Figure 1. — Trachurus symmetrlcus (Ayres) (Drawing by George Mattson USFWS). 



The genus Trachurus may be separated 

 from the other genera of the subfamily Car- 

 anginae by the lateral line scutes which are 

 present along the entire lateral line in 

 Trachurus and either absent or confined to 

 the posterior part of the body in the other 

 genera. 



Roedel and Fitch (1952) gave the following 

 diagnosis of Trachurus symmetricus based on 

 1,100 specimens ranging in standard length 

 from 93 to 557 mm. and collected from Oregon 

 to central Baja California: "On the basis of 

 these 1,100 fish, we conclude that in T. 

 symmetricus , the accessory lateral line usually 

 extends to the insertion of the second dorsal 

 fin. It may end as far forward as the fourth 

 dorsal spine or as far posterior as the fifth 

 dorsal soft ray. All scales in the lateral line 

 are enlarged. The lateral line is curved 

 abruptly downward about under the insertion 

 of the second dorsal and becomes straight 

 under the eighth to eleventh dorsal ray. The 

 length of the chord of the curved portion is 

 usually, but not always, greater than the 

 length of the straight portion. Scales number 

 52(41-59) in the curved portion and 46 (40-55) 

 in the straight; total scales are 99(87-111). 

 Other counts are: gill rakers 15 (13-18) + 

 41 (37-45) = 56 (51-61); gill teeth 7 (5-9) + 

 27 (25-30) = 34 (31-39); first dorsal fin, VIII; 

 second dorsal I, 33(28-38); analll-I, 29 (22-33). 

 The last dorsal and the last anal rays become 

 progressively more finletlike in structure as 

 the fish grows and in large individuals appear 

 to be detached finlets. However, a very fine 

 membrane or its remnants can usually be 

 detected in carefully handled individuals." 



Most earlier authors tended to place the 

 various geographic populations of Trachurus 



into two species, T. trachurus (L.) and T. 

 picturatus (Bowdich), with T^- symmetricus 

 in the latter. In 1920 Nichols described the 

 Peruvian fornn as T\ murphyi and included a 

 key to the species of Trachurus . Hildebrand 

 (1946) was unable to separate T. symmetricus 

 and T\ nnurphyi using Nichol's key, but could 

 distinguish them on the basis of gill rakers 

 on the lower limb of the first arch and depth 

 of scutes. Roedel and Fitch (1952) also used 

 height of scutes and, in addition, relative 

 p ectoral fin length to separate the two 

 species. 



Hildebrand found that seven specimens of 

 murphyi 485 to 497 mnn. standard length had 

 45-48 gill rakers on the lower arch and six 

 specimens of symmetricus of undetermined 

 length had 40-42. Roedel and Fitch gave 37 

 to 45 as the range for 1,100 symmetricus 93 

 to 557 mm. long. No data are given for their 

 two specimens of murphyi. 



Roedel and Fitch found that pectoral length 

 was contained 3.2 times in standard length 

 in two murphyi 275 and 323 mm.and 3.6 to 4.5 

 times in 200 symmetricus 250 to 350 mm. Al- 

 though not stated by Hildebrand, his pectoral- 

 in-length measurements appear to be based on 

 total length. On the basis of standard length 

 his measurements would be approximately 3.0 

 to 3.5 for an unstated number of small murphyi 

 60-117 mm. and 4.3 to 4.6 for seven large 

 specimens 485-497 mm. The data on pectoral- 

 in-head given by Walford and Meyers (1944) 

 for five large specimens of synnmetricus 380 

 to 510 mm. ranged from 4.2 to 4.9. Apparently 

 as in other Carangids (Berry, 1959), the pec- 

 toral length increases at a relatively greater 

 rate with growth than does body length. 



