366 



Fishery Bulletin 91(2). 1993 



The intraspecific sequence variability of mtDNA of 

 S. aurita is comparable to that observed in most other 

 marine fishes. With a mean sequence divergence of 

 about p=0.51 (Nei & Li 1979), the mtDNAs of Spanish 

 sardines of the Gulf of Mexico fall within the range of 



mean values observed among other clupeids, i.e., be- 

 tween 0.37% for shad (Bentzen et al. 1989) and 2.4% 

 for menhaden (Avise et al. 1989). In both shad (Roff & 

 Bentzen 1989) and menhaden (Bowen & Avise 1990), 

 population-level mtDNA variability was observed 



