FISHERY BULLETIN: VOL. 70. NO. 3 



WOO 



o Murphy a Clutter 



• Tester 



ft Atilstrom 



6.0 7.0 8.0 9.0 10.0 1.0 



Standard Length ( mm ) 



Figure 2. — Anchovy larvae catches reported by Ahlstrom 

 (1965) on Engraulis, Tester (1951) on Stolephoriis, and 

 Murphy and Clutter (present paper) on Stolephorus. 

 The lines are least square regressions. 



RESULTS 



DAY SAMPLES 



As indicated earlier, the bulk of the sampling 

 was done in the daytime. We used a meter plank- 

 ton net as our measure of normal sampling effi- 

 ciency. Because of this, it is of considerable 

 interest to establish how the sampling efficiency 

 of our meter net system compared with the ex- 

 perience of other investigators using the same 

 equipment and towing speeds. This was done 

 by comparing the slopes of our anchovy size-fre- 

 quency curve with the results of an earlier study 

 in Kaneohe Bay (Tester, 1951) and with the re- 



sults of a massive program in the eastern Pa- 

 cific on the northern anchovy {Engraulis mor- 

 dax) (Ahlstrom, 1965). 



The results of the three programs (Figure 2) 

 are remarkably similar, and although the En- 

 graulis data have a somewhat flatter slope, the 

 difference is not significant, at least for the pre- 

 sent purpose. This was not entirely unexpected 

 since the eggs and larvae of Stolephonis are al- 

 most identical in size and appearance to those of 

 Engraulis. We assume that our comparison of 

 purse seine and plankton net catches of anchovy 

 larvae is applicable to all anchovy larvae. 



Our day purse seine and meter net data are 

 compared in Figure 3 and Table 1. They indi- 

 cate remarkable undersampling by the meter net. 

 The break in the slope at 20 mm in the purse 

 seine curve coincides approximately with the 

 transformation from larva to juvenile. This may 



I I I I I I I I I I I I I I I I 1 I I I I I I I I I I I I I I I I i_ 



Purse Seine 

 Plankton Net 



.I'-i- 







I'll 



I I 



to 295mm 



I 1 I I I I I I I I I I I I I I I I I I I I 



10 15 20 25 



Standard Length ( mm ) 



Figure 3. — Day catches of the purse seine and plankton 



net. 



792 



