What Formed the Pacific Salmon Biomass in Amur River Basin in 2000–2010s?

Abstract Excerpt:
The Amur River is the biggest salmon basin in Asia, and the tenth longest river in the world. It is 5,052 km in length, from the source of the Kerulen River (Mongolia) and further along Lake Dalainor and the Argun River. The area of Amur basin (1,855 km²) is larger than the area of the Sea of Okhotsk (1,600 km²), which the Amur River enters.