112 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



life Service, the California Department of Fish 

 and Game, the California Academy of Sciences, 

 and the Hopkins Marine Station of Stanford 

 University — is collecting considerable informa- 

 tion on the zooplankton of the eastern Pacific 

 Ocean in subtropic and temperate latitudes. This 

 organization has supplied our laboratory with 

 copies of its unpublished data, which, when com- 

 pared with our own results, show interesting dif- 

 ferences between the zooplankton crops of the 

 eastern and central Pacific. Reports of many of 

 the expeditions which have entered the Pacific, 

 such as those of the Challenger, the Albatross, and 

 the Meteor, provide extensive information on the 

 systematics and distribution of species or groups of 

 the zooplankton, but supply little quantitative 

 data that may be used to evaluate the zooplankton 

 crop in the different regions visited. 



The authors wish to acknowledge their in- 

 debtedness to Dr. Milner B. Schaefer, 1 under 

 whose direction this project was initiated, and 

 to Dr. Albert L. Tester 2 for his very valuable 

 assistance in the statistical phases of the study 

 and his constructive criticism of the manuscript. 



1 Formerly chief. Section of Research and Development, Pacific 

 Oceanic Fishery Investigations ; presently director of Investiga- 

 tions, Inter-American Tropical Tuna Commission. 



2 Professor of Zoology, University of Hawaii. 



We are also grateful to fellow staff members and 

 the officers and crew of the Hugh M. Smith for 

 their interest and efforts in obtaining this exten- 

 sive series of collections. 



COLLECTION OF ZOOPLANKTON 

 SAMPLES 



AREAS SAMPLED 



This study is based on 210 collections made in 

 the central Pacific on cruises 2, 5, 7, and 8 of the 

 United States Fish and Wildlife Service vessel 

 Hugh M. Smith in 1950 and 1951. Cruise 2 was 

 made in January and February 1950; cruise 5 in 

 June, July, and August 1950 ; cruise 7 in October 

 and November 1950; and cruise 8 in January, 

 February, and March, 1951. Thus, there were 2 

 cruises (2 and 8) at a time corresponding to the 

 northern winter season, and 1 cruise each (5 and 

 7) for summer and autumn. The approximate 

 locations of the stations are shown in figures la 

 and lb, and more exact positions are given in 

 tables 1, 2, 3, and -t. The data are distributed in 7 

 long north-south sections, 6 of which cross the 

 Equator, and in a number of shorter series of 

 stations (cruise 8). 



