CRAWFORD ET AL.: STOCK IDENTIFICATION OF WEAKFISH 



(i.e., Belford, NJ, the York River, VA and Cape Hat- 

 teras, NC) during the spring of 1982 and 1983. 



We collected juvenile fish in their natal estuaries 

 to minimize possible effects due to mixing after the 

 fish migrated. Fish were trawled in Delaware Bay, 

 NJ, Chesapeake Bay, VA, and Pamlico Sound, NC 

 from August to October 1981 and 1982. We mea- 

 sured fish to the nearest mm total length (TL) and 

 determined sex (when possible). Extracts of eye, 

 liver, and skeletal muscle tissue were separately 

 placed in centrifuge tubes and stored on dry ice. 

 When this was not possible, we froze whole fish on 

 ice and later removed the tissues in the laboratory. 

 All tissue samples were stored at -8°C until anal- 

 ysis (for electrophoretic details see Crawford 1984). 



Electromorph banding patterns were interpreted 

 based upon the protein's subunit structure and pre- 

 vious studies with homologous enzymes. (Utter et 

 al. 1974; Harris and Hopkinson 1976). We numbered 

 loci from the anode to the cathode in ascending 

 order. Allozymes were measured in millimeters 

 relative to the most common homomeric electro- 

 morph which was designated 100 and numbered ac- 

 cordingly. The bands exhibited v/ere consistent with 

 reported information on their molecular structure 

 (Manwell and Baker 1970). Allelic frequencies of 

 polymorphic systems were calculated and examined 

 for conformance to Hardy- Weinberg expectations 

 (HWE) using Levene's (1949) method for small sam- 

 ple sizes {N < 100). For polymorphic loci that had 

 null alleles the statistical procedures of (Speiss 1977) 

 were followed to test for HWE. Sampling localities 



were compared by using a chi-square contingency 

 test for haploid frequencies (Speiss 1977). We tested 

 juvenile and adult allelic frequencies of polymorphic 

 loci (excluding rare and null alleles) to determine 

 whether significant differences in gene frequencies 

 existed among 1) geographic location, 2) size/age 

 (i.e., adults vs. juveniles) groups, and 3) sexes. 

 Sampling locations were tested within regions, and 

 if there were no significant differences among sam- 

 pling locations, they were pooled. Pooled samples 

 were then compared with all other regions to deter- 

 mine if there were regional differences. We calcu- 

 lated (averaged over the polymorphic loci) the 

 genetic variation among the samples (F^i) (Hartl 

 1980). We obtained the percent polymorphic loci 

 (common allele (p) < 0.950) and genetic distances 

 (Nei 1972) using a BASIC computer program by 

 Green (1979). 



RESULTS 



Weakfish from four populations (Long Island 

 Sound, NY, Delaware Bay, NJ, York River, VA, and 

 Cape Hatteras, NC) were initially screened by starch 

 gel electrophoresis using 15 protein staining systems 

 (Table 1) to identify polymorphic loci and calculate 

 genetic distances. In samples obtained from other 

 collecting localities only the polymorphic loci were 

 evaluated. 



The activity of the 15 enzyme (protein) staining 

 systems was interpreted to reflect 25 structural loci 

 of which only two (8%) were polymorphic, 6-phos- 



Table 1.— Proteins and gel buffer-tissue combinations that provided the best 



resolution. 



'Enzyme Commission number 



I . Aminopropyl, pH 6.0 (Clayton and Tretiak 1972) 



II - Tris Citrate. pH 6,8 (Shaw and Prasad 1970), 



III - Tris Versane Borate, pH 8 (Shaw and Prasad 1970) 



IV - Ridgway, pH 8 5 (Ridgway et ai 1970) 



207 



