【Reading】ありあけかい

【English Name】Ariake Sea

A bay in the northwestern part of Kyushu, surrounded by the four prefectures of Fukuoka, Saga, Nagasaki, and Kumamoto, it is a closed sea area with limited water exchange with the open ocean. Its total area reaches roughly 1,700 km², boasting the largest scale among all the bays of Kyushu.

A striking feature of this sea area is the magnitude of its tidal range, said to be the greatest in Japan. At the Oura district in the innermost part of the bay (Tara Town, Saga Prefecture), the average tidal range at spring tide records about 4.9m, and this intense tidal variation is thought to be the driving force that nurtured Japan's largest-scale tidal flats. In a survey conducted by the Environment Agency in 1994, the tidal-flat area was recorded as about 20,712 hectares, revealing the fact that roughly 40 percent of the nation's total tidal-flat area is concentrated in this region.

Owing to its structure, into which numerous rivers including the Chikugo River flow, the salinity varies greatly by season, forming a distinctive water quality with high turbidity. As a result of these environmental conditions overlapping in complex ways, a peculiar ecosystem became established here. Rare fish and shellfish called continental relict species—such as mutsugoro (mudskipper), warasubo, etsu (Japanese grenadier anchovy), tairagi, and agemaki (jackknife clam)—are their representatives. They are a group of organisms that strongly retain the vestiges of an era when the area was once connected by land to the tidal flats of the Asian continental coast, and many are limited in their domestic distribution to the area around the Ariake Sea.

Its connection to sushi is also deep, as it is an indispensable presence as a major production area for konoshiro (dotted gizzard shad), kuruma-ebi (kuruma prawn), gazami (swimming crab / watari-gani), and asakusa-nori, the raw material for nori. This region, where distinctive fishing methods and local food culture have taken root, continues to support sushi culture from the ground up as a supplier of abundant marine resources.