Report of a Survey of the Tuna Fishery in Palau Waters 



This study was conducted during operations extendin,'^ from April 1 ^ 19^1 

 to November 8 of the same year,. The area studied was about 15 nautical 

 miles off the eastern shores of PalaUj bounded by north latitude 8° 0' to 

 the northj east longitude 134-° 53" to the east, north latitude 7° 6' 30" to 

 the south, and east longitude 134-° 28 « 30" to the west„ 



The minimum surface temperature was 27o9° and the maximum temperature 

 was 30o2°o The minimum temperature was 0o2O lower and the maximum tempera= 

 ture was 00 4.*^ higher than the surface temperatures in the latter part of 

 19iW)o The water temperature 50 meters below f^e surface showed a minimum 

 of 23o6° and a maximum of 29o4., with an average of 27o5°o The minimum 

 temperature at 100 meters was 1606*^'' and the maximum was 26„2j, an average of 

 2O080 Therefore, it indicated about 6„7° lower than the water temperature 

 at the 50-meter stratum„ However, since the hooks on the long line were 

 suspended at a depth of about 50 meters, it may be safely said that the 

 ternoerat'ire most suitable for the yellowfin tuna during the course of this 

 survey was 27°-28°o (The results showed the same temperature as that of 

 the latter part of last yearo ) 



Direction and Speed of Current 



In the 11 experiments conducted, thp current of NOo 8 fishing ground, 

 which showed tv-ie highest catch ratio of 14.0 16, flowed southwest at a speed 

 of O06 knotSo In fishing ground No, 11, with a catch ratio of 10 „4., the 

 ciHTent flowed to the southwest also at a speed of 0„5 knots. In fishing 

 ground No„ 9, with a catch ratio of 7o9j the current flowed to th^ southwest 

 at a speed of 0o2„ The corrents of the fishing grounds which indicated 

 good results during this period practically all flowed to the southwest 

 and the speed averaged 0o5. The direction of the current was practically 

 the same as that of the latter part of the previous yearo 



The Catch 



In each case it was clear that the y- ;lowfin tuna outnnmborpd the 

 big=eyo' i-nna and f'-e spearfishc As indicated in the fishing c'lart the 

 yellov'T'i '.una in t' is period showed a particularly marked Droj ot^; nn^'oe 

 compared to the latter part of last yearo 



Refer to "Ocp ^raphic Changes and Fishing Conditions in Paxau Waters" 

 for the cause of thr slack in fishing from April to Juneo 



