Researchers from the British Ecological Society studied an endangered African penguin colony during a three-year closure of commercial fisheries around Robben Island, South Africa. The team found that local fish abundance directly affects how adult penguins fish and the body condition of their chicks.
One of the biggest drivers of biodiversity loss in the ocean is fishing, which is so widespread that it prevents us from understanding the “natural” relationships between predators and their prey. Many marine predators like penguins are species whose success indicates the condition of their habitat, also known as indicator species.
“Understanding how African penguins forage to feed their chicks in their variable marine environment can help us identify conservation measures for these endangered populations,” said study lead author Dr. Kate Campbell. “A three-year commercial fisheries closure around Robben Island, South Africa created a unique opportunity to study how African penguins directly respond to natural changes in local abundance of their prey – anchovies and sardines.”
The study revealed that local abundance of anchovy and sardine populations were directly linked to African penguin foraging behavior and the condition of chick offspring.
When fish abundance was lower, adults were seen swimming further, foraging for longer, and diving more often. This explains why chick body condition declined, as breeding adults were dedicating more energy to finding food.
“Interestingly, the variation in foraging behavior between individuals also increased when prey fish were scarcer,” said study co-author Dr. Richard Sherley. “While some ‘superstar’ penguins find food easily, others are less successful. Once food gets harder to find, more individuals will start to struggle and work harder, but they will do so at different rates, increasing the variation we see in foraging effort.”
The study findings suggest that penguin foraging behavior and chick condition could be key indicators for local fish abundance.
“Since these short-term changes will likely have knock-on effects for chick survival and penguin population size, they could be used as powerful early warning signs to inform fisheries’ policies and marine conservation efforts,” said Dr. Campbell. “Technological advances also means there’s exciting potential to better understand how these endangered penguins behave when prey resources are scarce.”
“Hopefully, in the future, we could aim to effectively balance fishery management with penguins’ needs, to reduce the impact on local economies whilst maximising the benefits to our oceans,” concluded Dr. Sherley.
The study is published in the Journal of Applied Ecology.
By Chrissy Sexton, Earth.com Staff Writer
Image Credit: R. B. Sherley