Mitochondrial DNA variation in two samples of northern pike, Esox lucius L.

The mitochondrial genotype of northern pike, Esox lucius L., was characterized by restriction analysis performed over the entire mtDNA molecule (33 fish) and over a ∼1.4‐kb PCR‐amplified segment of a mitochondrial non‐coding control region (six fish). Out of eight restriction endonucleases used in the present study of the entire mitochondrial genome, the Nco I and Pst I enzymes produced variant fragment patterns which allowed identification of three mitochondrial genotypes. Low mtDNA diversity was shown by estimates of pairwise nucleotide substitution values ( d ; mean ± SE = 0.49 ± 0.43%), haplotype diversity ( h = 0.16) and the nucleotide diversity index (π= 0.06%). The present authors developed a PCR protocol for mitochondrial DNA non‐coding control region to search for more variation. Whereas the PCR assays revealed distinct length variation in this mtDNA segment, restriction analysis performed with three additional restriction enzymes showed no variability which could be attributed to a gain or loss of a particular restriction site. Although the mtDNA analysis proved ineffective in genetic discrimination between the two northern pike samples studied, fish with rare mtDNA genotypes could be used for conducting experimental genome engineering or stocking studies with this species.