PARRISH ET AL.: REGIONAL VARIATIONS IN NORTHERN ANCHOVY 



patterns which are not statistically different (a = 

 0.01), and since the two regions are adjacent we have 

 considered them together. Also there is no signi- 

 ficant difference (a = 0.01) in adult growth in the 

 Catalina Basin and the Santa Barbara Channel 

 regions, but since these regions are geographically 

 separated we have retained them as separate 

 regions. The relatively large standard deviations of 

 the regression slopes (Ikble 2) for fish from the Cen- 

 tral California and the Sebastian Viscaino Bay and 

 the Southern Baja California regions may indicate 

 that these regions are the most likely to have mix- 

 tures of more than one stock. 



There was no significant difference {a = 0.01) be- 

 tween growth of adults in the best growth regions 

 (Ensenada, Cape San Quentin, and Central Califor- 

 nia). The difference between the Coronado Escarp- 

 ment and the Santa Barbara Channel regions is not 

 significant at the a = 0.1 level nor are the differences 

 between the Catalina Basin, combined San Nicolas- 

 Tknner and Cortez Banks, San Pedro Channel, and 

 combined Sebastian Viscaino Bay and Southern Baja 

 California regions. 



Tknner and Cortez Banks, and Catalina Basin) dif- 

 fer from the other regions in that they are dominated 

 by fish 3 yr and older (Fig. 6A, Tkble 4). Central 

 California and Tknner and Cortez Banks also have 

 substantial percentages of young-of-the-year fish, 

 whereas the other two regions do not. 



Anchovies in the three inshore regions of the 

 Southern California Bight (Santa Barbara Channel, 

 San Pedro Channel, and the Coronado Escarpment) 

 have very similar age compositions (Fig. 6B, Tkble 

 4). One- and two-yr-old fish are the most numerous 

 in these three regions. Young-of-the-year and 3 yr- 

 olds are slightly less abundant than 1- and 2-yr-olds, 

 and there are fewer older fish in the samples. 



Baja California is characterized by a dominance 

 of young fish (Fig. 6C, Ikble 4). The age composi- 

 tions in the Ensenada, Cape San Quentin, and Sebas- 

 tian Viscaino Bay regions are very similar; young- 

 of-the-year and 1-yr-old fish are the most abundant, 

 and there is rapid decrease in the abundance of fish 

 with increasing age. Anchovies in southern Baja 

 California are principally from the southern stock. 

 The age composition in this region shows a pre- 



Table 3. — Significance levels for differences in growth of adult northern anchovies from different geographical 

 regions: Ensenada (E), Central California (CC), Cape San Quentin (CSQ), Coronado Escarpment (CE), Santa Barbara Chan- 

 nel (SBC), Tanner and Cortez Banks (TCB), Catalina Basin (CB), San Nicolas combined with Tanner and Cortez Banks (SN+TCB), 

 San Pedro Channel (SPC), San Nicolas (SN), Sebastian Viscaino Bay and Southern Baja California, central stock only (SVB+SB), 

 and Southern Baja California, southern stock only (S). Geographic areas are arranged in order from largest to smallest slopes. 



Age Composition by Area 



Geographical variation in age composition is one 

 factor which could influence the observed variation 

 in mean size of anchovies in the various regions; 

 therefore, age composition was calculated for each 

 of the regions used earlier (Fig. 2). Few anchovies 

 < 60 mm SL occur in the data, and it appears that 

 young-of-the-year fish are apparently not susceptible 

 to capture by the midwater trawl gear used in the 

 sea survey until they are about 6 mo old. 



Central California and the three offshore regions 

 within the Southern California Bight (San Nicolas, 



ponderance of 1-yr-olds, and like the other Baja 

 California regions there are few fish of age 4 or older. 



Age Composition by Depth Strata 



Anchovies primarily live within the upper mixed 

 layer; they occur in the surface layer over the con- 

 tinental shelf and over deepwater regions. Mais 

 (1974) showed that the average size of anchovies 

 sampled in offshore areas was greater than that of 

 anchovies sampled near the coast. The percentage 

 of trawl hauls containing anchovies was quite con- 

 stant in areas with different water depths, varying 



491 



