PARRISH ET AL.: REGIONAL VARIATIONS IN NORTHERN ANCHOVY 



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FlGURE 1.— Mean length of aged and unaged 

 northern anchovies and the number of an- 

 chovies by half degree of latitude 



30 

 LATITUDE 



The data were inadequate to calculate growth 

 curves or age composition on the one-half degree of 

 latitude interval used in Figure 1; therefore, geo- 

 graphical regions were selected based partially on 

 the number of observations. For example, the 

 southern and central Baja California and central 

 California areas, which had fewer samples, were 

 more widely spaced than the southern California and 

 northern Baja California areas. Nearly all of the an- 

 chovy samples taken south of lat. 32°N or north of 

 lat. 34°N were taken within one-half degree of the 

 coast. The lat. 32°-34°N area included a large amount 

 of samples taken further than one-half degree from 

 the coast. This area, the Southern California Bight, 

 contains numerous islands and basins; we, therefore, 

 divided it into regions which approximate the natural 

 basins described in Emery (1954) (Fig. 2). 



RESULTS 



Growth 



Earlier studies on northern anchovies from British 

 Columbia (Pike 1951), northern California 

 (Waldvogel 1977), central California (Clark and 

 Phillips 1952), and southern California (Spratt 1975) 

 showed considerable variation in their growth (Fig. 

 3A). Anchovies in British Columbia, lat. 49°N, and 

 northern California, lat. 41°N, are of the northern 



stock (Vrooman et al. 1981) and have a summer 

 spawning season. Anchovies in southern California, 

 lat. 33 °N, are of the central stock, whereas those in 

 central California, lat. 36°N, are considered to be 

 a mixture of northern and central stocks (Vrooman 

 et al. 1981); anchovies in both southern and central 

 California have a late winter (February-April) spawn- 

 ing season (Parrish footnote 3). Anchovies in British 

 Columbia were the fastest growing of all the four 

 areas in their first year of life, whereas anchovies 

 in northern California were the slowest. Anchovies 

 in central and southern California showed similar 

 growth rates after their first year of life; however, 

 the growth rate of anchovies in central California 

 was greater than the growth rate of those in 

 southern California in their first year. 



Our study shows that the growth of anchovies has 

 a distinct geographical pattern. Anchovies sampled 

 in the Central California region (CC) and the off- 

 shore area of the Southern California Bight [i.&, San 

 Nicolas (SN) and Tknner and Cortez Banks (TCB) 

 regions] have the fastest juvenile growth (Fig. 3). An- 

 chovies in these areas attain an average length of 

 120 mm before they are IV2 yr old. In the inshore 

 areas of the Southern California Bight and in Baja 

 California there is a continuous decline in the growth 

 rate associated with decreasing latitude (Figs. 3, 4). 

 Anchovies reach a mean length of 120 mm at about 

 age 2 in the Santa Barbara Channel region (SBC) 



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