Mass sardine die-off: new threat to African Penguins?

Seabird and marine scientists are closely monitoring the potential impact of a mass sardine die-off off the Cape coastline on the already critically endangered African Penguin population. Preliminary evidence shows weight loss in penguins at three of the seven breeding colonies, Dyer Island, Stony Point and Robben Island, coinciding with the sardine die-offs.

However, some signs of recovery are also observed. The sardine die-off could be caused by a viral infection, the pilchard herpesvirus, though this has yet to be confirmed through laboratory studies. This is the first time the virus has been reported in South African sardines. The African Penguin is listed as "critically endangered" and the species is being closely monitored.

Current estimates put the population at around 19,800 mature individuals and 8,750 to 9,900 breeding pairs. Researchers are using weighbridges at five of the seven breeding colonies to track the penguins' health. Preliminary data from Dyer Island suggest a significant decline in average weight of birds passing over the weighbridge for about ten to twelve days, though it appears to have recovered somewhat.

Similar declines have been observed at Stony Point and a dip in weight at Robben Island, but these have since recovered. Researchers are concerned because mass sardine die-offs in Australian waters in the 1990s associated with the same virus coincided with large mortalities in the Little Penguin population and significantly reduced its breeding success.

The African Penguin is being intensively monitored at its breeding sites. The Department has started laboratory investigations and convened an urgent briefing with industry representatives to formulate a coordinated response plan for sardine mortality associated with the virus in South African waters.