the eyeball is flush with the spindle-shaped aurfaee of the nead (at an 

 acute angle to the center line of the body) , and both eyes are directed . 

 somewhat forwar3o At such times it can be said that ths eyes are a bit 

 more far-sighted than when the vision is directed to the sides or obliquely 

 to the rear,. This means that when fishing it is ineffective to throw 

 bait close to the sides of the body^ The superior- direct muscle and the 

 s-jperior oblique muscle are stronger than the corresponding inferior 

 muscles, and because of this the skipjack's eye can more easily be turned 

 upward than downwardo Consequently it is thought that the fish cannot 

 see very w^ll below the level of its bodyo Since the -apper forward edge 

 and the lower rear edge of the eye socket have eoncavitisSj it seems that 

 i/isual power is especially great to the upper front and the lower rear„ 

 The field in which rather far vision is possible lies from obliquely 

 ahead to straight ahead of the hodjo and vision must be best along a 

 prologation of the center axis of the bodyo Because the pupil of the 

 skipjack's eye is large and ellipsoid in shape its field of vision both 

 ahead and to the rear is ma^h greater than that of the human eye„ When 

 the skipjack strongly contracts the internal direct Tirascie, the eyeball 

 is directed obliquely forwardp the line of sight is shortened, the convexity 

 of the crystalline body is somewhat deor-?ased, and the vision becw-mss 

 remarkably far-sightedo Depending on the clarity of the water^ it 

 appears that the vision extends to upwards of 60 feet. As a result of 

 having such powers of sight the skipjack can swim at speeds of 60 to 70 

 knots per hour without colliding with anything and can swim about in large 

 schoolSo They can also, relying pi5.rtly on their instincts, surround large 

 schools of sardineSo It is entirely due to its excellent eyesight that the 

 skipjack can be readily taken by fishermeUo That is to say,, it is because 

 the skipjack is far=sighted that it can see the chumming bait from a 

 distance^ and when it comes in close in order to taks the bait, it becomes 

 unable to distinguish the artificial lures from the live bait. If 

 artificial lures are used when the fish are being attracted from a distance, 

 they are ineffective because the fish have good enough vision to distin- 

 g-dish themo Such rores should be used after the skipjack have been 

 brought in closer The practice of spraying water while fishing with pole 

 and line gear ie Jso based on this characteristic of the skipjack,," 

 Fishing methods, should be thoroughly thought out in order to take advan- 

 tage of the skipjack's far-sightednesso 



Paragraph ?. Sv/imming Characteristics 



(a) Sh£. k^asscciated skipjackj whale-associated skipjack==> These are skip- 

 jack £-hoois which follow the lead of kambeisame /"isasking sharks?_7 

 and ?:rdine whales„ The sharks and whales are wily enough to steal the 

 sarcmes which the skipjack round up for food;, but the skipjack can thus 

 take refuge far out at sea from the striped marlin which attack their 

 schoolSj so it is a kind of cooperative living in which the skipjack and 

 the sharks and whales mutually help each cthero This phenomenon is often 

 seen in the North?-a-tern and Zcran areaSo 



(b) Drif twood-associatea ■■-' S\^z\ "•..•: hoo'^s are most often seen in the Zunan 

 Kinan, and Satsunan ar :.oo These are schools which swim along with a 

 drifting logo (Logs which float vertically are more favored than those 



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