashiri Fisheries Cooperative.

Lake Abashiri is a brackish water lake that is fed by the Mt. Ahorodake-originating Abashiri River, which flows through mountains and plains and eventually joins the Bihoro River. The lake is Hokkaido's largest freshwater clam production area, representing more than 90 percent of Hokkaido's catch in recent years.
　In 1972, cooperative sales started and an Abashirikosan Shijimigai distribution system was established. Starting in 1985, research institutes and administrative bodies have conducted surveys on the quantity of brackish water clams and their corresponding development status. The Nishi-Abashiri Fisheries Cooperative utilizes the survey results to develop an annual production plan. Furthermore, by complying with the annual and daily allowable catch standards, an annual catch of around 800 tons has been consistent.
　In 1994, to further increase quality and improve resource management, a size restriction was established with the aim of harvesting only large brackish water clams.
　As of 2019, there are 38 Abashirikosan Shijimigai clammers and the annual catch is about 606 tons.

1. Yamato shijimi: Yamato shijimi is a species of edible bivalve that thrives in brackish waters and is endemic to Japan.