of independent spawning activity by that sub- 

 population of sardines (Harry 1949). The con- 

 sistent presence of O's, of course, would have 

 indicated that independent spawning had 

 occurred. 



Figure 1 presents the length-frequency dis- 

 tributions analyzed in this study. These anchovy 

 lengths were obtained from four exploratory 

 fishing surveys conducted from Cape Flattery, 

 Wash., to Yaquina Bay, Oreg., during 1966-67. 

 These surveys occasionally encountered schools 

 of anchovies containing small fish which became 

 gilled in the meshes of the survey gear (Figure 2). 

 It was speculated that these small anchovies 

 were the result of recent spawning activity in 

 the Washington-Oregon area. 



To analyze these length distributions, one 

 must first know the range of lengths associated 

 with individuals belonging to age-group 0. Clark 

 and Phillips ( 1952) indicated that 0-age anchovies 

 begin entering the southern California live-bait 

 fishery at lengths ranging from 5 to 9 cm. 

 Miller (1955) stated that 0-age fish begin enter- 

 ing the southern California commercial fishery 

 at 8.5-9.0 cm. Tillman (1972) concluded that 

 anchovies are at least 6 mo old when they 

 enter the commercially exploitable population at 



9 cm. Figure 3 presents the ranges, medians, 

 and median quartiles of the lengths of anchovy 

 larvae obtained by Richardson (1973). These 

 indicate that, in the northern subpopulation, 

 0-age anchovies approach 6 cm after 5 mo of 

 growth. Thus, a length range of 0-9 cm should 

 define those anchovies which resulted from 

 spawning, at least, during the past 6 mo. This 

 range was used to define the 0-age component 

 in all length-frequency distributions. 



Applying this criterion, the bar graphs of 

 Figure 1 indicate that 0-age anchovies indeed 

 were present in the northern subpopulation 

 during the years surveyed. Lengths less than 

 4 cm were not found, but the 4-9 cm range 

 composed, respectively, 11.6, 19.8, 87.0, and 

 39.0% of these four length-frequency distribu- 

 tions. The results shown for November-December 

 1966 and February 1967 are particularly striking, 

 having major modes located respectively at 6 

 and 5.5 cm. These latter two distributions result 

 from the facts that anchovies tend to school 

 by size and that the later 1966 and early 1967 

 surveys primarily encountered schools of small 

 fish. Therefore, following the rationale discussed 

 at the beginning of this section, the presence 

 of such juveniles would tend to confirm the 



20 



20 



10 



a. January 1966 N = I270 



tu 



b. April 1966 



N=4I9 



J 



m. 



8 10 12 14 16 18 

 LENGTH (cm) 



C.November -December 1966 N = 364 



V/A Juvenile 

 I I Adult 



d. February 1967 



N=4699 



^^^vy^ 



70 



8.5 10.0 11.5 130 

 LENGTH (0.5cm) 



TTTrT>. 



145 16.0 



Figure 1.— Composite length-frequency distributions of juvenile and adult northern anchovy sampled 



off Washington-Oregon during 1966-67. 



213 



