laid eggs were sold. This added to the drastic decline of the African penguin population around the Cape coast, a decline which was hastened by the removal of guano from islands for use as fertiliser, eliminating the burrowing material used by penguins. Oil spills Penguins remain susceptible to pollution of their habitat by petrochemicals from spills, shipwrecks and cleaning of tankers while at sea. Accounts of Africa penguins impacted by oil date back to the 1930s. African penguins' exposure to oil spills is both chronic (higher frequency small discharges of oil at sea) and acute (rare maritime disasters where large volumes of oil are released in a single event). Penguins of many species have been impacted by oil spills across the southern hemisphere. In 1948, the tanker Esso Wheeling sank, subsequently oiling and killing thousands of penguins of the Dyer Island colony. In 1953, dead penguins were among a range of dead birds, fish and other marine life that washed ashore after the tanker Sliedrecht was holed and spilled oil near Table Bay. In 1971, the SS Wafra oil spill impacted the African penguin colony of Dyer Island. In 1972, oil spilt following the Oswego-Guardian and Texanita collision oiled roughly 500 penguins. In 1975, newspapers reported that oil pollution from shipwrecks and the pumping of bilges at sea had killed tens of thousands of African penguins. At the time, the Dassen Island colony was being passed by 650 oil tankers each month because the Suez Canal had become blocked with wrecked vessels, thus increasing maritime traffic past the Cape of Good Hope. In 1979, an oil spill prompted the collection and treatment of 150 African penguins from St. Croix Island near Port Elizabeth. The animals were later released at Robben Island and four of them promptly swam back to St. Croix Island, surprising scientists. In 1983, the exposure of penguins of Dassen Island to the oil slick from the Castillo de Bellver was also a topic of concern given the penguins' conservation status at the time, but owing to the prevailing wind and current, only gannets were oiled. 1994 MV Apollo Sea disaster African penguin casualties were significant following the sinking of the MV Apollo Sea and a subsequent oil slick in 1994. 10,000 penguins were collected and cleaned, of which less than half survived. 2000 MV Treasure crisis Disaster struck on 23 June 2000, when the iron ore tanker