For threatened and commercially important species, genetic and genomic tools promise accurate and cost-effective evaluations to contribute to effective conservation strategies and sustainable management (Ovenden et al., 2015; Willette et al., 2014). Genetics and genomic research on elasmobranchs has generally lagged behind studies involving bony sh and other taxa. But, with the increasing interest in elasmobranchs as an important food resource, the corresponding conservation concerns (Dulvy et al., 2017; Simpfendorfer and Dulvy, 2017) provide motivation to harness the power of genetics and genomics (Bernatchez et al., 2017). The earliest genetic studies on population structure in elasmobranchs investigated variants of enzymes coded

for by different alleles in nuclear genomes (allozymes) (e.g., Gardner and Ward, 1998; Smith, 1986). This transitioned into direct examination of the DNA sequence through the advent of the polymerase chain reaction (PCR) (Saiki et al., 1988) combined with nucleotide sequencing (Sanger et al., 1977a,b). These tools allowed elasmobranch researchers to focus on the maternally inherited, haploid mitochondrial DNA (mtDNA) genome. A shift back to the nuclear genome occurred when microsatellite loci were discovered (Powell et al., 1996).