The African penguin population in the Western Cape has plummeted from more than 30 000 breeding pairs in 2005 to just 12 000 in 2008 - the lowest level yet recorded.
On Dyer Island off Gansbaai, 90 percent of the penguins have disappeared in the past 30 years, and there are fears that the bird, which breeds only in South Africa and Namibia, may face extinction.
There has also been a huge decrease in penguin numbers in Namibia in the past 50 years.
Scientists say the drop in numbers is "alarming" and it appears a scarcity of food may be the cause.
Marine and Coastal Management (MCM) has set up a joint two-year programme with CapeNature to see whether closing fishing around the penguin breeding islands would boost their food source and help swell their numbers.
Fishing for sardines and pilchards, the penguins' main food source, has been banned since January in a 20km radius around Dassen Island off Yzerfontein on the West Coast.
Fishing is allowed around Dyer and Robben islands, the other two major breeding islands. Scientists are to compare the findings from the three islands.
One part of the project is to see how far penguins swim to fish, where they go, how many times they dive, to what depth, and the sea temperature.
Certain penguins are being fitted with tiny "backpacks" - global positioning system (GPS) transmitters - for about two days, then recaptured and the information downloaded.
Deon Geldenhuys, CapeNature conservation manager at Dyer Island, said: "We want to see how hard the penguins have to work to get their food.
It's too early to say anything for certain, but it looks as if the guys are working a lot on Dyer. They seem to be staying away longer and diving deeper."
The time penguins were away from their nests, their breeding success, and the trends in their breeding are also being recorded by MCM, says Rob Crawford.
Other than the GPS monitoring, several hundred penguins on Robben and Dassen islands have been fitted with microchips, similar to those for pets.
Transponder readers, set up at the island colonies, record each time the birds pass by. Penguin parents take turns going to sea to fish, with one staying at the nest.
Article courtesy of IOL@