Acoustic and Visual Survey of Humpback Whale (Megaptera novaeangliae) Distribution in the Eastern and Southeastern Caribbean Sea

—Humpback whales (Megaptera novaeangliae) historically ranged throughout the eastern and southeastern Caribbean Sea during the winter months. Commercial whaling from the 1820s to the early 1900s depleted the population. A combined passive acoustic and visual survey for humpback whales was conducted to assess the current winter distribution of this species in areas where it was exploited to depletion, and to evaluate the effectiveness of using passive acoustic survey methods to detect and locate humpback whales. Visual surveys were conducted independently but simultaneously with acoustic surveys to compare both detection methods. Humpback whale song was detected throughout the entire survey area, indicating that the species continues to occupy its historical range. A total of 31 sightings were made (n = 46 individuals, including three calves). In contrast, at least 78 unique acoustic detections of different singing males was made. The greater number of whales detected acoustically demonstrated the advantage of passive acoustic methods over visual methods for detecting male singing humpback whales; however, some sightings were not detected acoustically, demonstrating that visual methods are superior for detecting non-vocalizing whales. The number of whales detected indicates that the abundance of humpbacks in the eastern and southeastern Caribbean Sea is considerably lower than it was during the 19 century whaling period, and much lower than present day abundance in the primary wintering areas in the northeastern Greater Antilles.