Sites - Important Bird and Biodiversity Areas (IBAs)
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144o 24.00' East 43o 56.00' North
A1, A3, A4i
0 - 5m
Year of IBA assessment
Wild Bird Society of Japan
Site description Lake Tohutsuko lies between Abashiri City and Koshimizu Town in eastern Hokkaido. The narrow strip of sand dune (Koshimizu Gensei Kaen) separates Tohutsuko, an inland sea-lake, from the sea. The lake has an area of 900 ha with 27.3 km of the shoreline, and an average depth of 1.1 m. The lake is relatively shallow with the deepest part being 2.5 m. Some rivers flow into the lake, and approximately 118 ha of wetlands are found around the lake. Alnus japonice forest is around the rivers, and the marsh is dominated mainly by Carex and Phragmites australis, and few Typha latifolia and Scirpus tabernaemontani. In the brackish water, a salt marsh exists with Salicornia europaea and Triglochin maritima.. Cattle have been grazing selectively, so communities of Iris setosa, Rose rugosa and Themopsis lupinoides are found in patches.