Caught in a Deadly Dilemma: African Penguins Battle Hunger and Industrial Nets with Every Dive

The ocean seems vast, but it is no longer enough to protect those who depend on it for their livelihood. When resources become scarce, trajectories tighten, predators and trawlers cross their paths more and more often. For African penguins, every detour can become a dead end. Their fragility is expressed in this invisible tension between reproduction, migration and access to food. A tension that is now measurable, and which threatens their very survival.

Increasingly unpredictable fish stocks

The survival of African penguins depends on a fragile balance. These seabirds, endemic to the South African coast, must feed their young from very specific prey. Mainly sardines and anchovies. However, these pelagic fish are also the main targets of industrial fishing operated by purse seine, a giant net capable of encircling entire schools. When there is abundance, everyone gets their share. But during years of shortage, everything changes.

In 2016, the biomass of young anchovies recorded off Cape Town fell to 327,898 tonnes, more than half the average observed over the previous three decades. Fish, fewer in number and more dispersed, become more difficult to locate, both for birds and for fishermen. As a result, everyone converges on the same pockets of resources. It is precisely this convergence that worries ecologists. A year later, when the abundance of anchovies exceeded 2.5 million tonnes, cohabitation was suddenly reduced.

When African penguins cross the paths of trawlers

Until now, measuring the interaction between penguins and fishing was based on a simple map. We were just identifying areas of overlap. But this approach remained partial. A team from the University of St Andrews, in collaboration with South African and British researchers, has just introduced a much more revealing indicator. In their study published in September 2025 in the Journal of Applied Ecology, the scientists modeled not only the areas where birds and ships meet, but above all the number of individuals affected by these encounters.

This new index, called overlap intensity, changes the situation. It reveals that, even if the area of ​​overlap remains limited, the density of interaction can be critical. In 2016, approximately 20% of penguin journeys spatially coincided with fishing activities. In impact intensity, this was equivalent to 83% coverage. In other words, almost all fishing efforts were concentrated in areas used by a significant proportion of birds, during the chick feeding period.

These figures are all the more worrying as GPS monitoring of several hundred penguins confirmed the data, supplemented by colony-scale modeling. This approach has highlighted hotspots of competition, notably northeast of Robben Island, where vessels tap into fish migration corridors before birds can even venture there.

A decisive tool for rethinking marine protection

This sudden convergence in space has a multiplied effect on a species already on the verge of extinction. The African penguin population has fallen by 78% in thirty years, and their ability to raise their young depends on rapid and efficient access to food. However, any disruption of this access can compromise an entire breeding season.

According to IFLScience, in the face of this pressure, political measures are beginning to emerge. In South Africa, no-fishing zones have been tested around certain colonies, such as those of Dassen and Robben Islands. These temporary closures made it possible to observe an improvement in the physical condition of the chicks. But current protections do not cover all risk areas. The Glencross study shows that certain very exposed pockets are not included in the protected perimeters, even though they concentrate a high rate of interactions.

The implementation of dynamic marine protected areas, capable of adjusting to annual variations in biomass or fish migrations, is becoming a tangible prospect. Thanks to satellite monitoring data and the measurement of overlap intensity, it is now possible to anticipate areas of conflict between fishing and marine predators. On condition that political will accompanies scientific tools.