FISHERY BULLETIN: VOL. 85, NO. 3 



exploited herring stocks could differ dramatically 

 depending upon which alternative is correct 

 (MacLean and Evans 1981). 



Restriction endonuclease analysis of mitochon- 

 drial DNA (mtDNA) has, in recent years, 

 uncovered substantial genetic variation in natu- 

 ral populations (Brown 1983). The technique is 

 potentially much more sensitive than conven- 

 tional allozyme analysis for characterizing popu- 

 lation structure and has been successfully ex- 

 ploited to discriminate groups not detectable with 

 allozymes (e.g., Avise et al. 1986; R. W. Chapman 

 unpubl. data). To further examine genetic rela- 

 tionships among herring stocks, restrictive en- 

 zyme digestion patterns of mtDNA were exam- 

 ined in individuals from three spawning localities 

 in the northwestern Atlantic. 



MATERIAL AND METHODS 



Samples of fall spawning Atlantic herring were 



obtained from two discrete localities in the Gulf of 

 Maine: Jeffries Ledge, MA (lat. 42°50'N, long. 

 66°30'W; 9 September 1984) and Trinity Ledge, 

 NB, Canada (lat. 45°20'N, long. 65°30'W, Sep- 

 tember 1984; 30 August 1985). A sample of spring 

 spawning Atlantic herring was collected from off 

 Pt. Escuminac, Gulf of St. Lawrence, NB (lat. 

 47°01'N, long. 64°40'W; 12 May 1985) (Fig. 1). All 

 Atlantic herring were collected during peak re- 

 production. Samples were frozen in the field and 

 stored at — 80°C for up to 6 months prior to anal- 

 ysis. 



Lansman et al. (1981) provided a useful review 

 of the application of mtDNA to population stud- 

 ies. mtDNA was prepared from egg tissue (11-15 

 g/female) by the rapid phenol extraction proce- 

 dure of Chapman and Powers (1984). After the 

 final chloroform extraction, mtDNA in the 

 aqueous phase was precipitated in 95% ethanol in 

 the presence of 3 M sodium acetate, dried under 

 vacuum and dissolved in 10 mM Tris, pH 7.5. 



Figure 1. — Collection localities for Atlantic herring. 

 (1) Jeffries Ledge, MA; (2) Trinity Ledge, NB; (3) Point 

 Escuminac (St. Lawrence), NB. 



