FISHERY BULLETIN: VOL. 74, NO. 3 



Table 2.— Food of northern anchovy larvae. 



Engraulis mordax (Berner 1959), of E. anchoita 

 (Ciechomski 1967), and E. ringens (Rojas de Men- 

 diola 1974). Berner and Rojas de Mendiola found 

 considerably more eggs than nauplii while Cie- 

 chomski reported about equal numbers. 



An unusual example of feeding by both anchovy 

 and sardine larvae was called to my attention by 

 Elbert H. Ahlstrom because of the obvious gorged 

 intestines of some of the larvae. This sample was 

 taken about 38 km off the coast of central Baja 

 California approximately 6 h after sunset and IV2 

 h after setting of a "first quarter" moon. Unusual 

 aspects of the sample were that most of the larger 

 larvae of the two species contained food at night 

 and that they were literally crammed with the 

 pteropod Limacina bulminoides. Of the larvae 

 over 10 mm in length, the 26 feeding sardines 

 averaged 24 pteropods per gut with a maximum of 

 54 in one 23-mm larva, and the 19 feeding an- 

 chovies averaged 18 per gut with a maximum of 26 

 in a 14-mm individual. Compared to the one or two 

 food particles usually found in a feeding anchovy 

 or sardine larva, the number of pteropods was 

 surprising. The only other molluscs found in either 

 sardine or anchovy larvae in this investigation 

 were two bivalve larvae, one each in two very 

 young anchovies. No molluscs were reported in the 

 extensive investigations of the food of anchovy 

 larvae by Berner (1959), Ciechomski (1967), or 

 Rojas de Mendiola (1974). It cannot be determined 

 whether the larvae found filled with Limacina 

 reflected beneficial feeding conditions where they 



were found, or a hazardous situation in which the 

 larvae had ingested material they could not digest 

 and void. 



Because the number of pteropods found in this 

 one sample is larger than the total number of food 

 particles found in the larger sardine and anchovy 

 larvae of all other samples examined, they were 

 not included in the overall tabulations for these 

 fish. The size of the pteropods was used to establish 

 the upper ingestible size of food particles for older 

 anchovies (Figure 3a). 



5 6 7 8 9 10 II 12 

 LENGTH OF LARVAE (mm) 



13 



4 8 12 16 20 24 28 32 

 LENGTH OF LARVAE (mm) 



Figure 3.-(a) Food size of northern anchovy larvae. The line is a 

 least square fit to all data points from 3 to 9 mm inclusive and is 

 expressed by the equation: S = 16.16L , where S is width of food 

 in microns and L is standard length of larvae in millimeters. The 

 correlation coefficient r is 0.473 and the coefficient of the 

 determination r- implies that 22% of the variation in food size 

 can be explained by larval size alone, (b) Food size of anchoveta 

 {Engraulis ringens) larvae. Adapted from Rojas de Mendiola 

 (1974). 



520 



