千曲川に於ける水産資源の流下に就て

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書誌事項

タイトル別名
  • Studies on the Fisheries Resources flowed down
  • チクマガワ ニ オケル スイサン シゲン ノ リュウカ ニ シュウテ

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The quantities of fisheries resources, chiefly fishes and their foodbeings such as larva of insects, were investigated which flow from Tikuma-River into the passage of the Ueda Branch of the Central Fisheries Station of Japan, and these were collected by an equipp-ment at the entrance of the experimental ponds. And it was concluded that the all resources which flowed down through Tikuma River in conformity with' the volume of water measured by water-meter.<br> The volume of water flowed into ponds are 30 thousands m3 per day during the time from the last ten days of June to the first ten days of September, 16 thousands m3 from the middle of Sept ?? ber to the last ten days of Octorber, 7 thousands m3 in November, and in which the numbers of fishes 15 thousands, weight of food-beings 21kg. through these period in 1948, and the numbers of fishes 7 thousands, weight of food-beings were 15kg. in 1949. These fishes which flow down into pond were many at the day, and the food-beings were many at the next day of the largest volume of water in river. And there are many fluctuate at the number of fishes or weight of food-beings which flow down into pond, althogh the volume of water were similar from June to September, this is the reason the volume of water are much flactuate in the main stream. The fishes and food-beings were less since the middle of September, it will be these individuals are decreased for the flood, and also is not the season of insects propergation.<br> Then the number of these fishes were presumed as 4380 thousands in 1948, 4100 thousands in 1949, and food-beings are 6000kg. in 1948, 1698kg. in 1949 which flowed down Tikuma River during above season.<br> So, it should be considered to prevent these fishes and food-beings from flowing into the water passage such as the conducts for irrigation or hydroelectricity.

収録刊行物

  • 日本水産学会誌

    日本水産学会誌 16 (5), 184-191, 1950

    公益社団法人 日本水産学会

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