Abundance and distribution of avian and marine mammal predators of sardine observed during the 2005 KwaZulu-Natal sardine run survey

  • SH O’Donoghue
  • PA Whittington
  • BM Dyer
  • VM Peddemors

Abstract

Opportunistic observations to determine the relative abundance and distribution of marine mammal and seabird predators of sardine   Sardinops sagax were carried out during a dedicated multidisciplinary research survey off the South African east coast in June and July of 2005 that was timed to coincide with the annual sardine run. Associations between different predator species, between predators and clupeoids, and between predators and oceanographic variables, were examined. Species’ distributions were primarily separated by  latitude and distance from shore. Bryde’s whale Balaenoptera edeni, African penguin Spheniscus demersus, Cape cormorant Phalacrocorax capensis and West Coast round herring Etrumeus whiteheadi were  predominantly found in the cool southern part of the survey region. Peak sardine run activity occurred within 4 km of shore at the northward limit of a strip of cool water (<21 °C) stretching along the  East Coast. The principal predators associated with this activity were common dolphins Delphinus capensis and Cape gannets Morus capensis, and their nearshore distribution was associated with sardine and East Coast round herring E. teres. Few clupeoids were encountered along the KwaZulu-Natal continental shelf, although patches of high sardine abundance were recorded near the shore immediately south of Durban. It is clear that during the 2005 survey the sardine run terminated in  this region, probably as a result of the nearshore intrusion of warm water from the Agulhas Current.

Keywords: Cape gannet, chlorophyll a, common dolphin, hydrographic survey, Sardinops sagax, sardine run, SST

African Journal of Marine Science 2010, 32(2): 361–374

Author Biographies

SH O’Donoghue
School of Biological and Conservation Sciences, University of KwaZulu-Natal, Private Bag X54001, Durban 4000, South Africa
PA Whittington
Department of Zoology, PO Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031, South Africa
BM Dyer
Oceans and Coasts, Department of Environmental Affairs, Private Bag X2, Rogge Bay 8012, South Africa
VM Peddemors
School of Biological and Conservation Sciences, University of KwaZulu-Natal, Private Bag X54001, Durban 4000, South Africa
Section
Articles

Journal Identifiers


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