Run-up of Sweetfish in Tama River Reaches Record High of 1.96 Million

Copyright Ministry of Land, Infrastructure and Transport. Keihin Office of River

A sweetfish migration survey of the Tama River, Japan, estimated that 1.96 million fish ran upriver, which marked a record high since the survey started in 2006. It was conducted at Chofu Diversion Weir of the Tama River, and was released on August 23, 2010 by the Keihin Office of River, Kanto Regional Development Bureau, Ministry of Land, Infrastructure and Transport.

The Tama River, officially classified as a Class 1 river, runs through the metropolitan area. This annual survey for the river was conducted in Ohta Ward, Tokyo from March 23 through June 13, 2010. In previous surveys, an estimated 900,000 sweetfish ran up the river in 2006, and the figure increased to about 1.4 million in 2007. However, the number fell to about 800,000 and 470,000 in 2008 and 2009, respectively.

Water quality of the Tama River has improved according to the biochemical oxygen demand (BOD), which a means to quantify water pollution. The BOD has been within the environmental limit at all observation points in the river since 2007.

Posted: 2011/01/03 06:00:15 AM