440 
KAMAKICHI KLSHINOUYE : 
most abundant in waters of 10-15° C. Tlius the optimum temperature for 
this species is lower than that of the other tunnies in our waters, as well as 
that of the common Atlantic tunny. 
When albacores or spear-fishes begin to be caught, this tunny’s season is 
nearly over. It feeds on different kinds of fish, more or less pelagic in habit, 
such as sardine, anchovy, flying fish, scad, sand-eel, etc. ; but sometimes fishes 
living near the bottom are found in the stomach. Calamaries and pteropods ; 
Pyrosoma ; pelagic crustaceans, such as Euphausia, Sergestes, Acanthephyra, 
larvae of Brachyura and Stomatopoda, anomalous Ampliipoda, etc. are also 
found in the stomach. 
This species is closely allied to the blue-finned tuna or leaping tuna of 
the Californian coast, but differs from it in the colour of fins, and in the mode 
of ramification of canals of the cutaneous blood-vessels. A similar or the 
same species is said to inliabit the Hawaiian waters ; but I have not yet liad 
a cliance to investigate this. 
Tunnies are migratory, but they resort and seem to stay for a wliile at the 
top of deep banks, often 200 m deep. In the vicinity of such banks tunnies 
seem to find plenty of food. The presence of tunnies in deep water is often 
detected by fishermen from the behavior of sea-gulls, flying fast in a much 
dispersed wide circle, or from circular or oblong waveless spots, ca. 1 m in 
diameter, produced for a time at the surface of the sea. These spots are 
called “ nagi ”, meaning calm, waveless, and are believed by fishermen to 
come from the oil of fish devoured by tunnies ; but as tunnies mostly engulf 
their prey in toto, and moreover as I did not observe any glittering iridescence 
in these spots, the explanation is not satisfactory. 
Tunnies are devoured by killer-wliales which are said to catch them 
at the nape and kill them immediately, so that they fear killers so greatly 
that they are frightened away several miles from the spot where these ferocious 
enemies are found. Tlius catches made by pound-nets vary greatly according 
to the favourable or unfavourable proximity of killers. Sometimes tunnies leap 
on beaches recklessly to escape from these enemies. 
In their northerly migration tunnies swim quite near the coast, and are 
caught in pound-nets, wliich are set in a depth of about twenty metres. 
Small fish of about 25 cm, weighing ca. 20 g in weight are caught 
