The Southern African Foundation for the Conservation of Coastal Birds (Sanccob) is frantically rescuing oil-covered sea birds near Port Elizabeth.
The birds were affected when a refuelling of the MV Chrysanthi S ship went wrong and up to 400 litres of oil spilt in the Port of Ngqura, about 20km from Port Elizabeth.
"SANParks (SA National Parks) has brought us 21 African penguins, one Cape gannet and one Cape cormorant so far. They are all endangered species," Sanccob's Christian Triay told News24 on Wednesday.
He added that seven more African penguins were in transit as the fallout of the spill was calculated.
"We expect to receive anywhere between 20 and 30 more."
Most of the birds affected are from Bird, St Croix, Brenton and Jaheel islands.
"The area is particularly sensitive and there could be many more birds that could be impacted," said Triay.
Sanccob said that in a 2016 spill of 100 litres of oil, it treated 92 adults and 32 chicks and the spill which happened on Saturday could have a more dramatic effect.
"Those islands are extremely sensitive environments and there are 2 000 breeding pairs on Bird Island," said Triay.
The South African Maritime Safety Authority said that it detained the ship while investigations were under way.
"We're still investigating and the vessel has been detained to allow us to conclude all the interviews with all the people who were involved and present, particularly the captain," Samsa spokesperson Tebogo Ramatjie told News24.
Ramatjie said that incidents of oil spillage had declined in recent times because ship captains are aware of the technology that Samsa employs to monitor marine traffic.
"This is a very isolated incident, and without pre-empting what the result of the investigation would be, it looks like an accident.
"Over the years, we've seen that ships that pass our shores are behaving themselves. We employ very sophisticated technology."
There are long-term effects for oiled sea birds.
"The reproductive success of African penguins will decline and you'll have pairs of penguins which will stick together but won't produce young," said Triay.
Sanccob discouraged people from conducting their own sea bird rescue missions. The organisation has specific methods to do rescues.
"The sea birds, when you pick them up, remember they are wild animals and they will bite. In the last few years, we've trained all our staff in the incident command system," said Triay.
"We've developed protocols over the years and all our staff follow those protocols."
Sanccob also employs a team of volunteers to help with sea bird rescues and Triay encouraged the public to report birds in trouble.
"The best thing to do is people should contact Sanccob because you do need a permit to handle and transport sea birds."