COMPARATIVE STUDY OF SCOMBROID FISHES. 
441 
with rod and line late in summer. Such immature fish are called “ imoshibi ” 
in Miyazaki-ken. Still smaller fish are called “ kakinotane ” in Kanagawa- 
ken, and “abuko” or “ bints u ” in Miye-ken. These immature fishes are 
found in association with Auxis, feeding chiefly on pelagic crustaceans. These 
immature fish grow to a length of ca. 40 cm, weighing ca. 1 kg in winter, 
and in the next summer 2-3 kg in weight. 
In summer, June and July, the reproductive glands are very large, and 
the fish swarm near the surface of the water, often showing their dorsal fins 
out of water. This is the case in the northern parts of our waters, both on 
the Pacific and Japan Sea coasts. These mature fishes are associated with 
immature fishes. I have, however, not yet examined a tunny with fully ripe 
reproductive elements, and in August the reproductive glands are found spent. So 
that we are inclined to believe that the tunny spawn in offshore waters. Oil the 
southern part of Kyushyu and also off the Pacific coast of the central part 
of Hondo, we find small immature tunnies in summer and autumn. In these 
waters the common tunny with ripe reproductive glands is not known. But 
it is difficult to believe that those immature fishes migrated from the northern 
waters. 
Tunnies are caught more on dark nights, and before a storm. When the 
weather is warm with a southerly wind, tunnies come near the surface of 
the water, and a good catch by drift-nets is expected. On a day of northerly 
wind driftei‘3 do not go out fishing. They are said to swim against the 
current, especially when they are near the coast, hence they enter bays or 
inlets in low tide and seek off-shore grounds in high tide. Tunnies dislike 
a water of a low density, so that they do not approach the coast on a rainy 
day, nor approach the mouth of a river. They are found in a water of ca. 
1.024-1.025 in density. 
It is said that when a shoal of tunnies is frightened at something ahead 
of them, every tunny of the shoal turns back immediately just at the spot 
where it happens to be. Thus the liiudermost fish lead the school when 
retiring. In 1921 a few immature tunnies were caught off Sendai in set-nets, 
at a depth of ca. 300 m. The nets were for a kind of deep-sea sharks. These 
tunnies were probably entangled, while the net was being hauled in, or when 
letting it out in the sea. 
