大西洋赤道付近におけるキ八ダの釣獲率経月,経年変化と表面水温の経月,経年変化との関係

抄録

The author has studied on the relation between monthly variation of hooking-rate of yellowfin tuna and that of surface water temperture and between annual variation of hooking-rate of the fish and that of surface water temperature, in the Tropical Atlantic Ocean.
The data on hooking-rate and surface water temperature had already been provided for the purpose of studying seasonal variation and annual variation of hooking-rate.
The hooking-rate and surface water temperature in Fig. 2 are mean monthly, sub-area values for period from 1957 to 1962 which have been calculated and obtained from values having been given by month and by latitudinal and longitudinal division by 5°.
The hooking-rate and surface water temperature in Fig. 5 are mean annual values calculated and obtained from values given by month and by sub-area.
The auther has obtained the following results:
1) The monthly variation of hooking-rate of the fish has been concerned with that of surface water temperature; the hooking-rate was high in periods when the surface water temperature was high and low in periods when the surface water temperature was low (Fig. 2, Fig. 3).
2) The annual variation of hooking-rate of the fish has been concerned with that of surface water temperature; the hooking-rate was high in years when the surface water temperature was high and low in years when the surface water temperature was low (Fig. 5).
3) Accordingly it is presumed that the hooking rate will be high in any period and year when the surface water temperature is high, and low in any period and year when the surface water temperature is high, and low in any period and year when the surface water temperature is low.
4) But the monthly variation of the hooking-rate has been reversely concerned with that of surface water temperature in area E; the hooking-rate was low in periods when the surface water temperature was high. Also the annual variation of the hooking-rate has not been concerned with that of surface water temperature in areas F and H.
5) In view of all above it is presumed that the width of adaptability of yellowfin tuna to water temperature is very large.