ABSTRACT 



This report provides ichthyoplankton and associated station 

 and tow data from California Cooperative Oceanic Fisheries 

 Investigations (CalCOFI) cruises conducted off California and 

 Baja California in 1981. It is the twenty-third report in a 

 series that presents these data for all biological-oceanographic 

 CalCOFI surveys from 1951 to the present. A total of 978 

 stations was occupied during 7 multivessel cruises over the 

 survey area which extended from Pt. Reyes, California to Pt. San 

 Juanico, Mexico, and seaward to several hundred miles. The 

 data are listed in a series of 6 tables; the background, 

 methodology, and information necessary for interpretation and 

 guantitative analysis of the data are presented in an 

 accompanying text. All pertinent station and tow data, including 

 volumes of water strained and standard haul factors, are listed 

 in the first table. Another key table lists, by station and 

 month, standardized counts of each of the 150 larval fish 

 categories identified from survey samples. This and previous and 

 subseguent reports make the CalCOFI ichthyoplankton and station 

 data available to all investigators and serve as guides to the 

 newly developed computer data base. 



INTRODUCTION 



This report, the twenty-third of a series, provides 

 ichthyoplankton and associated station and tow data from 

 California Cooperative Oceanic Fisheries Investigations (CalCOFI) 

 joint biological-oceanographic survey cruises conducted in 1981. 

 This program was initiated in 1949, under the sponsorship of the 

 Marine Research Committee of the State of California, to study 

 the population fluctuations of the Pacific sardine (Sardinops 

 sagax) and the environmental factors that may play a role in such 

 fluctuations. CalCOFI, known as the California Cooperative 

 Sardine Research Program from 1949 to 1953, was made up of 

 representatives of the South Pacific Fisheries Investigations 

 (SPFI) of the U.S. Fish and Wildlife Service [now the La Jolla 

 Laboratory, National Marine Fisheries Service (NMFS) ] , the 

 Scripps Institution of Oceanography (SIO) , the California 

 Department of Fish and Game (CDFG) , the California Academy of 

 Sciences (CAS) and the Hopkins Marine Station of Stanford 

 University. The first three of these agencies supplied ships and 

 personnel to conduct the sea surveys. NMFS processed the 

 plankton samples and analyzed the ichthyoplankton from them. SIO 

 processed and analyzed the hydrographic samples and measurements 

 and also analyzed invertebrate groups from the plankton samples. 



The boundaries, station placement, and sampling frequency 

 for the CalCOFI survey area were based on the results of joint 

 biological and oceanographic cruises conducted by NMFS and SIO 

 during 1939-41. Those cruises were designed to collect sardine 

 eggs and larvae and associated hydrographic data over the entire 

 areal and seasonal spawning range of the species. On these 

 survey cruises, plankton tows were made to 70 m, a depth which 



