Long-term individual sighting history database: An effective tool to monitor satellite tag effects on cetaceans

Abstract

During the last 3 decades, tagging technology has been used to study different aspects of cetacean ecology. Tags implanted in animal's blubber, muscle and surrounding tissue have produced successful results, providing information on long-term movements. However, apart from the reports of 'divots' (depressions) and swelling at the tag sites in re-sighted large whales, little has been published about the long-term effects of tagging. Based on sighting history databases of photo-identified blue whales, we monitored the wound site of a satellite tag on an adult female blue whale over a period of 16 yr (1995 to 2011). This report describes the swelling reaction to a broken subdermal attachment from a tag designed early in the evolution of large whale tagging. The tag attachment remained embedded for a decade (much longer than expected), and may have affected the female's reproductive success during this period. The whale's calving history showed a total of 3 calves; 2 were prior to, and one ocurred after, the swelling period (1999 to 2007). We demonstrate the value of long-term monitoring programs in evaluating tag impacts, especially on endangered species.