Figure 5. — Seasonal distribution of oceanic fish 

 school and bird sightings. 



and the South Equatorial Current south of the 



It is evident from the 

 sighting records In table 3 

 that there was great varia- 

 tion In the numbers of birds 

 and fish schools seen In dif- 

 ferent parts of the oceanic 

 zone. It is Impossible to 

 examine this variation to 

 determine longitudinal trends, 

 but sampling in the central 

 portion of the area (140° to 

 170°W. longitude) is adequate 

 to permit study of latitudi- 

 nal variation. Considerable 

 interest is attached to lati- 

 tudinal variation because the 

 sightings were made over the 

 three current systems of the 

 equatorial Pacific: the 

 North Equatorial Ciirrent, 

 lying roughly north of 10°N. 

 latitude, the Countercurrent 

 between 5° and 10°N. latitude. 

 Counts rcurrent . 



The rate of sighting birds and fish schools varied considerably eunong the 

 different current systems (fig. 7) and within current systems. In the North 

 Equatorial Current, north of 20°N., abundance is very low, though of course the 

 sample la inadequate. Between 10° and 20ON. abundance is greater, though still of 

 a rather low order of magnitude. In the Countercurrent abundance Is high, an ob- 

 servation first made by Brooks (1934), who noted that birds were more abundant in 

 that region than to the north or south during a crossing from San Francisco to 

 Tahiti near 140°W. longitude. Birds and fish schools are relatively scarce in the 

 South Equatorial Current between the Equator and 5°N. latitude. South of the 

 Equator our observations suggest a large population of birds and fish (fig. 7), but 

 examination of the field records shows that nearly all of the schools of fish were 

 sighted during one week of February 1952, and very few sightings were made during 

 the balance of the year (the observations were distributed through seven months). 

 This is not typical of the Information from the other areas, for the field records 



show that the fish schools 

 and birds noted were well 

 distributed in time and space. 

 Thus we are inclined to the 

 view that the high rate of 

 sighting south of the Equator 

 (fig. 7) is in part a sam- 

 pling accident, and that the 

 information is not strictly 

 comparable with that obtained 

 north of the Equator. 



The distribution of 

 surface schools and bi'rds 

 (fig. 7) is different from 

 the distribution of sub- 

 surface or deep-swimming 

 fishes, particularly the 

 yellowfln tuna, as noted by 

 Murphy and Shomura (1953a, b). 

 These papers report the re- 

 sults of systematic longllne 

 fishing across the equatorial 

 current systems. The yellow- 

 fln catches summarized in 

 figure 8 show that, on the 

 on of number of schools sighted average, abvindance is zero in 

 an waters and oceanic waters. the North Equatorial Current, 



HAWAIIAN ISLANDS 



ALL OCEANIC OBSERVATIONS 



Id 



Figure 6.--Comparls 

 per day in Hawaii 



10 



