increases with age because older fish tend to gain pro- 

 portionately more in weight than in length. The formula 

 for K is 



K = 



aW 

 L3 



in which a = constant 



W = weight in grams 



L = standard length in millimeters (Rounse- 

 fell and Everhart 1953). 



At La Linea, Spain, the average values of the condi- 

 tion factor for each length group of A. rochei were usual- 

 ly larger for males than for females (Rodriguez-Roda 

 1966). Furthermore, the values of X decreased from May 

 to August, but increased in September which coincided 

 with the spawning period. Comparison of K among the 

 size groups showed no significant differences. 



Ishida (1971), who also calculated condition factor of 

 Auxis caught off Japan, found that of the two species, A. 

 thazard caught at Mikomoto and Shionomisaki had 

 higher indices than A. rochei. Between areas, however, 

 there appeared to be no appreciable difference. 



The length-weight relationship has been described for 

 A. thazard and A. rochei caught in the world's oceans. 

 The expression for the relationship is 



W = af 



in which W = weight in grams 



L = length in centimeters 

 a and b = constants. 



Table 23 gives the constant for the expression of the 

 predictive length-weight relationship calculated by 

 Ishida (1971) for both species of Auxis and by Yasui 

 (1975) for A. rochei caught in Japanese waters, by 

 Lenarz (1974) for A. rochei captured in the Atlantic 

 Ocean, by Rodriguez-Roda (1966) for A. rochei caught in 

 Spanish waters near the Strait of Gibraltar, and by 

 Sivasubramaniam (1966) for both species caught around 

 Sri Lanka in the Indian Ocean. Figure 33 depicts the 

 length-weight curves constructed by Rodriguez-Roda 

 (1966) and Yasui (1975). For A. rochei caught in Spanish 

 waters, Rodriguez-Roda has also provided the average 



and calculated weights for the length groups studied 

 (Table 24). 



The maximum size reported is 66 cm for A. rochei in 

 the eastern Atlantic Ocean (Collignon see footnote 2). 



Table 24. — Length groups, average weights, and calculated average 

 weights of Auxis rochei caught at Barbate, Tarifa, and La Linea, 

 Spain, in 1958, 1961, 1963, and 1974 combined (Rodriguez-Roda 1966). 



3.44 Metabolism 



In A. rochei, a correlation has been found between 

 sexual maturity and the amount of iron, copper, and 

 zinc in various body tissues (Suzuki and Mono 1957). 

 Suzuki and Morio showed that in the liver, the iron con- 

 tent decreases progressively with maturation, is at a 

 minimum when the gonads become ripe and then in- 

 creases significantly when the gonads are spent (Fig. 

 34a). The contents of copjjer and zinc show a similar 

 tendency to decrease with maturation but minimums 

 are reached at a stage when egg formation is still con- 

 tinuing in the ovaries (Fig. 34b, c). Suzuki and Morio 

 also observed a negative correlation between the fat con- 

 tent of the liver and the amount of iron and copper (Fig. 

 34d). The relationship, however, is not consistent; it 

 tends to break down in fish that have gonads approach- 

 ing the ripe stage. Concerning molybdenum and nickel 

 in the tissues of A. rochei, Morio and Suzuki (1959) 

 determined that the former occurs in highest concen- 

 tration in the liver whereas the latter shows up highest 

 in the pyloric caeca. Further analysis indicated that the 



Table 23.— Constants calculated by various investigators for the expression of the predictive length-weight 

 relationship of Auxig thazard and A. rochei. 



37 



