A recent study led by the University of St Andrews has revealed that critically endangered African penguins (Spheniscus demersus) are increasingly competing with commercial fishing vessels for food, particularly during years of low fish abundance. The findings, published in the Journal of Applied Ecology, highlight a significant threat to a species that has already seen its population decline by nearly 80% over the past three decades.
The research introduces a new metric called “overlap intensity,” which measures not only the extent of shared foraging areas between penguins and fishing vessels but also quantifies the number of penguins affected by this overlap. This innovative approach provides crucial insights into how fishing activities impact penguin feeding behavior.
Dr. Jacqueline Glencross, the lead author from the Scottish Oceans Institute, explained, “We wanted a better way to assess how many penguins are potentially impacted when fisheries operate nearby — not just where the overlap occurs.”
Impact of Fishing on Foraging Behavior
The study utilized tracking data from penguins residing on Robben and Dassen Island to analyze foraging patterns. The team, which included researchers from the University of Exeter, the South African Department of Forestry, Fisheries and the Environment, and BirdLife South Africa, found a concerning trend: during years with low fish biomass, approximately 20% of penguins were foraging in areas occupied by active fishing vessels. In contrast, during years of healthier fish stocks, this overlap reduced to just 4%.
These findings suggest that competition for food becomes particularly intense when fish are scarce, posing a greater threat to penguins during critical periods such as chick-rearing. Adult penguins must forage efficiently to provide for their young, making these overlaps with fishing operations especially detrimental.
Conservation Implications and Policy Responses
The study’s quantification of overlap intensity serves as a vital tool for assessing ecological risks and informing ecosystem-based fishery management strategies. It also carries practical implications for the design of dynamic marine protected areas that can adapt to real-time changes in predator-prey dynamics.
Earlier this year, the African penguin gained significant attention due to a landmark court case in South Africa, which addressed the need for biologically meaningful fishery closures near penguin breeding colonies. Following this legal challenge, a high court settlement was reached between conservation and fishing industry sectors, resulting in the South African government reinstating more effective no-fishing zones around Robben Island, one of the key colonies studied.
Dr. Glencross emphasized the importance of these closures, stating, “This research highlights why those closures are necessary. Previously unprotected areas with high overlap intensity are where the penguins were most at risk.”
As the African penguin continues to face existential threats from habitat loss and competition, this research underscores the urgent need for targeted conservation efforts and effective management policies to safeguard the future of this iconic species.
