Interactions between leatherback turtles and killer whales in Namibian waters, including possible predation

Abstract

Killer whales and leatherback turtles are infrequently sighted in the coastal waters of southern Africa. Year round observations in Walvis Bay, Namibia of killer whales (2003–2010) by multiple marine tour operators and opportunistic seasonal observations of leatherback turtles made during a cetacean research project in the area (2008–2010) have been collated. Visits to coastal waters by killer whales (n = 16) are sporadic and unpredictable but are slightly higher (n = 11) between late winter (August) and late summer (March). Leatherback turtles were only seen in the warmer periods of summer months (February–March) when the surface waters exceeded 15°C. Two interactions (one harassment and one probably predation) between killer whales and leatherback turtles have been recorded in Walvis Bay. This is the first report of killer whales eating leatherback turtles in the South Atlantic. These observations are noteworthy due to the low frequency of encounters of both species in the area, suggesting predation of turtles may be relatively common. Knowledge of the diet of killer whales is valuable due to the importance of dietary specialization in definition of ecotypes of the species.