Cetacean sightings near South Georgia islands, South Atlantic Ocean

Have whales returned to a historical hotspot of industrial whaling? The pattern of southern right whale Eubalaena australis recovery at South Georgia

“…The shore-based whaling stations closed in the 1960s and a moratorium on whaling from factory ships for all species other than minke whales was agreed by the International Whaling Commission (IWC) in 1979. Since then, 2 dedicated investigations into summer cetacean abundance in South Georgia waters have been carried out: a line transect survey in 1997 out to the 2000 m isobath along the north coast (Moore et al 1999) and a research cruise by Brazilian investigators in 2006(Rossi-Santos et al 2007. Cetacean observations were also made on other South Georgia expeditions, for exam-ple during dedicated krill surveys (Reid et al 2000, Hedley et al 2001, Reilly et al 2004, Širović et al 2006, Tarling et al 2012 and as part of a cetacean and seabird survey along the north Scotia Ridge (Joiris et al 2015).…”

Feeding grounds of the western South Atlantic humpback whale population

“…Although no estimates of humpback whale density at the SSI are available, the relative ease with which 25 humpbacks were photographed, together with the tracking results of Zerbini et al (2006), indicates that substantial numbers, and plausibly thousands of whales forming the majority of the population breeding off Brazil, may feed here at some stage during summer in the early 21st century. With coastal waters of South Georgia supporting very few humpbacks in recent years (Moore et al 1999, Rossi‐Santos et al 2007), in contrast to a century ago at the start of commercial whaling when the species was abundant (Tønnessen and Johnsen 1982), the focus of the summer distribution of this population appears to have changed, and may have shifted some 750 km to the southeast.…”

“…1) therefore appear to form at least part of the summer range of this population. However, doubt remains about whether this area is the main feeding ground, partly because relatively few humpbacks have been encountered in the region in recent decades (Moore et al 1999, Rossi‐Santos et al 2007). Despite an almost complete cessation of humpback whaling here by 1950 (only ca.…”

A Southern Ocean archipelago enhances feeding opportunities for a krill predator

“…The sighting rate at the Balleny Islands is also higher than previously seen around other island groups. At the South Shetland Islands, the sighting rate of humpback whales over a 5year survey was 0.39 sightings hr −1 (Santora et al, 2010) and at South Georgia, only one humpback whale group was seen over 110 hr of effort (Rossi-Santos, Baracho, Cipolotti, & Marcovaldi, 2007). While the overall continued increase in southern ocean humpback whales suggests that at least some of this disparity may reflect a temporal change, the high number of whale sightings and high krill abundance at the Balleny Islands suggests this area is important feeding habitat for humpback whales.…”