140 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



300 



050 



100 



150 



200 



PLANKTON VOLUMES IN CC. PLANKTON VOLUMES IN CC. 



Figure 11. — Plankton abundance in the western Pacific: Results given are settlement volumes of total (?) plankton 

 obtained by vertical hauls at 50 to meters along 134° E. longitude. A. As reported by Tokioka (1941!) for 

 three cruises, December 1939, March 1940, and May 1940 (averaged by the senior author). B. As reported by 

 Haneda (1942) for one cruise, December 1939. 



(1935), summarizes the results as follows (the 

 volumes expressed are catches per 1-hour haul 

 using li/,-meter stramin nets with 50 and 100 

 meters of wire out) : 



A notable fact here is, that we find specially large 

 volumes in the eastern part of the Pacific, from the Bay 

 of Panama to the Marquesas Is., with a distinct maxi- 

 mum (1,125 cc.) at St. 2,558, which lies west of the 

 Galapagos. On the stretch from the Marquesas to 

 Tahiti we have decreasing quantities of plankton (ca. 

 150-200 cc. ), whilst on the sections from Tahiti — Cook 

 Island (Rarotonga) — Samoa — Fiji the quantities are 

 very small, less than 100 cc. We thus have extremely 

 little macroplankton in this area of the central part of 

 the Pacific, yet a series of stations just north of Samoa 

 yielded somewhat larger quantities (ca. 100-260 cc). 

 From Fiji to New Caledonia also the quantity of macro- 

 plankton increases (ca. 125-210 cc.) and a further in- 

 crease is shown in the section from New Caledonia 

 down towards Kermadec Islands. 



For comparison, in the North Atlantic the ex- 

 pedition obtained volumes ranging from 90 to 

 7,250 cc. per hour of hauling. 



The very extensive plankton data presently be- 

 ing collected by the California Cooperative Sar- 

 dine Research Program (California, Progress Re- 

 port 1950, and unpublished data) are quite com- 

 parable to our own in most respects. Similar nets 

 have been used by both investigations, and the re- 

 sults are expressed in similar units. Whereas the 

 Sardine Research Program employed an oblique 

 tow to a depth of 70 meters for the collections re- 

 ported here, our oblique tow descended to 200 

 meters. This difference in sampling method prob- 

 ably had no great influence on the difference in re- 

 sults obtained. If we consider 22 of their farthest 

 offshore stations, located between 25° N. and 33° 

 N. latitude and visited in September 1950, we find 

 that the average for the group was 0.057 cc./m. 3 , 

 which is approximately equivalent to our average 

 (table 11) for the South Equatorial Current near 

 the Equator but 3 times the average for the North 

 Equatorial Current. Values for regions of up- 

 welling close in to the California coast were as 

 high as 14.595 cc./m. 3 in February 1950. This is 



