As someone who regularly investigates rivers in Japan, I often contemplate a crucial question: what kind of river should we aim for to preserve biodiversity? However, nearly all rivers in Japan have been modified for flood control and utility purposes, making it challenging to find an example of a pristine, natural river. Amidst this, I turned to Google Earth to explore rivers around the world. To my surprise, I discovered some incredibly magnificent rivers in our neighboring country, Russia. In this instance, I would like to introduce one of them, the Uda River in the Far East of Russia.
1. Overview of the River
The Uda River (Russian: У́да, Chinese: 乌第河), flowing through the Khabarovsk region in the Russian Far East, is a river rich in natural beauty. It extends 457 kilometers and covers a basin area of 61,300 square kilometers, eventually merging into the Sea of Okhotsk. Although not one of the longest rivers in Russia, it surpasses Japan’s longest river, the Shinano River (367 km).
2. Characteristics of the River
The Uda River’s most captivating aspect is its untouched natural splendor. The river, almost unaltered by human impact as seen in satellite images, snakes powerfully through plains. Numerous oxbow lakes, formed from ancient river paths, are scattered along its banks, presenting a spectacle of natural wonder. In Japan, where rivers have been straightened, there are projects underway to restore their meandering paths. I believe the Uda River could serve as a valuable reference for such initiatives.
The Uda River maintains a pristine environment, supporting a diverse ecosystem. It is especially famous for being home to the gigantic monster Taimen, a dream for fishing enthusiasts. Additionally, its basin hosts a variety of bird species, including the Blakiston’s fish owl, making it a haven for nature lovers and bird-watching enthusiasts.
3. Fish Inhabitants
The river is home to a variety of salmon species. Although an exact list has not been found, literature from the surrounding regions suggests the presence of the following species:
- Brachymystax lenok – Sharp-Snouted Lenok
- Brachymystax tumensis – Blunt-snouted Lenok
- Hucho taimen – Siberian Taimen
- Oncorhynchus gorbuscha – Pink Salmon
- Oncorhynchus keta – Chum Salmon
- Oncorhynchus kisutch – Coho Salmon
- Oncorhynchus masou – Cherry Salmon
- Oncorhynchus mykiss – Rainbow Trout
- Oncorhynchus tshawytscha – Chinook Salmon
- Salvelinus leucomaenis – White-Spotted Char
- Salvelinus curilus – Dolly Varden trout
Of these 11 species, 6 are also found in Japan. The Hucho taimen is related to Japan’s Parahucho perryi, and Salvelinus curilus is related to Salvelinus malma. In contrast, the Brachymystax genus, not present in Japan, sometimes serves as prey for the massive Hucho taimen and consists of carnivorous fish exceeding 50 cm in size. The ecological partitioning of these species is incredibly fascinating. In addition to the salmonids, the river hosts over 10 other families of fish, including the Cyprinidae. Personally, I am keen to see large fish like Pike and Grayling, which are not found in Japan.
The Uda River, with its undiscovered beauty and varied ecosystem, stands as a hidden treasure in the Russian Far East.
<Reference>
1. Froese, R. and D. Pauly. Editors. 2023. FishBase.World Wide Web electronic publication.www.fishbase.org, version (10/2023).
2. Novomodny, G. V. “The preliminary results of contemporary investigations of fish diversity in the Amur Basin: species structure on the boundary of XX-XXI centuries.” First International Symposium “Fish productivity of the Amur River fresh waters and adjacent rivers”. 29 October–1 November 2002. Khabarovsk, Russia. Abstracts. 2002.
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