Salinity and temperature structure of a freezing Arctic fjord—monitored by white whales (Delphinapterus leucas)

In this study we report results from satellite‐linked conductivity‐temperature‐depth (CTD) loggers that were deployed on wild, free‐ranging white whales to study the oceanographic structure of an Arctic fjord, Storfjorden, Svalbard. The whales dove to the bottom of the fjord routinely during the study and occupied areas with up to 90% ice‐cover, where performance of conventional ship‐based CTD‐casts would have been difficult. During the initial period of freezing in the fjord, over a period of approximately 2 weeks, 540 CTD profiles were successfully transmitted. The data indicate that Storfjorden has a substantial inflow of warm North Atlantic Water; this is contrary to conventional wisdom that has suggested that it contains only cold Arctic water. This study confirms that marine‐mammal‐based CTDs have enormous potential for cost‐effective, future oceanographic studies; many different marine mammal species target oceanographic discontinuities for foraging and thus may be good ‘adaptive samplers’ that naturally seek areas of high oceanographic interest.