A Survey of Tuna Fishing Grounds in the Marshall and Caroline 



Islands 



Since the end of 1938, when a large number of Japanese fishing vessels 

 began to operate among the South Sea Islands, the tuna fishing grounds of 

 t&ese islands have attracted the attention of the world. 



At present, however, the area where the Japanese tuna vessels fish 

 is limited to one section of the central Caroline group. The principal 

 fishing grounds, in general, lie between 1UA° E longitude (near Woleai 

 Island) and 153 E longitude (near Namoluk Island) and between the Equator 

 (0°) and 7° N latitude (near Truk) , although recently there have been in- 

 dications of a gradual shift eastward. This area is washed by the Equa- 

 torial Counter-current. The object of this survey conducted by the Zuiho 

 Maru was to determine whether good tuna fishing grounds exist in the 

 Equatorial Counter-current area to the east and south of Pcnape, Kusaie, 

 and Jaluit Islands. 



The survey group departed from Palau on 10 November last and returned 

 on 28 December; a total of J+9 days was spent on this survey. Since the 

 detailed report on this survey is at present being compiled separately, a 

 rough report is submitted here as a reference for persons and industries 

 concerned. 



Brief description of the fishing grounds . 



No. 1. This fishing ground is located about 55 miles west of Tbleai. 

 Island and, judging from the WSW flow of the current, is in the Equatorial 

 Current area. Since this vessel had other official business to attend to 

 at Tfcleai, the survey of this location was conducted en route to that island. 

 The survey group expected little from this ground; consequently, only 20 

 baskets were used. 



Mo. 2. This fishing ground is located about 130 miles SE of Woleai and 

 south of Ianthe Shoal. The E/S flow of the current clearly indicates that 

 it lies within the Equatorial Counter-current. One hundred baskets of 

 tuna longlines, each having six hooks, were used, making a total of 600 

 hooks fished. The types of fish caught are shown in the table and the 

 catch ratio was 1.5. / TN. The catch ratio is the number of tuna and 

 spearfish taken per 100 hooks fished. J 



No. 3. This ground is located about 110 miles SE of No. 2 fishing ground 

 or about 2A0 miles SE of Woleai. The E/S flow of the current clearly 

 indicates that it lies within the Equatorial Counter-current. A rather- 

 swift flow is indicated by the velocity of one knot. A total of 100 

 baskets were used and the tuna catch ratio of 9.3 indicates that the re- 

 sults were good. 



No. U. This fishing ground is located about 100 miles S/W of Truk and, 

 judging from the SE/E flow of the current, is also within the Equatorial 

 Counter-current. Because of the condition of the fish hold, the number of 

 basket;; used was cut down to 50. The catch ratio was 5.0, which indicates 

 a good fishing ground. 



No. 5. This fishing ground is located about 120 miles SE of No. L, or 

 about 200 miles SSE of Truk. The easterly flow of the current clearly 

 indicates that it too lies in the Equatorial Counter-current area. The 



