Recent surveys of the sea otter (Enhydra lutris) population on Kuril Islands

Abstract

Context Sea otters, an endangered species, require regular assessments of their distribution and abundance. These animals inhabit the coastal waters of the North Pacific, traversing from Japan through the Kurils, southern Kamchatka, Commander and Aleutian Islands, and the coasts of North America, to California. Although populations in America and the Commander Islands have been consistently monitored over recent decades, the same cannot be said for the Kuril Islands. Aim This study aims to estimate the state of sea otter populations on the Kuril Islands. Methods The study area encompassed a section of the Kuril archipelago, including Iturup, Urup, Broughton, Chirpoy, and Simushir Islands, surveyed from 2019 to 2023. Sea otters were counted along sections of the coastline, and published sources on other Kuril Islands were analysed. Key results There are several hundred sea otters within surveyed area, whereas in 1960–1980 ~2000 were reported. The total number of sea otters on the archipelago hardly exceeds 3000. The initial or normal number is not known, but the information on hunting indicates that it was much bigger. Up to the end of 19th century, at least ‘one thousand individuals’ had been harvested annually over several decades; this means that the total number was at least several tens of thousands. Conclusions Sea otter populations on the Kuril Islands are in decline, with poaching in the recent past identified as significant contributing factor in a part of the archipelago. Implications Urgent conservation measures are imperative to address the decline of sea otter populations.