Humpback whale “super-groups” – A novel low-latitude feeding behaviour of Southern Hemisphere humpback whales (Megaptera novaeangliae) in the Benguela Upwelling System
Southern Hemisphere humpback whales (Megaptera novaeangliae) generally undertake annual migrations from polar summer feeding grounds to winter calving and nursery grounds in subtropical and tropical coastal waters. Evidence for such migrations arises from seasonality of historic whaling catches by latitude, Discovery and natural mark returns, and results of satellite tagging studies. Feeding is generally believed to be limited to the southern polar region, where Antarctic krill (Euphausia superba) has been identified as the primary prey item. Non-migrations and / or suspended migrations to the polar feeding grounds have previously been reported from a summer presence of whales in the Benguela System, where feeding on euphausiids (E. lucens), hyperiid amphipods (Themisto gaudichaudii), mantis shrimp (Pterygosquilla armata capensis) and clupeid fish has been described. Three recent research cruises (in October/November 2011, October/November 2014 and October/November 2015) identified large tightly-spaced groups (20 to 200 individuals) of feeding humpback whales aggregated over at least a one-month period across a 220 nautical mile region of the southern Benguela System. Feeding behaviour was identified by lunges, strong milling and repetitive and consecutive diving behaviours, associated bird and seal feeding, defecations and the pungent “fishy” smell of whale blows. Although no dedicated prey sampling could be carried out within the tightly spaced feeding aggregations, observations of E. lucens in the region of groups and the full stomach contents of mantis shrimp from both a co-occurring predatory fish species (Thyrsites atun) and one entangled humpback whale mortality suggest these may be the primary prey items of at least some of the feeding aggregations. Reasons for this recent novel behaviour pattern remain speculative, but may relate to increasing summer humpback whale abundance in the region. These novel, predictable, inter-annual, low latitude feeding events provide considerable potential for further investigation of Southern Hemisphere humpback feeding behaviours in these relatively accessible low-latitude waters.
Mammal Research Institute Whale Unit, University of Pretoria, Pretoria, Wynberg, South Africa / Current address: Research Chair: Oceans Economy, Cape Peninsula University of Technology, Cape Town, South Africa;Department of Environmental Affairs, Branch Oceans and Coasts, Victoria & Alfred Waterfront, Cape Town, South Africa;Department of Environmental Affairs, Branch Oceans and Coasts, Victoria & Alfred Waterfront, Cape Town, South Africa;Department of Environmental Affairs, Branch Oceans and Coasts, Victoria & Alfred Waterfront, Cape Town, South Africa;Mammal Research Institute Whale Unit, University of Pretoria, Pretoria, 0001, South Africa [c/o 16 Ebor Rd, Wynberg, South Africa] / Current address: Marine Stewardship Council, 1 Snow Hill, London, United Kingdom;Department of Biology, Hopkins Marine Station, Stanford University, 120 Ocean View Blvd, Pacific Grove, CA, United States of America;12 Victory Way, Simon’s Town. Cape Town, South Africa;The Marine Mammal Laboratory, Alaska Fisheries Science Center, 7600 Sand Point Way NE. Seattle, WA, United States of America;Department of Environmental Affairs, Branch Oceans and Coasts, Victoria & Alfred Waterfront, Cape Town, South Africa;Department of Environmental Affairs, Branch Oceans and Coasts, Victoria & Alfred Waterfront, Cape Town, South Africa;Mammal Research Institute Whale Unit, University of Pretoria, Pretoria, Wynberg, South Africa;ConserBio Foundation, Heredia, Costa Rica;Department of Agriculture, Forestry and Fisheries, Branch: Fisheries Management, Foretrust Building, Foreshore, Rogge Bay, Cape Town, South Africa
Recommended Citation:
Ken P. Findlay,S. Mduduzi Seakamela,Michael A. Meÿer,et al. Humpback whale “super-groups” – A novel low-latitude feeding behaviour of Southern Hemisphere humpback whales (Megaptera novaeangliae) in the Benguela Upwelling System[J]. PLOS ONE,2017-01-01,12(3)