Marine protected areas and migratory species: residency of green turtles at Palmyra Atoll, Central Pacific

Protected areas are a cornerstone of conservation strategies globally, yet questions remain about their impacts, including on highly migratory species. The Palmyra Atoll National Wildlife Refuge, one of the Northern Line Islands in the Central Pacific, contains a regionally significant green turtle Chelonia mydas foraging ground. Residency patterns of this species were investigated through satellite telemetry (n = 15 males, 1 female, 2 subadults) and flipper tagging (n = 555) between 2008 and 2013. Almost every captured turtle was flipper-tagged, but telemetry efforts focused primarily on adult males, which have been studied infrequently. Overall, the turtles tracked during 4076 transmission days (mean = 227, range = 37 to 633) had high site fidelity and small home ranges, and remained close to their capture sites in waters 50 m deep. Five turtles were tracked for >1 yr, but none left Palmyra on annual breeding migrations. Only one satellite-tracked turtle departed the atoll, covering a total distance of ~5600 km in a near-circular loop. Similarly, flipper tag recaptures on the atoll (n = 67) occurred near the original capture site. However, additional tags were recovered from 1 female in Kiritimati, Northern Line Islands, and from 1 subadult in Kosrae, Micronesia, ~690 and 3800 km away from Palmyra, respectively. Such extended, spatially restricted residency with low turnover is expected in small, high-quality habitats. The study highlights the importance of this protected area, which harbors regionally endangered turtles whose movements over several years are almost entirely encompassed within its established boundaries.