GENETIC POPULATION-STRUCTURE OF THE SHORTFIN MAKO (ISURUS-OXYRINCHUS)INFERRED FROM RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM ANALYSIS OF MITOCHONDRIAL DMA

Restriction fragment length polymorphism analysis of mitochondrial DNA was used to investigate genetic population structure within the short fin mako (Isurus oxyrinchus). Tissue samples from 21-30 shortfin makos were collected from each of five locations, two within the North Atla ntic, one in the South Atlantic, one in the North Pacific, and one in the South Pacific. Mitochondrial DNA was digested with a panel of nine restriction enzymes to determine mitochondrial DNA haplotypes for eac h individual. Highly significant heterogeneity of haplotype distributi on was detected in the shortfin mako (chi(2) probability of equal hapl otype frequencies, p < 0.001). The pooled samples of North Atlantic sh ortfin mako appeared to be isolated from those from other oceans (p < 0.001). The nine restriction enzymes detected a haplotype diversity of 0.755 and a nucleotide sequence diversity of 0.347. There is no evide nce of multiple subspecies of shortfin mako, nor of any past genetic i solation between shortfin mako populations.