FISHERY BULLETIN: VOL. 75, NO. 4 



150° 145° 



48° | 1 1 1 1 1 — 



45' 



140° 



4'. ' 



35° 



30 c 



25' 



i — l — I — r 



_i i i i_ 



j I i i i 



I 1 25 ° 



150° 



145° 



140° 



135° 



130° 



125° 



120° 



115° 



FIGURE 11.— Recoveries made during the same season as release offish tagged during the early-season 



surveys in: a. 1972; b. 1973; and c. 1974. 



when almost all of the recoveries offish tagged in 

 1974 were made in waters off the Pacific North- 

 west (Figure lie). 



Differences in recovery pattern cannot be ac- 

 counted for by geographic variations in fishing 

 effort and fish catch. In all 3 yr, 70% or more of the 

 fish caught during the commercial fishery was off 

 the Pacific Northwest. It appears, instead, that 

 differences in recovery patterns could be related to 

 the location where tagged fish were released. In 

 both 1972 and 1973, most of the tagging effort in 

 offshore waters was between lat. 33° and 34°N and 

 in 1974 it was farther north, between lat. 35° and 

 36°N. The different and divergent patterns appar- 

 ently are the result of the albacore following dif- 

 ferent and divergent migration routes toward the 

 nearshore waters. Tagging efforts of 1972 and 

 1973 and those of 1974 were apparently concen- 

 trated upon different branches of the migration. 

 The division in the migration pattern appears to 

 have occurred near lat. 35°N and must have occur- 

 red west of, and prior to, the appearance of the fish 

 in the survey region. 



Support for this proposed division in the migra- 

 tion pattern of albacore is indicated by differences 

 in length-frequency distribution of albacore 

 caught in the commercial fishery off California 

 and north of California. Differences in size com- 

 position offish caught in 1972 in the two regions 

 (Figure 12 upper and lower) include: 1) the mode of 

 large-size fish was about 5 cm larger in fish caught 

 off California than in fish caught off the Pacific 

 Northwest; 2) the mode of the medium-size fish, 

 which formed the dominant size group in both 

 regions, was 1 to 2 cm larger in fish caught off 

 California than in fish caught off the Pacific 

 Northwest; and 3) occurrence of three modal size 

 groups taken in the fishery off California, but only 

 two off the Pacific Northwest, where the smallest 

 modal size group was absent. Examination of 

 size-frequency distributions for 1973 and 1974 

 yielded similar results. 



The size composition of albacore caught west of 

 long. 130°W by charter vessels in 1972 (Figure 12 

 lower) was very similar to that for fish taken in the 

 commercial fishery off California (Figure 12 mid- 



814 



