Population structure of striped marlin (Kajikia audax) in the Pacific Ocean based on analysis of microsatellite and mitochondrial DNA

Abstract

Genetic variation was surveyed at five microsatellite loci and the mitochondrial control region (819 bp) to test for the presence of genetic stock structure in striped marlin ( Kajikia audax ) collections taken from seven locations throughout the Pacific Ocean. Temporal replicates separated by 9 years were taken off Japan, and three temporal samples spanning 11 years were collected off the coast of eastern Australia. Analyses of multilocus microsatellite genotypes and mitochondrial control region sequences showed no significant heterogeneity among collections taken from the same location in different years; however, significant spatial genetic heterogeneity was observed across all samples for microsatellite markers (FST= 0.013, P < 0.001). Mitochondrial control region sequences were not different across all samples (ΦST= –0.01, P = 0.642). Analyses of molecular variance (AMOVA) revealed significant genetic differentiation between geographic regions for both microsatellite and mitochondrial markers. These results suggest the presence of genetically discrete populations within the Pacific Ocean and are supported by both the results of tagging studies, which show limited dispersal, and the presence of geographically separated spawning grounds.