Initial impact of the Treasure oil spill on seabirds off western South Africa

On 23 June 2000, the bulk ore carrier MV Treasure sank off western South Af rica between Dassen and Robben islands, which individually currently suppor t the largest and 3(rd) largest colonies of African penguins Spheniscus dem ersus. Subsequently, more than 19 000 penguins were oiled, almost twice the previous highest number of seabirds oiled during a single event in souther n Africa (10 000 penguins after the sinking of the Apollo Sea in June 1994) . About 19 000 oiled penguins were collected for cleaning and care and abou t 150 oiled adults died in the wild. Some 19 500 unoiled penguins were caug ht at Dassen and Robben islands and relocated to Port Elizabeth, 800 km to the east, to remove them from waters affected by the oil. Of all penguins c aught, which amounted to 20% of the total species population. less than 2 0 00 died within the first month, considerably less than in the Apollo Sea sp ill. This can be attributed to improved transport of penguins and the rapid arrival at rescue centres of experts able to administer emergency care. Ho wever, resources were severely extended and mortality would probably have b een considerably higher had Large numbers of birds not been removed from th e area affected by the oil. Many relocated birds returned to their home isl ands within a month of being released, but considerable disruption of pair bonds is expected to result from mortality, different periods in captivity and disruption of moult cycles. This is likely to result in decreased breed ing success. Recruitment to colonies will also be reduced by substantial lo ss of chicks and eggs. Although more than 3 000 orphaned chicks were collec ted for captive rearing, an estimated 4 000 died at the islands before they could be rescued. Up to 20% of bank cormorants Phalacrocorax neglectus at Robben Island, the 3(rd) largest colony of the species in South Africa, die d. There was low success in catching oiled cormorants and in saving those t hat were caught. Of 53 grown birds of four species of cormorant that were o iled and caught, only 17 survived. Captive rearing of bank cormorant chicks , which it was feared may have: been orphaned. proved more successful. Spil t oil had minor impact on gulls. rems and shorebirds in the region.