The First Satellite Flipper Tag Deployments on Steller Sea Lions Allow Tracking Beyond the Annual Molt

Abstract

Entanglement in marine debris and fishing gear is increasingly recognized as a serious source of human-caused mortality for pinniped population world-wide and has been shown to contribute to Steller sea lion injury and mortality. As such, our primary goal in testing these location-only satellite flipper tags was to track post-entanglement response survival of Steller sea lions in Southeast Alaska, USA. The minimum data set necessary to determine post-release survival included: (a) location data sufficient to demonstrate movement indicating the tag was still attached to a live sea lion, and (b) tag endurance sufficient to track a disentangled sea lion beyond the molt (most entanglement response occurs during the summer in conjunction with other Steller sea lion research so tags glued to the pelage typically only last two to three months before falling off). For this study, we tested Wildlife Computers (Redmond, Washington, USA) Smart Position and Temperature (SPOT) 6 Model 371B inline satellite tags (SPOT 6 tags) on Steller sea lions. This first application of attaching SPOT 6 satellite flipper tags on otariids was a success with tags transmitting up to 2.05 years. Overall, the benefits of these tags outweighed their limitations and for the first time, allowed us to track Steller sea lions beyond the annual molt.