FISHERY BULLETIN: VOL. 81, NO. 4 



I20°W 



FIGURE 1.— Geographic region inhabited by the central population 

 of northern anchovy. Ichthyoplankton samples were collected along 

 CalCOFI survey lines. Location of stations is indicated only on line 

 93.3. Samples of juvenile anchovy were collected along the mainland 

 coast. In 1978 these samples were obtained from the bait fishery 

 from Pt. Conception to the United States-Mexico border. In 1979 

 samples were collected with a midwater trawl from Pt. Conception to 

 Blanca Bay. 



dance along CalC OFI lines 60-110. The catch at each 

 station was adjusted for volume of water filtered and 

 weighted by the distance to adjacent stations along 

 the line. Abundances along unsampled lines were 

 estimated from abundance in adjacent lines and 

 cruises. A more complete description and further 

 analyses of these data are in Hewitt and Methot 

 (1982). 



The mean and variance of date of larval catch were 

 calculated for each cruise. Each station's contribu- 

 tion to these statistics was weighted by the distance 

 to adjacent stations and by the catch of larvae. The 

 effective duration of each cruise was considered to be 

 ±2 standard deviations of catch date. 



Juvenile Northern Anchovy Samples 



During the period 28 October-14 December 1978, 

 742 



30 samples of northern anchovy were collected from 

 bait receivers at sport fishing docks from San Diego 

 to Pt. Conception, Calif. A total of 1,101 fish were 

 measured, but sample size varied from 11 to 86 fish 

 so each fish' s contribution to the overall size distribu- 

 tion was weighted by the inverse of sample size. From 

 15 of the 30 samples, 141 fish were aged using daily 

 increments in otoliths. 



During 1-19 November 1979, specimens were 

 obtained from samples taken with a 15 m midwater 

 trawl on a survey conducted by the California 

 Department of Fish and Game (CFG) to investigate 

 the abundance of juvenile northern anchovy (Mais 

 1980). Trawls were taken parallel to the coast be- 

 tween the 30 and 90 m isobaths at 7.4 km coastwise 

 intervals between Blanca Bay, Baja California, and 

 Pt. Conception, Calif. Past trawl surveys indicate 

 that the juveniles are concentrated into the 

 nearshore zone (Mais 1974). A total of 2,356 fish 

 were measured from the 93 positive trawls; sample 

 size typically was 25 fish per trawl. In addition, 10 of 

 the 25 fish per trawl were aged by CFG personnel 

 using annual growth marks in otoliths (Collins and 

 Spratt 1969). Juveniles are defined here as those fish 

 with no otolith annuli. The fraction of fish with no 

 annuli in each 5 mm size interval was calculated 

 (Table 1). From 8 of the 93 samples, 129 fish were 

 aged using daily increments in otoliths. 



Size distributions were calculated in each of three 

 alongshore regions: North of Pt. Dume (north), San 

 Diego to Pt. Dume (central), and south of San Diego 

 (south). These regions were selected on the basis of 

 the distribution of samples in 1978 and minima in the 



TABLE 1. — Frequency of northern anchovy with and 

 without otolith annuli. Specimens were collected by 

 trawl during November 1979 (Mais 1980). Results are 

 stratified by region and 5 mm size interval. 



