FISHERY BULLETIN VOL. 75, NO. 4 



Division in the Migration of Albacore 

 Into the American Fishery 



Our study indicates that there is a division in 

 the migration pattern of albacore into the Ameri- 

 can fishery with fish which compose the fishery off 

 the Pacific Northwest and off California following 

 different routes. We believe that the "northern" 

 branch of the migration progresses as described by 

 Powell et al. (1952) who, during an exploratory 

 albacore fishing survey over a region off the Pacific 

 Northwest, found albacore along a warm-water 

 edge that develops seasonally 400 to 500 n.mi. 

 offshore of southern Oregon in late June and early 

 July. The warmwater edge was observed to prog- 

 ress northward and coastward in a bulge or 

 pouchlike pattern as seasonal warming of the sur- 

 face waters took place over the ensuing weeks. The 

 occurrence of albacore was found to follow the 

 progression of the warmwater zone shoreward and 

 northward along the coasts of Oregon and 

 Washington and by mid- August to waters off the 

 Queen Charlotte Islands, British Columbia. Pow- 

 ell et al. (1952) concluded that these findings, as 

 well as earlier observations, indicated that the 

 main barrier directly or indirectly influencing the 

 distribution of albacore throughout their northern 

 range is water temperature. 



Clemens (1961) investigated the onset and 

 movements of the albacore fishery off California 

 and Baja California for the fishing seasons 1951 

 through 1953. From catch records he found that 

 albacore entered the coastal waters as far south as 

 200 n.mi. south of Guadalupe Island (lat. 29°N) in 

 some years and as far north as the San Juan Sea- 

 mount (lat. 33°N) in others. He also presented tag 

 recovery data which showed that albacore move 

 from Baja California or southern California in the 

 early season northward to central California as 

 the season progresses (however, only one recovery 

 of a tagged fish was made off northern California). 

 Clemens concluded that albacore entering the 

 American fishery initially migrate to Baja 

 California or southern California and that 

 longshore movement was the dominant mode of 

 their dispersal into coastal zones to the north. Al- 

 though he allowed that albacore may reach Ore- 

 gon and Washington waters by following the sea- 

 sonal bulge of warm offshore water as suggested 

 by Powell et al. ( 1952 ), Clemens stated that a large 

 part of the main body of albacore travel northward 

 up the coast to waters off the Pacific Northwest 

 from Baja California and southern California. No 



evidence was given for this statement and our 

 newer findings do not support it. We concur that 

 northward longshore movement is important in 

 nearshore waters, but conclude that fish entering 

 waters off Baja California or southern California 

 do not migrate farther north than about San Fran- 

 cisco before leaving the American fishery. 



Flittner (1963) presented a schematic diagram 

 of albacore movement off the Pacific coast based on 

 albacore catches made by U.S. Navy picket vessels 

 during 1960-62. The picket vessels, stationed 200 

 to 500 n.mi. offshore (no farther west than long. 

 135W) and spaced at latitudinal intervals of 300 

 n.mi., each trolled several jig lines from May 

 through October. Flittner said that albacore ap- 

 peared to congregate within an "optimum- 

 temperature" zone and seem to split into two mi- 

 gratory components. Early arrivals proceed to 

 southern feeding areas and late arrivals turn to 

 the northern area, each movement depending 

 upon the progression of seasonal warming. 



Progression of seasonal warming continues to 

 appear to be an important factor affecting paths of 

 albacore migration. However, influence of the 

 Transition Zone development and the division of 

 migration pattern described here add considerable 

 complexity to earlier ideas. Our findings suggest 

 that events in offshore waters are important in 

 determining the distribution and relative abun- 

 dance of albacore in coastal waters. 



Pacific Northwest and 

 California Groups of Fish 



Based on offshore- nearshore and north-south 

 geographic variations in size composition of alba- 

 core we postulate that the group of fish which 

 compose the albacore fishery off California are 

 separate from those which make up the fishery off 

 the Pacific Northwest. Brock (1943) arrived at a 

 similar conclusion after comparing length- 

 frequency distributions of albacore landed in Sap 

 Pedro, Calif., and Astoria, Oreg. Brock found dif- 

 ferences in size composition and stated, "This 

 would argue that the schools offish off the Oregon 

 coast were not a part of the schools appearing off 

 the California coast, even though, as indicated 

 above, the two groups may have had a common 

 origin. . . The time of arrival of fish and their 

 abundance as shown by the monthly commercial 

 catch for the ports discussed here (San Pedro and 

 Astoria) make it seem likely that at least two 

 separate groups of schools invaded the coastal 



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