Harbor porpoise in the North Pacific are found in coastal waters from southern California to Japan, but population structure is poorly known outside of a few local areas. We used multiplexed amplicon sequencing of 292 loci and genotyped clusters of single nucleotide polymoirphisms as microhaplotypes ( N = 271 samples) in addition to mitochondrial (mtDNA) sequence data ( N = 413 samples) to examine the genetic structure from sa...