125° 



120° 



FISHERY BULLETIN: VOL. 87, NO. 3, 1989 



115° 



35' 



30° 



J \ \ lA^* ^ 



Figure 1. — Northern and southern areas, and CalCOFI transect line and station numbers. Each area is 

 divided into "inshore" and "offshore" subsets of stations; the dividing line used in the northern area for 

 1960-65 was closer to shore than that for 1966-69 because the distribution of samples differed. The same 

 areas were used for data from the 1950s, with same inshore/offshore divisions as in 1960-65. 



used published data from 1958 and 1959, during 

 which there was a major El Niiio, compared 

 with 1955-57. Zooplankton from the California 

 CuiTent during these years had been visually 

 classified into 17 categories, and wet weight bio- 

 masses were assigned to each (Isaacs et al. 

 1969). We examined "euphausiid" and "copepod" 

 categories of this data set (assuming from our 

 visual examination that the "copepods" were 

 most similar to our "small zooplankton" cate- 

 gory), selecting those stations which were noc- 

 turnal and within the areas defined in Figure 1 

 during April, July, and October, and separating 

 1955-57 from 1958-59. This resulted in 21 north- 

 ern, 1955-57 stations (13 of which were inshore); 

 49 northern, 1958-59 stations (30 inshore); 118 

 southern, 1955-57 stations (72 inshore); and 110 



southern, 1958-59 stations (63 inshore). We then 

 performed statistical tests analogous to those 

 described above to test hypotheses concerning 

 similarity of geographic and temporal variation 

 of euphausiid and copepod biomasses, and con- 

 stancy of their ratio. 



RESULTS 



Interannual Variation of Euphausiids 

 and Copepods, 1955-59 



Colebrook (1977) demonstrated by multivar- 

 iate analysis overall north-to-south and inshore- 

 to-offshore trends in the annual mean values of 

 zooplankton biomass in the CaUfornia Current. 

 He found that the biomasses of euphausiids and 



686 



