The Ministry of Water and Environmental Affairs says the South African Navy does not have any mid-frequency sonar of the type that can affect cetaceans.

The ministry was responding to questions asked by Congress of the People MP NJ JvR Koornhof regarding the death of approximately 45 false killer whales at Kommetjie, south of Cape Town, in May.

Some local media reports blamed naval sonar for the beaching of the oceanic dolphins.

The ministry added departmental officials and scientists at the University of Pretoria were still drafting a report on the beaching. "Various samples were collected from each whale [sic] and once analysed, the report can be completed. Preliminary results indicate that the animals were healthy with no obvious cause for the stranding."

The wikipedia notes that active, mid-frequency, sonar may harm marine animals, "although the precise mechanisms for this are not well understood."