FISHERY BULLETIN: VOL. 87, NO. 3, 1989 



suggests that both larval populations had experi- 

 enced comparable feeding conditions. 



Although average daily mortality rates due to 

 starvation of first-feeding anchovy larvae were 

 higher at Site 1, 24%/d, than at Site 2, 12%/d 



Table 6. — Comparison of mortality coefficients (p) of norttiern 

 ancfiovy larvae (<20 days) between Site 1 and Site 2, using 

 analysis of covariance. P, is the larval production at age (; (is 

 age (d) from fertilization. Tfie values 3.05 and 3.23 are ages 

 at fiatching. 



Log-linear regressions of mortality are 



Site 1 ln(P,) = 4.49 - 3.90 [{ln(£/3.05))] 



Site 2 ln(P,) = 1 .4 - 3.05 [{\n{t/3.23))] 



Analysis of covariance between sites 



Sum of IVlean Prob, 



Source of variation df squares square F (tail) 



Equality of 



adjusted means 1 13.26 13.26 50.90 0.00 

 Zero slopes 

 All covariates 1 35.12 35.12 134.80 0.00 



error 11 2.87 0.26 



Equality of slopes 

 all covariates 

 and all groups 1 0.52 0.52 2.24 0.17 



error 



10 



2.34 



0.23 



(Table 7), the difference between sites was not 

 statistically significant (x" = 2.26; P > 0.15). 

 Incidence of starvation was low or nil after the 

 first-feeding stage at both sites. 



DISCUSSION 



We had expected to find higher rates of larval 

 northern anchovy growth and survival in the 

 inshore than in the offshore environment. Bias 

 or low precision cannot explain the similarity of 

 growth and mortality coefficients between sites. 

 The larval anchovy parameters might have been 

 biased had we sampled larval populations im- 

 ported from other sources by advection or dif- 

 fusion over the course of the measurement pe- 

 riods, but our time series of environmental 

 characteristics display no shifts to indicate 

 short-term change of properties or of popula- 

 tions at the drifters. Similarly, lack of precision 

 cannot be invoked: the number of tows and lar- 

 vae were sufficient to distinguish mortality coef- 

 ficients (P) differing by 0.5 with an 86% probabil- 

 ity (Lo et al. 1989). We must accept that the 

 mortahty coefficients were and that many more 

 similar tows would be necessary to distinguish 

 between them. 



14 



12 



E 



lO 



o 

 d 



< 



10 



i= 8h 

 O 



3 



a 

 o 



IE 

 Q. 



< 

 > 



a. 



< 



> 

 o 



6 - 



1 2 



(28.4, 3.05) 



Site 1 



N \ -Region 7 v 

  \ \^ \ 



■. \ 

 \ \ \^ /- All regions 



8 10 



AGE IN DAYS 



Figure 5.— Daily larval production vs. age for northern anchovy and fitted larval mortality curves for 

 Site 1 and Site 2, and for CalCOFI 8502 survey and subregions. Points are for Site 1 only. 



684 



