Abstract
1. Effect of variations of water temperature on the growth rate. It is believed that the rings on the scale, otolith and centrum of vertebral bone are formed annualy by the cyclic variation of water temperature. Then, if we culture fishes in water of constant temperature, scale rings will not be formed. In order to ascertain this point, I kept trouts at Oizumi experimental station of Tokyo College of Fisheries (Long. 138°24' Lat. 35°50', Height 1000m) from April, 1943 to June, 1945. The result is shown in Table 1 and Fig. 2. From these results we can conclude that growth rate is not constant even if water temperature is constant. Consequently we can not assume that mechanism of ring formation are due to the variation of water only. II. On the determination of death rate. Few results of the determination of death rate of fish by rearing experiments are published. We can get the death rate of traut from the above experiment. I counted dead fish one by one every day and I got a 10 days total of them. The result is shown in Table 2 and Fig. 3-4.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
