Extensive use of the high seas by Vulnerable Fiordland Penguins across non-breeding stages

Migratory seabirds experience varying levels of both protection and threats as they travel across marine regions and countries’ jurisdictions. Studying their seasonal distribution provides insights into the full range of exploited habitats and potential gaps in conservation policy existing in the visited areas. Here we used light-based geolocation to examine the seasonal at-sea distribution of an endemic seabird from New Zealand, the Fiordland Penguin Eudyptes pachyrhynchus, with respect to Economic Exclusive Zones (EEZs). We show that the five birds successfully tracked from the remote Open Bay Islands exploited vast areas in the South Pacific Ocean and used contrasted habitats across seasons. During extensive periods at-sea before and after moulting, Fiordland Penguins reached cold oceanic waters across the Subantarctic Front (Subantarctic and Polar Frontal zones, 2–10 °C), ranging 1500–2000 km in the southwest of their colony. Across both these trips, all birds distributed extensively outside New Zealand’s EEZ (nearly 50% of time), into areas beyond national jurisdiction providing little tangible protection, and some temporarily entered Australia’s EEZ. This contrasted with previous results from the breeding season, when the Penguins distributed exclusively within New Zealand’s EEZ, in relatively shallow and warm (c. 12–20 °C) waters north of the Southern Subtropical Front. Annually, the tracked Penguins spent 102 days outside New Zealand waters, of which 79 days in the high seas. Our results provide new perspectives on pertinent conservation strategies for migratory “endemic” Penguins. Year-round approach on the at-sea ecology of species seems fundamental for adequate management of threatened marine biodiversity.