An oil spill has occurred in Algoa Bay, with around 80 litres of fuel entering the sea.

The South African Maritime Safety Authority (Samsa) and other stakeholders have started clean-up efforts and an investigation is under way.

"Samsa has initiated all relevant oil spill response teams as per the National Oil Spill Contingency Plan to assist with the containment and clean-up operation following an oil spill in Algoa Bay on [Wednesday]," Samsa spokesperson Tebogo Ramatjie said.

The spill occurred on Wednesday at around 13:00 when a Croatian-flagged vessel, MV Solin, took bunkers offshore from the bunker tanker Sea Express at the Algoa Bay anchorage number 1.

"It is estimated that at least 80 litres of heavy fuel oil entered the seawater after a fuel tank on board the receiving vessel overflowed. Oil spill booms were deployed, and some clean-up operations have commenced," said Ramatjie.

The oil spill could have a devastating effect on bird species at the nearby St Croix Island, according to Southern African Foundation for the Conservation of Coastal Birds (Sanccob) spokesperson Ronnis Daniels.

"We are concerned about the trajectory of the remaining oil that could hit the shoreline and affect seabirds on St Croix Island. We are always prepared for such crises and are currently in response mode to mobilise staff and equipment to rescue, stabilise and wash birds that might need rehabilitation if oiled," Daniels said.

Oiled seabirds can be reported to Sanccob Gqeberha on 041 583 1830 and after-hours emergencies on 064 019 8936, Daniels said.

Many migratory bird species will be at risk if the oil reaches the shore, but Sanccob staff are especially worried about the local penguin population. African penguin numbers at St Croix have declined by more than 70% since 2014, making this previously world's largest breeding colony rank only fourth largest in South Africa in 2021.

"The African penguin population census carried out in 2021 by members of the Department of Forestry, Fisheries and the Environment revealed there are only around 1 500 African penguin breeding pairs, compared to 3 638 breeding pairs from the previous census in 2019 – an alarming decline for this endangered species. With the remaining birds already threatened by the lack of food, we are extremely concerned about the added threats brought about by shipping practices in the surrounds," said Daniels.

Samsa has detained the vessel and is busy investigating the incident, according to Ramatjie.