A couple of weeks ago, I visited Okutama for a hike. Okutama is a beautiful mountain area with great rivers and surprisingly it’s still 
in the Tokyo area! For a clearer understanding, it actually only takes 90 min to Shunjuku on the Chuo-line, so it’s far but not too far.
While I was t
here, I came across the Shiromaru-dam fish passage. This was made in 2002 April. The entire dam is 331.8m and the fish going across are: Yamame trout, Cherry trout and Ayu fish. These fish were let out in the river by hand as an experiment to see if the pathway worked. Naturally, other fish were found utilizing the pass way such as: Japanese dace, Rhinogobius, other trouts and many more.
The stairs the leads up to the pathway have walls that are higher than the water level so that the fish can rest. In the pathway, there are small holes carved for fish to swim through as it leads to the other end of the river.
The Shiromaru-dam fish passage is the largest in Japan, and the nature surrounding the dam was wonderful.
Human Ecology: Rivers 
It looks like you had a great time hiking in Okutama. It’s a great area and I go there often with my family for hiking and dipping in the rivers there. Thanks for the great photos and for looking up all the fish names!
LikeLike