absent in Hy. melanochir. The fourth specimen 

 is intermediate with a faint rostral groove. 



Vertebral counts also indicate hybridization. 

 The small Hy. melanochir had 60 vertebrae, at 

 the high end of the range for nine Victorian 

 specimens (Table 1) . The two Hy. australis had 

 57 and 58 vertebrae, comparing well with 50 New 

 South Wales specimens. The fourth specimen 

 was intermediate with 59 vertebrae. 



Based on its intermediacy in gill-raker and 

 vertebral counts, pigmentation, upper jaw 

 length, and otolith structure, I co_nclude that the 

 fourth specimen is a hybrid between Hy. au- 

 stralis and Hy. melanochir. The two species are 

 essentially allopatric and show character dis- 

 placement as their ranges approach, that is, the 

 Victoria population of Hy. melanochir differs 

 more from the neighboring New South Wales 

 population of Hy. aiistralis than do populations 

 of Hy. melanochir from further west, in South 

 Australia and Western Australia (Collette, see 

 footnote 1). 



I thank Daniel M. Cohen and Robert H. Gibbs, 

 Jr., for reviewing the manuscript, John E. Fitch 

 for examining the otoliths, Frank J. Schwartz 

 for checking his manuscript on fish hybrids, R. 

 Budd for permitting access to the Sydney fish 

 market, and Keiko Moore for preparing the il- 

 lustrations. 



Literature Cited 



Schwartz, F. J. 



1972. World literature to fish hybrids with an 

 analysis by family, species, and hybrid. Publ. 

 Gulf Coast Res. Lab. Mus. 3, 328 p. 



Bruce B. Collette 



Systematics Laboratory 



National Marine Fisheries Service, NOAA 



U.S. National Museum 



Washington, B.C. 20560 



CONTRIBUTION ON THE SPAWNING OF 



AUXIS SP. (PISCES, SCOMBRIDAE) IN 



THE ATLANTIC OCEAN 



The frigate mackerel (Auxis sp.) are apparently 

 among the most abundant scombrids in the trop- 

 ical Atlantic Ocean. They form a substantial 

 part of the diet of skipjack tuna, Katsuivonus 

 pelamis; yellowfin tuna, Thunnus albacares 

 (Dragovich, 1970a); and bluefin tuna, T. thyn- 

 nus (Dragovich, 1970b); and, therefore, it is 

 important to understand their life history and 

 their role in the trophodynamics of tropical 

 ocean ecosystems. We report on the examina- 

 tion of ovaries from 76 frigate mackerel collect- 

 ed from the eastern and western tropical Atlan- 

 tic, and off Cape Hatteras, N.C. (Figure 1). 



60°W 



60° W 



Figure 1. — Location and number of Auxis sp. captured 

 (in circle) from which ovaries were examined. 



The genus Auxis may be composed of two spe- 

 cies, A. thazard (Lacepede) and A. rochei (Ris- 

 so). We were not able to assign the specimens 

 in our study to either species because the pub- 

 lished diagnostic characters were not reliable for 

 species identification. More taxonomic work is 

 needed on the genus (William J. Richards, 

 Southeast Fisheries Center, Miami Laboratory, 



' Contribution No. 222, Southeast Fisheries Center, 

 Miami Laboratory, National Marine Fisheries Service. 



321 



