RECORDS AND OBSERVATIONS FROM PLANKTON GRID STUDIES 

 OFF BAJA CALIFORNIA, APRIL 1952 



by 



David Kramer 



Fishery Research Biologist 



Bureau of Commercial Fisheries 



U.S. Fish and Wildlife Service 



La JoUa, California 



ABSTRACT 



Data are presented for a grid survey conducted for 5 days in April 1952. The 

 cruise was made by three vessels; one made a daily survey of a square grid of 25 

 stations spaced 4 miles apart, one maintained an anchor station on this pattern, and 

 one followed a 10-meter drogue drifting through the pattern. 



The data deal with the eggs and larvae of the Pacific sardine ^Sarrfiraops caerulea) 

 and the larvae of other commercial species; the northern anchovy (EngrauUs mordax), 

 the jack mackerel ^rrac/iurus symmetric us), the Pacific mackerel (Pneumatophoms diego), 

 the hake (M erluc cius productus), and rockfish (Sebastodes spp.). All the above larvae 

 except those of the hake and rockfish are reported by size. Data are also included for 

 the larvae of a deep-sea smelt Lewoglossus stilbius, and a lanternfish Lampanyctus 

 mexicanus, because of their abundance on this survey. Distribution diagrams show 

 the more abundant fish larvae and plankton volumes on the grids. Plankton volumes 

 are reported and differences in day and night collections are discussed. 



Introduction 



This paper reports on the data gathered on 

 a special cruise made in April 1952. The 

 work was designed to investigate some of 

 the problems encountered in the sampling 

 techniques of the California Cooperative 

 Oceanic Fisheries Investigations (CalCOFI) 

 in monthly surveys off the Pacific coast of 

 the United States and Baja, California. 



The CalCOFI are sponsored by the Cali- 

 fornia Marine Research Committee. The co- 

 operating agencies in these investigations 

 are the U.S. Bureau of Commercial Fisheries, 

 the Scripps Institution of Oceanography, the 

 California Department of Fish and Game, 



Hopkins Marine Station of Stanford University 

 and the California Academy of Sciences. 



The data are presented in figures and 

 tables in the same manner as the data re- 

 ported by the Bureau of Commercial Fish- 

 eries Biological Laboratory atLa Jo Ila, Calif., 

 on the sardine eggs and larvae and other fish 

 larvae for 1950-57 (Ahlstrom, 1952, 1953, 

 1954a, 1958, 1959; Ahlstrom and Kramer, 

 1955, 1956, 1957). The fish larvae reported 

 for this cruise include the following com- 

 mercial species: Pacific sardine (Sardinops 

 caerulea), northern anchovy (EngrauUs mordax), 

 jack mackerel (Trachurus symmetricus). Pacific 

 mackerel Pneumatophorus diego, hake (Merluccius 

 productus), and rockfish (Sebastodes spp.). Two 

 other species are included because of their 



