Steller's sea eagle
The mountainous area upstream extends to the Daisetsuzan National Park, while Teshiodake Prefectural Natural Park has many alpine plants. Nearer the river mouth is Rishiri-Rebun-Sarobetsu National Park, with more than a hundred species of flora including hamanasu, the Siberian lily, Japanese irises, and . Fauna of the river system include the Tōkyō lesser pigmy shrew, migratory White-tailed eagle (a Natural Monument), Steller's sea eagle (Natural Monument), Taiga bean goose (Natural Monument), and Sakhalin taimen. The and marshes are an important resting place for migratory waterfowl, and the Sarobetsu wetlands have been designated a Ramsar Site, the being a tributary of the Teshio.