Insights into the Underwater Diving, Feeding, and Calling Behavior of Blue Whales from a Suction-Cup- Attached Video-Imaging Tag (CRITTERCAM)

New techniques and studies have provided a better understanding of some aspects of blue whale biology. This has included: 1) photographic identification studies that have provided estimates of abundance and movements (Sears et al., 1987; Calambokidis et al., 1990; Sears and Larsen, 2002; Calambokidis and Barlow, 2004), 2) ship surveys to examine distribution and abundance (Barlow, 1994; Forney and Barlow, 1998; Gerrodette and Forcada, 2003; Calambokidis and Barlow, 2004), 3) satellite tagging to examine movements (Mate et al., 1999), 4) acoustic studies using detections of vocalizations to examine the distribution, seasonality, and singing behavior of blue whales (Stafford et al., 1998, 1999; McDonald et al., 2001; Burtenshaw et al., 2004; Oleson et al. 2007c). The underwater behavior of all whale species is extremely difficult to study. Suction-cupattached archival tags have begun to provide more details about underwater behaviors, including feeding and social behaviors (Goldbogen et al., 2006; Oleson et al., 2007a; Johnson and Tyack, 2003; Baird et al., 2005, 2006). Blue whales, like other rorquals, are known to lunge feed, which is to use their expandable throats to engulf large volumes of prey and water before filtering this mixture through their baleens (Goldbogen et al., 2007). Dive data from blue and fin whales have revealed a series of rapid vertical movements underwater presumed to be feeding lunges (Croll et al., 1998, 2001a, 2001b; Acevedo et al., 2002; Goldbogen et al., 2006, 2007; Schorr et al., 2005; Calambokidis et al., 2003, Dolphin, 1987). Here we examine some of the specific insights into feeding and calling behavior of blue whales provided by the images revealed from the deployment of CRITTERCAMs on blue whales. B Introduction lue whales are the largest animals that have ever lived. Their large size made them prime targets during the modern era of commercial whaling when fast catcher boats and explosive harpoons allowed whalers to hunt them. Consequently their populations were depleted from around 300,000 to around 10,000 animals (Gambell, 1979). Despite their protection from whaling in 1966 by the International Whaling Commission, their numbers remain very low and the lack of a significant recovery has prompted concern. While recent revelations of the continued illegal hunting of blue whales past 1966 have provided one explanation about their slow recovery (Mikhalev, 1997), other factors such as the availability of adequate prey as a result of changes in krill abundance driven by climate change or competition with other species cannot be ruled out.