W-l 549XI0"'L' 



FORK LENGTH (cm) 



FORK LENGTH (cm) 



Figure 33. — Length-weight relationship of Aiuu rorhei caught in (A) Japanese waters (Yasui 1973) and in (B) Mediterranean waters (Rod- 



riguez-Roda 1%6). 



contents of molybdenum and nickel in the liver show no 

 relationship to sexual maturity, rate of growth, and area 

 of catch. 



The blood of Pacific A. rochei has been tested and 

 found to be relatively high in hemoglobin concentration 

 (Klawe et al. 1963). Barrett and Williams (1965) showed 

 that compared with other scombrids, the mean level 

 found for A. rochei was among the highest, reaching 19.2 

 g/100 ml and varying from 16.5 to 22.8 g/100 ml. Blood 

 smears of A. t hazard caught in Puerto Rican waters 

 showed a blood count of 1 large hemoblast, 1 small 

 hemoblast, 1 large lymphocyte, 30 small lymphocytes, 

 45 thrombocytes, and 22 granulocytes (neutrophils) 

 (Saunders 1966). Mature erythrocytes from A. thazard 

 blood averaged 10 /i in length and 7.5 n in width. 



3.5 Behavior 



3.51 Migrations and local movements 



Not much is known about the migration of Auxis in 

 the world's oceans. Most of what is known comes from 

 results of studies conducted in Japanese waters. Hotta 

 (1955), after examining the fluctuations in landings of 

 A. rochei along the coast of Japan in 1952, determined 

 their seasonal movement up and down the coast of 

 Japan. He observed that they occur in the Satsunan Sea 

 region and off Shikoku early in the year, but as the year 

 progresses, larger catches are made farther north and by 



June they are landed in the Izu Archipelago region (Fig. 

 35). The schools reach their most northern point around 

 Hokkaido in September, then move southward until in 

 December they appear to be concentrated mostly off the 

 Izu Archipelago and Shikoku. 



Detailed studies of long-distance movement of A. 

 rochei in Japanese waters showed that fish caught, tag- 

 ged, and released in August, September, and November 

 had a general tendency to move southward (Table 25, 

 Fig. .36). Yamashige (1974) determined from his tagging 

 studies that within the population of A. rochei off 

 Japan, differential migration occurs according to size. 

 The large influx of small fish into the fishery, as shown 

 by the length-frequency distribution (Fig. 37), is the 

 consequence of small fish moving south before the move- 

 ment of large fish begins. 



Short-distance movement of tagged A. rochei in 

 Japanese waters shows that they tend to move south- 

 ward late in the year although some northward move- 

 ment is also seen, but early in the year there is a definite 

 northward movement (Table 25) (Morita 1972; 

 Hamada, Ishida, Morita, Takezawa, Okabayashi, and 

 Ishii 1973; Hamada et al. 1974). 



3.52 Schooling 



The schooling instinct, according to a number of 

 sources, is very strong and orderly in Auxis. Jones (1963) 

 noted that the tendency of A. rochei to form large 



38 



