The decline of South Africa’s African penguin population has not been gradual. It has been abrupt and devastating. New research shows that after 2004, sardine stocks west of Cape Agulhas collapsed to less than a quarter of their historical peak, triggering a sharp fall in adult penguin survival at key breeding colonies near Cape Town. At Dassen Island and Robben Island, researchers estimate that around 62,000 breeding adults died between 2004 and 2011. This loss represents roughly 95 percent of the penguins breeding at those sites in 2004. The study was led by scientists from the University of Cape Town and draws on two decades of colony monitoring.

African penguins face one non-negotiable annual test: molt. Once a year, adults come ashore for around three weeks, shed all their feathers at once, and fast completely on land. Survival depends on arriving with large fat reserves and then rapidly rebuilding body condition once molt ends. As sardines disappeared, more breeding adults failed to return for molt counts. These “missing moulters” are a critical signal. When penguins do not appear for molt, it usually means they died at sea, unable to accumulate enough energy before this high-risk period. The study shows a clear link between forage fish availability and adult survival. When sardine biomass fell below about 25 percent of historical levels, annual adult survival at both colonies dropped from roughly 0.78–0.84 to around 0.59. Over multiple years, that difference translated into tens of thousands of excess deaths. Environmental variability played a role, but fishing pressure compounded the crisis. West of Cape Agulhas, sardine exploitation exceeded 20 percent in several years between 2005 and 2010, peaking close to 80 percent in 2006. This placed intense pressure on the same prey penguins rely on to build fat reserves before molt. The timing matters. The overlap between heavy fishing pressure and the collapse in penguin survival strongly points to food scarcity as the dominant driver of adult mortality during this period. By 2024, African penguins were officially reclassified as critically endangered, reflecting how quickly prey loss and fishing pressure have pushed the species toward extinction in South Africa and Namibia.

Read more: Morrisons Extends Net Zero Strategy to Cover Its Entire Supply Chain

Penguin populations can sometimes absorb poor breeding years. They cannot absorb sustained losses of adults. Long-lived seabirds recover slowly once adult survival drops, even if breeding conditions improve later. The research shows that focusing only on chick numbers or breeding pairs can mask deeper problems. Adult survival, especially through the pre- and post-molt window, determines whether a colony persists or collapses. Some penguins attempted to shift their molt to colonies farther southeast, suggesting limited flexibility. But when prey scarcity spans an entire region, relocation offers little protection.

Explore OneStop ESG Marketplace: Sustainability

South Africa has introduced no-take fishing buffers around several penguin colonies. An expert review found that well-designed closures can support population recovery, but only if sardine stocks rebound across penguin foraging ranges year-round. Following a court-backed settlement, the government has expanded year-round purse-seine fishing closures around six key colonies through at least 2033. This aims to reduce direct competition during the life stages where penguins are most vulnerable. The study’s authors argue that additional measures are still needed. These include ecosystem-based thresholds for forage fish, spatial management aligned with penguin foraging behaviour, and more precautionary harvest rules. The central message is stark. When sardines fall below a critical threshold, adult penguin mortality spikes, breeders vanish from molt counts, and colonies shrink rapidly. Rebuilding prey availability, where and when penguins need it most, is the fastest way to slow and potentially reverse that decline.

Explore ESG Solutions on our marketplace - OneStop ESG Marketplace.

Keep abreast of the top ESG Events on OneStop ESG Events.

OneStop ESG Educate: Your go-to source for top ESG courses and training programs tailored to your needs.

Stay informed with the latest insights on OneStop ESG News.

Discover meaningful career opportunities on OneStop ESG Jobs.