Abstract: A total of 77 giant Pacific octopus, Enteroctopus dofleini, tissue samples were
collected from the Oregon Coast (OR), Neah Bay Washington (NB), Puget Sound
Washington (PS) and the southeast coast of Vancouver Island, British Columbia, Canada
(BC) for genetic analyses. A suite of eight variable microsatellite markers developed from
giant Pacific octopuses were amplified in these samples to determine population diversity,
structure, relatedness and paternity. The majority of loci met Hardy-Weinberg equilibrium
expectations within each population. We found moderate genetic diversity (average observed
heterozygosity = 0.445, range = 0.307–0.515 and average expected heterozygosity = 0.567,
range = 0.506–0.696) and moderate population structuring with distinct separation of groups
(FST values ranged from 0.101 between BC and PS to 0.237 between BC and NB). Several
egg strings from the BC population were collected from three female octopus dens for
relatedness and paternity analyses. Results suggest strong support for multiple paternity
within one egg clutch with progeny sired by between two to four males.