The polychaete bloodworm, Glycera dibranchiata Ehlers, 1868 is an important source of bait for saltwater fishing and is harvested from mud flats in the Gulf of Maine. Little is known about the life history of G. dibranchiataand management of the fishery is minimal. The goal of our study was to determine the population genetics of several Maine populations in order to inform management. We sequenced the neutral mitochondrial cytochrome c oxidase I (COI) marker in seven populations along the coast of Maine. A total of 486 nucleotides were sequenced in each individual, yielding 13 haplotypes, with 94% of them haploytpe 1. There was very little to no genetic differentiation among populations in the south (FST of less than 0.05), and there was only moderate differentiation between one of the most northern sites and the most southern site (FSTbetween 0.05 and 0.15). This lack of genetic differentiation indicates the populations are genetically linked via gamete dispersal. Consequently, the bloodworm fishery in the State of Maine can be managed at the scale of the Gulf of Maine(Graphical abstract).