BAILEY: DESCRIPTION AND SURFACE DISTRIBUTION OF JACK MACKEREL 



Table 3— Comparison of meristic and morphometric characters of Trachurus murphyi (numbers sfiown are range and 



mean). 



'See text page 274 regarding abbreviations. 



2|ncluded in these counts is the first spine of the second dorsal fin and anal fin. 



pletely formed in the juveniles, for example, 

 Santander and de Castillo (1971) noted that fin for- 

 mation was complete in T. murphyi of 13 mm SL. 

 In other Trachurus species lateral line scales and 

 scutes are well developed by 35 mm (Ahlstrom and 

 Ball 1954; Haigh 1972; Stephenson and Robertson 

 1977). 



There are significant differences in the numbers 

 of scales and scutes along the curved and straight 

 sections of the lateral line between the present spe- 

 cimens and those described by Berry and Cohen 

 (1974) (Student's t test, P < 0.05, df = 51), Sha- 

 boneyev and Kotlyar (1979) {Z test, P < 0.05), and 

 Kotlyar (1976) (Z test, P < 0.05). These differences 

 may be due to how the dividing line between the two 

 sections is defined. When the curved and straight 

 sections are combined into single counts along the 

 entire lateral line, the present specimens only dif- 

 fer significantly from those of Berry and Cohen 

 (1974). 



Evseenko (1987) suggested that Trachurus mur- 

 phyi has a spawning area centered on the Sub- 

 tropical Convergence Zone extending from Chile to 

 between 150°W and 160°W. He based his sugges- 

 tion on an average transport figure for the area, 

 growth data of T. symmetricus and the occurrence 

 of one juvenile and two larvae in the central South 

 Pacific. Results from the present study verifies his 

 suggestion in the central South Pacific and, by using 

 a similar approach, extends the probable spawning 

 area westward to include the Chatham Rise. 



It is apparent that Trachurus murphyi is found 

 and likely to spawn across the South Pacific from 

 New Zealand to Chile. The abundance of juveniles 

 in the Subtropical Convergence Zone between 

 127°W and 165°W further suggests that a large 

 commercial resource may exist in the central and 

 western parts of the South Pacific. 



ACKNOWLEDGMENTS 



I thank W. Smith-Vaniz for confirming the iden- 

 tification of Trachurus murphyi. The assistance of 

 the captains and crew of RV's Townsend Cromwell, 

 Coriolis, and Kaharoa as well as scientific person- 

 nel from the National Marine Fisheries Service 

 laboratories in Honolulu, HI and La JoUa, CA and 

 the Noumea, New Caledonia Centre of the Office 

 de Recherche Scientifique et Technique Otre-Mer 

 is gratefully acknowledged. Thanks are also due to 

 J. A. Wetheral, T. E. Murray, J. B. Jones, R. M. 

 Laurs, P. J. McMillan, B. B. Collette, and an anony- 

 mous reviewer for criticism of the manuscript. 



LITERATURE CITED 



Ahlstrom, E. H., and 0. P. Ball. 



1954. Description of eggs and larvae of jack mackerel [Tra- 

 churus symmetricus) and distribution and abundance of 

 larvae in 1950 and 1951. U.S. Fish Wildl. Serv., Fish. Bull. 

 56:209-245. 

 Berry. F. H. 



1968. A new species of carangid fish (Decapturas tabl ) from 



277 



