Table 1. --Difference Betv/een populations of S. Japonic us (table 7 of Matsui, 1967) 



Four physical characteristics were selected 

 for detailed study. Three were related to the 

 initial position of vertebral structures: the 

 haemal arch, the haemal brace either single 

 or paired, and the paired haemal brace; and 

 the fourth to the head length relative to fork 

 length. 



Statistical analyses gave evidence of five 

 populations, each region, with the exception of 

 British Columbia and California, being sepa- 

 rable in some degree from adjoining regions. 

 Tag returns, however, demonstrated that a 

 portion of Vizcaino fish eventually reached 

 California waters. The Cape San Lucas ma- 

 terial differed radically in all respects from 

 the northern regions and was separable from 

 Gulf of California fish except in regard to the 

 initial position of the haemal arch. 



1.32 Cytomorphology 

 No data available. 



1.33 Protein specificity 

 No data available. 



2 DISTRIBUTION 



2. 1 Total area 



The Pacific mackerel in the northeast Pacific 

 Ocean has ranged from southeast Alaska 

 (Rounsefell and Dahlgren, 1934) to Banderas 

 Bay, Mexico (Fitch'). 



The natural regions ' of the oceans inhabited 

 by this mackerel thus included northwest 

 American coastal waters (4.2.4), SanFrancisco 

 waters (4.5.2), California waters (4.6.3), and 

 west Mexican waters (4.6.4). Now, as deter- 

 mined from populations of larvae, its range 

 may extend only as far north as Point Concep- 

 tion, Calif.,* south along the coast and into all 

 of the Gulf of California (Kramer, 1960), The 

 offshore extent of the population is as far as 

 200 nautical miles (370 km.) off northern 

 Baja California, and about 200 nautical miles 

 (370 km.) off central Baja California, with the 

 greatest numbers of larvae concentrated off 

 upper and central Baja California (fig. 2), 

 Data from two cruises in 1956 into the Gulf 

 of California by the CalCOFI (California 

 Cooperative Oceanic Fisheries Investigations) 

 in February (Ahlstrom, 1956) and April (un- 

 published) showed that the populations of 

 larvae in either of these months exceeded by 

 far the total population of larvae in 1956 in 

 the entire CalCOFI area for the whole year of 

 surveys on the outer coast. Furthermore, 

 although the CalCOFI data for the outer coast 

 showed that Pacific mackerel larvae extend 

 only as far south as Cape San Lucas, the data 



John E. Fitch, California Department of Fish and 

 Game, Terminal Island, Calif., by correspondence. 



For definition of these regions, see Rosa, H. Jr., 

 Preparation of synopses on the biology of species of living 

 aquatic organisms. Biology Branch, FAO Fisheries Divi- 

 sion. 



■• Recent reports of repeated traces of Pacific mackerel 

 with jack mackerel taken off Pt. Sur, Calif. — by corre- 

 spondence, Richard Parrish, California Department of Fish 

 and Game, Hopkins Marine Station, Pacific Grove, Calif. 



