A great cormorant tucks in to an upstream migrating sweetfish at the Tama River's Chofu Intake Weir in Kawasaki, Kanagawa Prefecture, in this recent photo. Straddling the border between Tokyo and Kanagawa Prefecture, the Tama River is currently host to young sweetfish, known as "chi-ayu" in Japanese, swimming upstream. The fish, measuring about 5 centimeters, were seen leaping above the current to their destination before the cormorant gobbled them up.
According to the Tokyo metropolitan islands area research and development center of agriculture, forestry and fisheries, 2018 saw the second largest recorded number of upstream swimming sweetfish on the Tama River, with around 9.94 million. However, according to data as of May 12, 2019, the figure remains only about 10% of that from the same period last year. It is thought that a reduction in water-flow due to low rainfall is to blame, but a concrete cause has yet to be identified.
(Japanese original by Koichiro Tezuka, Photo Group)