A study published this week in Ostrich: Journal of African Ornithology reveals that more than 60,000 African penguins perished from starvation between 2004 and 2012 — largely as a result of a dramatic collapse in sardine stocks off South Africa’s west coast.
The research, conducted by scientists from the University of Exeter and the South African Department of Forestry, Fisheries and the Environment, focused on two of the species’ most critical breeding colonies: Dassen Island and Robben Island, both located near Cape Town. On these islands, over 95 percent of the penguins that bred in 2004 had died within eight years.
The siren-call for alarm lies in the biology of the penguins themselves. Each year they undergo a moulting period — a roughly three-week phase during which they shed and regrow their feathers. During this time, the birds remain on land and cannot forage. To survive, they must first build up ample fat reserves by eating heavily. But over the period studied, sardine biomass — the primary prey for these penguins — fell to below a quarter of its historic maximum almost every year off the west coast of South Africa.
According to study co-author Richard Sherley, low food availability meant many penguins did not accumulate sufficient fat before moulting or could not recover quickly enough afterward, causing mass starvation. “If food is too hard to find before they moult or immediately afterwards, they will have insufficient reserves to survive the fast,” he explained.
Scientists point to a combination of climate-driven changes — especially shifts in water temperature and salinity that disrupted sardine spawning — and overfishing as the root causes of the collapse in sardine populations. While sardines began spawning more successfully off the south coast, commercial fishing efforts remained concentrated to the west of Cape Agulhas, intensifying pressure on the already diminished sardine stocks.
The fate of the African penguin underscores a decades-long decline. Over the past three decades, the global population of the species has shrunk by nearly 80 percent. As of last year, the penguin has been classified as critically endangered, with fewer than 10,000 breeding pairs remaining worldwide.
In response to the crisis, authorities have put in place protective measures, including a ban on commercial purse-seine fishing near six of the largest penguin-breeding colonies — including Dassen and Robben Islands — in hopes of giving the species a fighting chance. Conservation efforts also include building artificial nests, managing predators, and hand-rearing adults and chicks in dire need.
But the scientists warn that these measures may not be enough. A marine biology expert not part of the study described the results as “extremely concerning,” pointing out that low fish stocks pose a risk not only to the penguins but to other marine species that depend on small pelagic fish.
The collapse of the African penguin population raises broader ecological alarm bells: when a key prey species like sardines vanishes or drastically dwindles, the effects ripple across the entire food web. Without swift, coordinated action — including sustainable fisheries management, monitoring of oceanographic conditions, and long-term conservation planning — these iconic seabirds may disappear from the wild within years.
