440 KAMAKICHI KISHES'OUYE: 



most abundaiit ia waters of lO-lS*^ C. Tlius tLe optimum temperature for 

 tills s[5ecies is lower than that of the other tiumies iu om- watei-s, as well as 

 that of the common Atlantic tunny. 



When albacores or sjoear-fishes l:«giu to l)e caught, tliis timuv's season is 

 nearly over. It feeds on different kinds of fish, more or less jjelagic in habit, 

 such as sardine, anchovy, flyiug fish, scad, sand-eel, etc. ; but sometimes fishes 

 li^■ing near the bottom are found iu the sto:uach. Calamaries and pteropods ; 

 Pyrosoma : pelagic crustaceans, such as Ev/phausia, Sergestes, AcantJiepkyra, 

 larvae of Brachj-ura and Stomatoix)da, anomalous Ampliipoda, etc. are also 

 found in the stomach. 



Tliis sjiecies is closely alhed to the Iilue-finned tuna or leaping tuna of 

 the Californian coast, but differs fi-om it iu the colour of fins, and in the mode 

 of ramification of canals of the cutaneous blcod-vessels. A similar or the 

 same species is said to inliabit the Hawaiian watei-s ; but I have not yet had 

 a cliance to investigate tliis. 



Tunnies are migratory, Imt they resort and seem to stay for a wliile at the 

 tap of deep banks, often 200 m deep. In the vicinity of such banks tunnies 

 seem to find plenty of food. Tlie presence of tunnies in deep water is often 

 detected by fishermen from the lJella^^or of sea-gulls, flying fast in a lauch 

 dLs^jersed wide cii'cle, or fi'om cncular or oUong waveless s^xits, ca. 1 m in 

 diameter, produced for a tiree at the surface of the sea. Tliese spots ai"e 

 called "nagi", meaning calm, waveless, and are Injlieved l\v fishermen to 

 come from the oil of fish devom'ed by tunnies ; 1 uit as tunnies mostly engulf 

 their prey in totu, and moreover as I did not oljserve any glittering iridescence 

 in these spots, the explanation is not satisfactory. 



Tunnies are devoured by kUler-wkiles which are said b.) catch them 

 nt the na^De and kill them immediately, so tliat they fear killers so greatly 

 tliat they are fi-ighteued away seieral miles from the spot where tliese ferocious 

 enemies are foimd. Thus catches made by pound-nets vaiy greatly according 

 to üie feivoittable or unfavourable proximity of Idllera. Sometimes tiumies leap 

 on l)eaches recklessly to escape horn these enemies. 



In their northerly migi'ation tunnies swim quite near the coast, and are 

 caught iu jwund-nets, wliich are set iu a deioth of about twenty meti-es. 



Small fish of about 25 cm, weighing ca. 20 g in weight are caught 



