Ramsar Sites Shinji-ko and Nakaumi


[ Nymphoides Indica ,Shinji-ko,Nakaumi and Stylurus Nagoyanus ]

Principal Features

Location[Shinji-koandNakaumi] The Chugoku Region is a wide area extending westward from Osaka in Honshu, the largest island of the Japanese archipelago. It is further divided into the northern Sanin Region and southern Sanyo Region by the Chugoku mountain ranges that run horizontally from east to west. While the Sanyo Region has relatively mild weather, the Sanin Region has a severely cold climate with frequent snow in the winter.

 The two brackish water lakes of Shinji-ko and Nakaumi are located at the Shimane and Tottori prefectural border in the central part of the Sanin Region. These lakes are linked by the Ohashi River, which extends 7km into the estuary of the Hii River, originating in the Chugoku mountain range. The upstream lake, Shinji-ko, covers approximately 7,910ha and is the 7 th largest lake in Japan, with an average depth of 4.5m and a salinity level of only 1/10 seawater. The downstream lake, Nakaumi, covers approximately 8,620ha and is the 5 th largest lake in Japan, with an average depth of 5.4m and a salinity level that reaches as much as 1/2 seawater.

      Although they both belong to the same river system, each lake has very different characteristics with its own unique biodiversity.




Shinji-ko offers an essential habitat for approximately 80 brackish water species of fish and shellfish, including Shinji-ko Goby discovered first in Shinji-ko, as well as . A special feature of this lake is the annual catch of Corbicula Clam (about 7,000 tons), which at 40% of the national total, is the largest catch in Japan. Shinji-ko is also home to numerous migratory birds. 240 species have been recorded here. To be specific, more than 20,000 Tufted Ducks and 5,000 Scaups are sighted each year among over 40,000 wild ducks and geese. Shinji-ko also supports more than 1% of the world's White-fronted Geese, Tufted Duck and Scaup population.

      In Nakaumi, 260 species of wild birds have been observed, making it one of largest wintering spots for ducks and geese, hosting more than 75,000 birds every year. In particular, Nakaumi supports more than 1% of the East Asian population of Tundra Swans, Common Pochards, Tufted Ducks and Scaups. Furthermore, it serves as the crucial southernmost wintering spot for Tundra Swans.


[Tufted Duck,Scaups,White-fronted Geese,Tundra Swans and Common Pochards]




Since 1963, Shinji-ko and Nakaumi had faced the reclamation and desalination projects that aimed to form new agricultural farmlands. However, the national policy of cutting back on the acreage under cultivation and locals' active movement against the development plan stopped the reclamation project in 2000 and the desalination project in 2002. Subsequently, both lakes have now been designated as Ramsar sites - 8 November 2005 (COP9).


Wise Use of Shinji-ko and Nakaumi


The Ramsar Convention strives not only to conserve wetlands, but to also promote their wise use. Hence, the term ‘wise use' is emphasized by the Ramsar Convention. Efforts are now being made to ensure that Shinji-ko and Nakaumi are used wisely.

      In particular, the fishery of Corbicula Clams in Shinji-ko may be considered a good example of ‘wise use'. Since days gone by, the fishermen of Shinji-ko have always agreed with each other on the amount of clams taken (150kg a day) and fishing time (four days a week, four hours a day) to prevent over-catching, and the smallclamdredgingdevice(JOREN)hasItsbeautifulsunsetthatsetsinthelakeagainstthebackdropofYomegashimaIsland.openingsbigenoughforsmallerclamstoescape.ThisishowthefishermenhereusecreativemeanssothateveryonecanenjoyShinji-ko'sclamsforalongtimetocome.




[ Japanese seaperch, Metapenaeus ensis , Eel, Japanese smelt, Salangichthys microdon, Carp   Corbicula Clam and The Seven Delicacies of Shinji-ko ]



Our Lakes Shinji-ko and Nakaumi and The Ramsar Convention


The emblem of Ramsar Sites TheemblemofRamsarSites,Shinji-koandNakaumi

In celebration of the first anniversary of their designation as Ramsar Sites, on 3 December 2006 this emblem was chosen from 651 submitted entries. The emblem symbolizes that these two lakes are working together as one towards the future. 





〒690-8501 島根県松江市殿町1番地