FISHERY BULLETIN: VOL. 75. NO. 3 



Sardines spawn near the Mecynocera boundary, 

 inshore of the jack mackerel and mostly offshore 

 of anchovy (Anonymous 1953:22), but, also, more 

 southerly of the other two. Sardine larvae combine 

 some feeding characteristics of jack mackerel and 

 anchovy larvae. Food particle size of sardine lar- 

 vae increases isometrically with length of larvae 

 as in jack mackerel but is smaller for unit larval 

 length and is composed more of copepod eggs and 

 nauplii as in anchovy larvae. 



Microcopepod Densities Influence 

 Larval Fish Survival 



Other investigations in the CalCOFI area, and 

 in similar latitudes in Japanese waters, helped 

 to approximate the biomass spectrum of the 

 naupliar population. Beers and Stewart (1967) 

 estimated numbers of various microzooplankton 

 at five locations across the California Current. 

 Samples were taken by pumping water through 

 several sizes of niters from depths ranging from 

 the surface to 105 m. Their values for copepod 

 nauplii, averaged and integrated, are compared 

 with the values reported herein as follows: 



Q +2.00 



UJ 



z 

 < 



H 

 UJ 



cr 



Zj 



cr 



UJ 



cr 



UJ 

 CD 



< 



to 



z> 



u. 

 o 



X 

 H 



cr 

 < 



O 



-1.00 — 



-2.00 







50 100 



MESH SIZE (jjm) 



150 



FIGURE 9. — Logarithms of the usual densities of various sizes 

 of nauplii in relation to mesh size. The line is a least square 

 fit to all data points combined from the equation N = -0.0188w 

 + 1.3370. 



Nauplii/ 



Mesh size liter Logrithm 



Total no., all sizes 22.078 1.3440 



Retained by 35 fim 3.878 0.5886 



Retained by 56 /xm 2.884 0.4600 



Retained by 103 /xm 0.198 -0.7033 



Retained by 120 /*m 0.095 -1.0223 



Retained by 143 /xm 0.058 -1.2366 



Source 

 Beers and Stewart 

 Beers and Stewart 

 This report 

 Beers and Stewart 

 This report 

 This report 



Beers and Stewart 



N = -0.01976u; + 1.31857 



r = 0.9994, r 



This report 



2 - 



0.9988. 



N = -0.02029u> + 1.5577 

 r = 0.9900, r 2 = 0.9801. 



(2) 



(3) 



Logarithms of the above, plotted in Figure 9, 

 are highly correlated with mesh size for the two 

 individual sets of data as well as when they are 

 combined. The line in Figure 9 is a least square 

 fit to all data points combined and is expressed as: 



N = -0.0188u; + 1.3370 

 (intercept at size 0) 



(1) 



where N is concentration of nauplii (number per 

 liter) and w is mesh aperture size. The correlation 

 coefficient, r, is 0.9931 and the coefficient of de- 

 termination, r 2 , implies that 98.62% of the varia- 

 tion of naupliar concentrations can be explained 

 by mesh size alone. 



Least square fits for the two individual sets of 

 data are as follows: 



The microcopepod assemblage in onshore water 

 off the southern California-northern Baja Cali- 

 fornia coast is strikingly similar to that in coastal 

 waters at the same latitudes on the other side of 

 the Pacific. Yokota et al. (1961) measured widths 

 and lengths of 8,839 copepod nauplii and 1,389 

 copepodids from 666 samples captured in 1-liter 

 containers from an area off the southeast coast 

 of Kyushu over a 2-yr period. Average widths and 

 lengths of nauplii were 67.7 and 156.1 /xm, respec- 

 tively, with a length to width ratio of 2.306. 

 Assuming a cylindrical form, the average Kyushu 

 nauplius has a volume of about 562,000 /j.m 3 

 which differs by only about 10% from the 

 510,000 tim 3 volume of the average La Jolla nau- 

 plius (Beers and Stewart 1970). Concentrations 

 ranged from to 524 nauplii/liter (only two 

 samples were greater than 100/liter) with an 



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