Using model fish-ways and some kinds of fishes, we studied the rate of ascent and obtained the following results.
(1) The distribution of fishes in fish-ways is represented by the next formula (1): nk ?? ak, ……………………………………… (1) where nk is the number of fishes in the kth compartment of fish-way and a is a constant.
(2) The percentage, pv, of the number of fishes which reach the top of a fish-way having v compartments in unit time is represented by the next equation (2): pv=p1av-1, …………………………………… (2) where p1 is the percentage of fishes which enter the first compartment of fish-way in unit time.
(3) The temperature of water has a great influence upon the rate of ascent.
(4) The slope of fish-way has a great influence upon the rate of ascent, and the rate of ascent decreases as the slope of fish-way increases.
(5) The rate of ascent depends upon the ratio of size of fish to level-difference in adjacent two compartments.
(6) The rate of ascent has a maxium value at a definite value of quantity of flow, and the quantity of flow giving the maximum rate of ascent much differs with the form of partition wall.
