Results 



Horizontal distribution of the tuna. 



From the results of this study, it appears that the tuna occur close 

 to the reef, while the spearfish are found farther offshore. The former 

 are most numerous within 1 to 3 miles of the reef, the latter at distances 

 greater than 3 miles offshore. The greatest number of fish are caught 

 off channel entrances, and where currents meet off the angles and points 

 of islands. No trials were made in the open sea away from the influence 

 of the islands, because of the shortage of time and personnel, and so 

 unfortunately no opinion can be given as to the worth of such fishing 

 grounds. 



Vertical distribution of the tuna. 



The tuna appear to occur at depths of 50 to 60 fathoms in this 

 archipelago. 



1. Determined by correlating oceanographic observations with the body 

 temperature of tuna (taken immediately after capture and before the 

 fish died) . 



2. Tuna were tal en on the long branches with hooks at a depth of about 

 50 fathoms. 



3. When the gear was altered to put all of the hooks down to 50 fathoms, 

 the catch increased. 



Our conclusions are deduced from the above points and, although no 

 final decision can be made yet, it is thought that this matter is worthy 

 of study. 



Density of the tunas 



It would be premature to determine the density of the tuna population 

 in the area on the basis of this one study, but from our results it is 

 difficult to see where the density is remarkably greater than that found 

 in Japanese waters. The results may be conveniently summarized as follows: 



Number of operations 

 Number of times there was no catch 

 Largest catch Yellowfin 



Spearfish 

 Gear used average 



20 

 7 



2 (206.75 lbs.) 

 1 (90.97 lbs.) 



16 baskets 



Remarks 



A study like this one is necessarily very different from a commercial 

 operation. Because we continually moved on from one fishing ground to 

 another and did not regulate the length of our stay on a particular ground 

 according to the good or bad catch which we made there, our catch ratio 

 was comparatively poor. If we were to rely on this catch ratio to discover 

 the best fishing grounds, and try to imagine the amount of fish which 



