Hildebrand used height of highest scale in the 

 curved portion of lateral line into head and 

 height of highest scale in the straight portion 

 of lateral line into head to separate the two 



species. Roedel and Fitch expressed scale 

 height as a percentage of head length. Data 

 fronn both as percentage of head length are 

 as follows: 



The greater range of Hildebrand' s Peru data 

 and Roedel and Fitchs' California data reflect 

 larger numbers of specimens. Otherwise it is 

 apparent that the largest scales in both the 

 curved and straight portions of the lateral 

 line of murphyi are about equal size; they are 

 about 60 percent larger than the largest scale 

 in the curved portion of the lateral line of 

 synnnnetricus and about 30 percent larger than 

 the largest scale in the straight portion. 



Roedel and Fitch, using all specimens of 

 Trachurus in the collections of the California 

 Academy of Science and Stanford University 

 stated: 



"On the basis of published descriptions 

 and comparisons with the specimens avail- 

 able to us, T. synnnnetricus appears to be 

 readily distinguishable from all other spe- 

 cies except the Atlantic T^. picturatus 

 (Bowdich). A direct comparison of material 

 will be necessary before the relationship 

 of these two can be determined." 



The differences between only symmetricus 

 and murphyi are discussed in their paper. 



1.22 Taxonomic status 



See above. 



1.23 Subspecies 

 See above. 



1.24 Standard common names, ver- 

 nacular names. 



The name sanctioned by the state of California 

 for purposes of record keeping is jack mack- 

 erel. Other names are: horse mackerel, Span- 

 ish mackerel, jackfish, saurel, agii, jurel, 

 macarella caballa. 



1.3 Morphology 



1.31 There seems to be very little 

 individual variation among jack mackerel, and 

 no geographic variation has been reported. 

 Clothier (1950) found that of 816 jack mackerel 



from Monterey Bay and Southern California, 

 813 (99.6 percent) had 24 vertebrae, one had 

 23, and two had 25. The species appears to 

 consist of a single population. 



As the fish increase in length it appear s that 

 the relative lengths of the pectoral fins in- 

 crease, and the last two rays in the dorsal 

 and anal fins become more finletlike in ap- 

 pearance. 



1.32 Cytomorphology 

 No data available. 



1.33 Protein specificity 

 No data. 



2 DISTRIBUTION 



2.1 Total area 



The population appears to have its maximum 

 density in California coastal waters (46.3) 

 between Point Conception, California, and 

 central Baja California. The range limits of 

 the population have not been determined fully 

 as noted below. Extensive egg and larva 

 surveys along the U.S. and Baja California 

 coasts indicate that the greatest amount of 

 jack mackerel spawning takes place between 

 Point Conception and Baja California between 

 80 to 240 miles offshore (Fig. 2). The seaward 

 extension of spawning has not been delimited 

 by the present surveys. Abundance of eggs and 

 larvae decreases to the south, and none are 

 taken off southern Baja California. Spawning 

 also occurs at least as far northas Washington 

 State, In August 1955, eggs and larvae were 

 taken on a special cruise (NORPAC) at stations 

 off the Oregon and Washington coasts to 150° 

 west longitude (or about 1/4 of the distance 

 from U.S. to Japan) which was as far as the 

 cruise extended (Ahlstrom, 1956). 



According to Fitch (1 956) adult jack mackerel 

 have been taken more than 600 miles off the 

 southern California coast and along the coast 

 from British Columbia to Cape San Lucas, Baja 

 California. Juveniles have been taken farther 



