image:

Large chick

Credit: Jacqui Glencross

A recent investigation led by the University of St Andrews has revealed that critically endangered African penguins (Spheniscus demersus) are far more likely to forage in areas used by commercial fishing boats during years when fish populations are low. This increases food competition and places additional stress on a species already facing severe decline.

The findings, published today (17 November) in the Journal of Applied Ecology, introduce a new method called “overlap intensity.” This approach doesn’t just measure the shared space between penguins and fishing fleets but also evaluates how many penguins might be affected within this overlapping zone.

Over the past thirty years, the African penguin population has dropped by nearly 80%. A significant factor in this decline is the competition for essential prey species like sardines and anchovies, which are also targeted by commercial fisheries in the region.

These fisheries primarily use purse-seine nets — large circular nets that enclose schools of fish — to catch their targets.

Dr Jacqueline Glencross, the lead researcher from the Scottish Oceans Institute at the University of St Andrews, explained: “We aimed to better estimate how much of the penguin population might be affected when fishing boats operate close by — not just where that interaction happens.”

The researchers, working with experts from the University of Exeter, South Africa’s Department of Forestry, Fisheries and the Environment, and BirdLife South Africa, analyzed tracking data from penguins located on Robben and Dassen Island. In 2016, a year marked by low fish availability, around 20% of the tracked penguins were using the same foraging zones as active fishing vessels. In contrast, during more abundant years, this overlap dropped to approximately 4%.

The results indicate that competition between penguins and fisheries becomes especially intense when fish is scarce, particularly during sensitive periods such as chick-rearing, when adult penguins must gather food effectively for their offspring.

By assessing population-wide overlap intensity, the study offers a valuable method for gauging ecological risk and providing input for fisheries management based on ecosystem needs. This research could also aid in creating adaptive marine protected areas that react in real time to changes in predator-prey behavior.

Notably, African penguins were recently at the center of a major legal ruling in South Africa. The case questioned the lack of meaningful fishing restrictions near penguin breeding grounds.

Earlier this year, a legal agreement between conservation groups and the fishing industry led to new no-fishing zones around key colonies such as Robben Island. These restrictions aim to create safer foraging conditions for penguins.

Dr Glencross noted: “Our findings support the necessity of those no-fishing zones. Previously unprotected areas showing high overlap intensity represent the greatest risk to the species.”

ENDS

Journal

Journal of Applied Ecology

DOI

10.1111/1365-2664

Method of Research

Data/statistical analysis

Subject of Research

Animals

Article Title

Spatial overlap alone downplays the level of interaction between a central place forager and the local fishery

Article Publication Date

17-Nov-2025