eastern), off Tohoku Prefecture, and off Taiwan, deter- 

 mined that the size range was usually narrowest among 

 fish caught in October-November whereas it varied 

 widely among the fish caught in May-June (Fig. 40). 



Comparison of size data collected in Japan with those 

 from the Philippines shows that the former's commer- 

 cial catch constitutes smaller fish than the latter's. The 

 size of Auxis taken by the purse seiners Royal Venture 

 and Southward Ho in the Philippines, shown in Figure 

 41, ranged from about 25 to 55 cm with the majority of 

 the fish in the 40-4.5 cm range 



Data from the Indian Ocean show that the size of 

 Auxis in the commercial catch also varies widely. Silas 

 (1969) showed that A. thazard taken by drift net ranged 

 from about 20 to 51 cm, but a large proportion of the 



catch fell between 38 and 43 cm (Fig. 42). Silas also 

 showed that compared with A. thazard, A. rochei are 

 much smaller, ranging from about 19 to 29 cm and the 

 mode at about 20 to 21 cm. The purse seine apparently 

 catches Auxis of more uniform sizes. Figure 43 shows 

 that A. thazard caught by purse seine in Indian waters 

 had a relatively wide range from about 32 to 46 cm, but a 

 large proportion of the fish fell between 40 and 42 cm 

 (Silas 1969). 



Off Sri Lanka, A. rochei appearing in the commercial 

 catch are relatively small and their sizes vary from 16 to 

 34 cm; however, most are between 22 and 30 cm. Auxis 

 thazard, on the other hand, are much larger and range 

 from 20 to 58 cm, but a large proportion of them falls be- 

 tween 22 and 40 cm (Sivasubramaniam 1968). Separat- 



20 25 30 

 FORK LENGTH (cm) 



20 25 30 35 

 FORK LENGTH (cm) 



Figure 40. — Percentage 

 area of capture. 



frequency distribution of lengths of Auxis rochei, by date and 

 Japan (Hamada, Merita, Ishida, and Takezawa 197.3). 



44 



