FISHERY BULLETIN: VOL. 78, NO. 3 



of 21 northern anchovies. Functional (geometric 

 mean) regressions (Ricker 1973) were used to 

 examine relationships between total fecundity 

 and body weight (grams), standard length (mil- 

 limeters), and ovary weight (grams). These re- 

 gression equations can also be used for prediction 

 of fecundity from body weight and standard 

 length. The standard error of each (geometric 

 mean) regression coefficient was obtained by tak- 

 ing the square root of the variance as calculated 

 from Ricker (1973). Ricker also gave procedures to 

 transform functional parameters to predictive if 

 this is desired. 



Photomicrographs of oocytes in various stages of 

 development were taken at magnifications of 12.5, 

 21, or 25 X through a dissecting microscope using 

 transmitted light. 



RESULTS 



Length and Age at Sexual Maturity 



Estimates of the size when northern anchovies 

 reach sexual maturity were determined from ob- 

 servations of gonads from frozen fish collected in 

 May (991 fish) and July (263 fish) 1975. Estimates 

 of age were based on counts of annuli, the interface 

 between an inner hyaline and outer opaque zone, 

 on otoliths (Collins and Spratt 1969; Spratt 1975) 

 but only data on ages I and II fish are reported 

 here. Otoliths of anchovies collected in May and 

 July with either a hyaline margin but no com- 

 pleted annulus or an annulus at the margin were 

 considered to be age I. Northern anchovies from 

 May and July with one completed annulus on their 

 otoliths and a hyaline margin were considered to 

 be age II. 



All fish, <85 mm SL, taken in May (376) were 

 immature. Both mature and immature fish were 



found within the size range 85-128 mm SL. Of 79 

 fish between 85 and 100 mm SL, 69% were imma- 

 ture and 31% were mature. Of 205 fish between 101 

 and 120 mm SL, only 5% were immature and 95% 

 were mature. Only 3 out of 147 fish between 120 

 and 128 mm were immature and all fish >128 mm 

 SL were mature. 



Of 183 age I fish taken in May and measuring 

 55-99 mm SL (x = 75 mm SL) only 5 males, 84-96 

 mm SL, appeared to be mature. Yet of 263 age I 

 fish measuring 56-94 mm SL ix = 76 mm SL), 

 collected in July during the spawning season, 

 none were mature. Possibly gametes begin to de- 

 velop in adolescent northern anchovies early in 

 the season but then do not reach the final stages of 

 maturation required for spawning. Hickling 

 (1930, 1935) reported this phenomenon in adoles- 

 cent hake, Merluccius merluccius, from the North 

 Atlantic. Of 14 age II northern anchovies from 

 May (sex was not recorded), 7 were immature and 

 7 were mature. The smallest northern anchovies 

 observed in spawning condition in July were 104 

 mm SL (male) and 107 mm SL (female). Ages are 

 not available for these fish. This evidence indi- 

 cates attainment of sexual maturity in some 

 northern anchovies by age II. 



Gonadal Condition 



General gonadal development was measured in 

 both immature and mature northern anchovies by 

 mean monthly gonadal indices (Table 3). Mean 

 GFs of immature males between 86 and 100 mm SL 

 and females between 96 and 100 mm SL increased 

 between March and May indicating some gonadal 

 growth and differentiation. By July GI's in these 

 size groups were lower than in May indicating no 

 further gonadal development had occurred. Mean 

 GI's of mature fish, >101 mm SL, increased from 



Table 3. — Mean gonadal indices (GI) by month for male (M) and female (F) Engraulis mordax in different size (standard length) 



intervals (N = no. offish). 



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