ZOOPLANKTON VOLUMES OFF THE 

 PACIFIC COAST, 1959 



by 



James R. Thrailkill 



Fishery Research Biologist 



Bureau of Commercial Fisheries 



U. S. Fish and Wildlife Service 



La Jolla, California 



ABSTRACT 



Basic data on volumes of zooplankton off the Pacific coast in 1959 are given, 

 together with data for all plankton hauls taken on survey cruises of the California 

 Cooperative Oceanic Fisheries Investigations. Plankton volumes in survey area 

 paralleled those of 1958 and averaged less than one-third as much as during 1951-56. 

 Distribution charts showing relative areal zooplankton abundance by month are in- 

 cluded. 



This is the ninth of a series of annual data 

 reports on the plankton volumes collected on 

 survey cruises off the Pacific coast by the 

 California Cooperative Oceanic Fisheries In- 

 vestigations (CalCOFI). Six reports in this 

 series, covering the period 1949 through 1955, 

 appeared under the authorship of "Staff of the 

 South Pacific Fishery Investigations" (1952, 

 1953, 1954a, 1954b, 1955) and contained basic 

 data on the volume of zooplankton collected on 

 monthly survey cruises. Three reports 

 (Thrailkill, 1957, 1959, 1961) contained both 

 basic data and monthly distribution charts of 

 zooplankton volumes for 1956, 1957, and 1958. 

 Charts illustrating the monthly and yearly dis- 

 tribution of plankton for the years 1949-55 were 

 published by Thrailkill (1956). 



CalCOFI research is sponsored by the Cali- 

 fornia Marine Research Committee and carried 

 out cooperatively by the Scripps Institution of 

 Oceanography of the University of California, 

 the Pelagic Fish Investigations of California 

 Department of Fish and Game, the California 



Academy of Sciences, the Hopkins Marine 

 Station of Stanford University, and the Bureau 

 of Commercial Fisheries Biological Labora- 

 tory, La Jolla, California. 



Names of the vessels participating on each 

 of the CalCOFI cruises in 1959 are given in 

 table 1. The Black Douglas, is operated by the 

 Bureau of Commercial Fisheries Biological 

 Laboratory, La Jolla, the other vessels by 

 Scripps Institution of Oceanography. A chrono- 

 logical listing of the CalCOFI survey cruises 

 for 1959, with information on the area covered 

 and the number of stations occupied, is shown 

 in table 2. The stations occupied during 1959 

 are shown in figure 1. 



The plankton samples are used in connection 

 with life history studies of the sardine and 

 other commercially important or potentially 

 important fishes, and also in connection with 

 productivity and zoogeography studies in the 

 eastern Pacific. The former investigations are 

 being conducted by the Bureau of Commercial 



