Managing big boys: a case study on remote anaesthesia and satellite tracking of adult male New Zealand sea lions (Phocarctos hookeri)

Context. Handling animals is essential for many applications in wildlife management. However, currently there are limited techniques to safely handle and move large mobile pinnipeds, particularly when they cannot be physically restrained first. Such animals can be the cause of many land-based wildlife-human conflicts. The New Zealand ( NZ) sea lion (Phocarctos hookeri) is the world's rarest and second largest otariid, and is in severe decline. Although most NZ sea lions live on uninhabited NZ subantarctic islands, a small population is recolonising the coastline of Otago, NZ and this close proximity with humans can cause conflict. Aims. The aim of this research was to assess a method of remote chemical anaesthesia for its ability to safely and practically immobilise large pinnipeds to allow attachment of satellite tracking equipment and to handle and potentially move animals if in situations of conflict. Methods. The chemical anaesthetic Zoletil (R) was remotely applied to immobilise adult male NZ sea lions at Enderby Island, Auckland Islands, to allow handling and the application of satellite tracking equipment. Key results. Six adult males weighing up to 330 kg were successfully anaesthetised, weighed and measured. Two of these had satellite location tags attached, which showed two very different post-breeding movement patterns by adult males and indicated minimum overlap with local. sheries activities. Conclusions. This remote anaesthesia technique was successful for adult male NZ sea lions and could be used for the immobilisation and management of other large mobile pinnipeds. Implications. The ability to anaesthetise and safely handle large adult male pinnipeds will provide better management in areas where animals come in close contact with human populations with possible lethal interactions or where attachment of monitoring equipment is required to investigate population parameters or possible lethal interactions.