Hypothesis: Marine threespine stickleback manifest homing ability and site fidelity during their spawning period. Organism: The threespine stickleback, Gasterosteus aculeatus. Time and places: June 2015 and June 2016 (during the stickleback spawning period), Koliushkovaya Lagoon, Kandalaksha Bay, the White Sea. Methods: Stickleback were tagged on their inshore spawning grounds about 2 weeks after their inshore migration. We attached plastic tags to their dorsal spines, displaced them 100–300 m away from shore, and recaptured them inshore after periods of one hour to four days. Results: Stickleback caught on their spawning grounds in the lagoon, tagged and displaced a few hundred metres, were able to return to their home site within a day. Males and females exhibited no differences in homing ability. Most fish left their home site within four days of returning, however, indicating that site fidelity is weak. Stickleback caught outside the lagoon in the sea, and tagged and released in the lagoon, spread along the shore in accordance with the density of local fish.