most common among the fish species consumed. Among 

 31 preadult A. rochei (170-252 mm), fishes constituted 

 42'~f by volume and were found in 80% of the samples 

 (Fig. 31). Those that were important were Sardinella 

 spp., Anchouiella sp., Leiognathus sp., and carangids 

 (Table 22). Crustaceans were next in importance ac- 

 counting for 24% by volume and found in 77% of the 

 samples. Rabindra Nath (1962) reported that among the 

 most common crustaceans consumed hy Auxis in Indian 

 waters were Rhopolophthalmus sp., Hyperia 

 bengalensis, Oxycephalus clausi, Pseudophausia lati- 

 frons, Acetes erythreus, and Squilla larvae. 

 Cephalopods formed 22% of the food consumed 

 (Kumaran 1964), but pteropods were relatively unim- 

 portant in the diet (Rabindra Nath 1962). Kumaran 

 (1964) also noted that larval stomatofX)ds and Lucifer 

 constituted a major portion of the diet of some 

 specimens captured near Quilandy on the west coast of 

 India. Other items of food occasionally seen were 

 chaetognaths, Halobates, and polychaetes. 



-List of food items of preadult specimens of Auxu rochei 

 from the Indian Ocean (Kumaran 1964). 



Figure 31. — Percentages, by volume, of the types of food con- 

 sumed by preadult specimens of Auxis rochei in the Indian Ocean 

 (Kumaran 1964). 



3.43 Growth rate 



Observations on jKjstlarval growth indicate that cap- 

 tive Auxis grow faster than Euthynnus lineatus 

 (Clemens 1956). Of five postlarval Auxis placed in an 

 aquarium for observation, three died several hours later 

 from injuries received in handling. Of the two remaining 

 Auxis, one measuring 20 mm TL grew to 40 mm in 6 

 days; the larger 30 mm specimen reached 46 mm during 

 the same period. 



The rate of growth of A. rochei estimated from modal 

 progression of length-frequency data appears to be 

 rather slow compared to that observed in larvae that 

 were hatched from artificially fertilized eggs. Hotta 



(1955), who used monthly length-frequency histograms 

 to estimate the growth of A. rochei caught in the north- 

 eastern sea off the Pacific coast of Japan, constructed a 

 growth curve depicting body lengths at ages O-FV. From 

 the curve, shown in Figure 32, it appears that A. rochei 

 reach about 17 cm 1 yr after hatching. But Harada, 

 Murata, and Furutani (1973) observed that larvae of A. 

 rochei under the best condition grew to 15.7 cm in 52 

 days (Fig. 21). 



In addition to growth rates, the condition factor has 

 been calculated for A. t hazard. The condition factor 

 (K), which expresses the relative well-being of the fish, 



/ 



o SATSUNAN 



• SHIKOKU 



• IZU ARCHIPELAGO 

 « TOHOKU 



Figure 32. — Growth curve of Auxit rochei based on specimens 

 from four localities in Japan (Hotta 1955). 



36 



