Confirmation of the occurrence of a second killer whale morphotype in South African waters

  • PB Best
  • MA Meÿer
  • M Thornton
  • PGH Kotze
  • SM Seakamela
  • GJG Hofmeyr
  • S Wintner
  • CD Weland
  • D Steinke

Abstract

Killer whales Orcinus orca occur worldwide in a number of morphotypes that differ in size, pigmentation, acoustic behaviour, food type and genetics – some may indeed warrant subspecific or even specific status. Until recently, all killer whales in South African waters were referred to a single morphotype, Type A, but three individuals (two males and one female) that have stranded since 1969 differ in several respects from other killer whales examined from the region. Adult length is some 1–1.5 m smaller, appendages such as dorsal fin and flippers tend to be relatively larger, and tooth wear is excessive. Although dietary information is scant, one stomach contained the remains of several elasmobranchs, identified from a DNA subsample as blue sharks Prionace glauca, a dietary item that, if habitual, might account for the tooth wear. This morphotype, referred to here as ‘flat-toothed’ and which in several respects resembles the offshore form in the North Pacific and the Type 1 form in the North Atlantic, does not seem to have been recorded previously from the Southern Hemisphere.

Keywords: blue shark, dentition, morphometrics, Orcinus orca, prey

African Journal of Marine Science 2014, 36(2): 215–224

Author Biographies

PB Best
Mammal Research Institute, Whale Unit, University of Pretoria, c/o Iziko South African Museum, Cape Town, South Africa
MA Meÿer
Branch: Oceans and Coasts, Department of Environmental Affairs, Cape Town, South Africa
M Thornton
Mammal Research Institute, Whale Unit, University of Pretoria, c/o Iziko South African Museum, Cape Town, South Africa
PGH Kotze
Branch: Oceans and Coasts, Department of Environmental Affairs, Cape Town, South Africa
SM Seakamela
Branch: Oceans and Coasts, Department of Environmental Affairs, Cape Town, South Africa
GJG Hofmeyr
Port Elizabeth Museum at Bayworld, Port Elizabeth, and Department of Zoology, Nelson Mandela Metropolitan University, Port Elizabeth, South Africa
S Wintner
KwaZulu-Natal Sharks Board, Umhlanga Rocks, and Biomedical Resource Unit, University of KwaZulu-Natal, Durban, South Africa
CD Weland
Canadian Centre for DNA Barcoding, Biodiversity Institute of Ontario, University of Guelph, Guelph, Ontario, Canada
D Steinke
Canadian Centre for DNA Barcoding, Biodiversity Institute of Ontario, University of Guelph, Guelph, Ontario, Canada
Published
2014-07-30
Section
Articles

Journal Identifiers


eISSN: 1814-2338
print ISSN: 1814-232X