The Small Box

This small box settled under river side boulders is aimed to catch delicate loach, Niwaella delicata. In autumn, this loaches migrate from stream riffles to stream bank underground water for wintering and spawning. Because of their hard to be seen feature, large part of their spawning ecology in the field is still unknown. 

The box is traditional fishing gear using their such feature. It is said that the right of setting this box is allowed for only few peoples in the village for wise use.

In the mountain, I’m sometimes surprised at the mountain people’s knowledge about fishes.

The Face of Japanese Dace 1

Tribolodon nakamurai

It's jaw is obviously underbite

Immature Japanese dace species belonging to genus Triborodon are difficult to be distinguished from each other.But only Triborodon nakamurai can be detected from other species. It has obviously underbite jaw.

Tribolodon hakonensis and T.ezoe

These two species are uneasy to be distinguished

Incidentally, these two species can be detected by the shape of their anal fin. But very difficult.

Downstream migration start

Plecoglossus altivelis is gathering in the river pool

 Japanese sweet fish, Plecoglossus altivelis is gathering in the river pool. This species usually eats stone algae and makes territory to keep favorite stone area fighting each other. In autumn their will for making territory is gradually weakened. They will migrate downstream to the sea nearest riffle for spawning.

The appearance of fishes

Niwaella delicata

Delicate loach, Niwaella delicata, lives in mountain rivers in central Japan. It’s Japanese name “Ajime-Dojyo” means “delicious loach”. This species has been eaten by people living in mountain region and very delicious. When I see them underwater, I always observe them impressed by their life activities and never think it looks delicious. But , once I take them up over the water, it suddenly seems delicious. How selfish human being are.

Green-red

Oncorhynchus masou

In Shiretoko world heritage,Hokkaido,Japan,the spawning season of cherry salmon,Oncorhynchus masou,is closing to finish. A few females were making spawning red. Whenever I watch it,I think their last green-red coloration is very beautiful.

At the river mouth

Oncorhynchus Keta jumping out from surface at the river mouth

Chum salmon,Oncorhynchus Keta,was migrating into river from sea. Some individuals jumped out from surface in Shari river ,Shiretoko world heritage,Hokkaido,Japan. This picture is not so artistic,but I got some satisfaction when I could took the picture of jumping.

In the ordinary dich

Pungitius sp.

After my survey I traveled around Akita pref., northern part of Japan,searching for ninespine stickleback, Pungitius sp.. By several hours search,I could find them in the narrow ditch. Japan is the northern limit of their distribution. In the south part of Japan, their habitat was dependent on spring cold water and the populations of Kinki region were already extinct because of the disappearance of it. In the high elevation area of north Japan,the water is cold even in summer and they would have been able to live such ordinary concrete dich. This species strongly impress me the vulnerability of distribution edge populations.

Narrow concrete