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The marine ecosystem off the West Coast has taken a severe knock with the disappearance of the sardine stocks - the major food source for thousands of seabirds - and the African penguin population has dropped to the lowest level ever recorded.
In Namibia, where sardine stocks appear to have collapsed, the situation is critical, and ornithologists say the seabird populations are "going down the tubes". The Namibian gannet population has dropped to 90 percent of what it was 50 years ago, and the Namibian pilchard fishing industry has packed up for the season, unable to afford the cost of staying at sea without landing catches. Seals are reported to be starving on the Namibian coast.
On South Africa's West Coast, seabirds appear to be surviving on bits of hake discarded at sea by fishing vessels. On Dassen Island, a nature reserve and major seabird breeding colony near Yzerfontein, only half the number of penguins have bred this year compared to last year, while at Bird Island off Lamberts Bay, where there are normally 2 000 pairs of breeding Cape cormorants, there is just one pair breeding on the island.
In the Western Cape overall, 20 000 African penguins have disappeared from the breeding colonies since 2004, and 10 000 have disappeared in Algoa Bay in the Eastern Cape in the last three years.
It appears that the sardine stocks have moved south which has had a knock-on effect not only on the ecosystem, but on the economy of the West Coast.
Tony Williams, ornithologist for CapeNature, said on Monday that there were only six islands in the world where gannets bred: Mercury, Ichabo and Possession Islands in Namibia, Malgas and Bird Island on the West Coast and Bird Island in Algoa Bay.
"In Namibia, the seabird populations are going down the tubes. The sardines appear to have been almost wiped out and the whole system appears to have changed. The jelly fish have increased and they eat the fish eggs and larvae, which means fewer fish, and if there are no fish, the seabirds don't breed. I'm not sure if it's possible ever to reverse what's happened in Namibia. It looks as if, in the long-term, we're going to lose the whole lot, the birds and the fish - at least as an economically viable industry," Williams said.
Rob Crawford, ornithologist at Marine and Coastal Management, said the Namibian gannet and African penguin population had declined by 90 percent in the last 50 years.
"That puts a lot of pressure on us in South Africa, as the only other place in the world where these birds breed, to conserve our populations. But things are not looking good for these birds on the West Coast either. The amount of fish is hugely reduced on the West Coast, and stocks have moved south. We've lost 20 000 penguins in the Western Cape since 2004. They're not here breeding, they've not been recorded moulting, which they come ashore to do every year, which seems to suggest that they've gone.
"The signs are not good. We've lost another 10 000 penguins in Algoa Bay in the Eastern Cape since 2002, which together with the 20 000 in the Western Cape, puts the African penguin population at its lowest level ever recorded since scientists began keeping counts in 1956," Crawford said.
He said sardines formed up to 80 percent of gannets' diet. Analysis over the last few years revealed that sardines now accounted for less than 25 percent of their diet. Much of what they now ate consisted of discarded hake from fishing vessels.
Gannets and penguins were faithful to their breeding sites and would not move to follow the sardines eastwards, although some "pre-breeders" might do so.
"My hunch is that this is environmental change from a combination of factors. We're seeing fish moving south, rock lobster moving east, and more low oxygen events on the West Coast. The impact on seabirds is huge," Crawford said.
Carl van der Lingen, pelagic fish specialist at MCM, confirmed on Monday that sardine stocks had moved south from the West Coast. He said there had not been overfishing of sardines on the West Coast.