Richard Sherley, Ph.D.

Research

Timothée Cook

Understanding fisheries competition with the critically endangered African penguin

About a third of industrial fishing catches are small pelagic fishes, known as forage fish. These species, which are used to produce animal feed, fish oil supplements, and other products, play a key role in marine food webs by serving as a link between plankton and larger ocean predators. Forage fish populations naturally fluctuate in response to environmental conditions, making it difficult to measure the full impacts of industrial fishing on them or their predators, such as seabirds.

Richard Sherley worked with Ph.D. students and collaborators to explore the relationship between forage fish extraction and population change in the now-critically endangered African penguin. Using a combination of experimental fishing closures, animal-borne data loggers, vessel monitoring data (AIS and catch data), in-colony monitoring, and statistical models, he and his collaborators quantified levels of competition between penguins and their main prey, the local industrial fishery for sardine and anchovy. They documented both behavioral and population-level consequences of fisheries interactions on penguins, which rely on different habitats and prey throughout their life cycle and thus experience varied impacts. The team assessed the potential for penguin populations to change when penguin breeding colonies are in the vicinity of small-scale protected areas that are closed to fishing. The results indicated that such closures could help offset some of the potential negative fishery effects and help to slow and reverse the population decline of African penguins in the long run.

The findings were shared through participation in South African scientific working groups, peer-reviewed publications, interactions with the media, and the International Union for Conservation of Nature’s Species Survival Commission’s Penguin Specialist Group. The findings—particularly the conservation value of the small-scale closures—have been widely debated, and the work has been heavily criticized by some fisheries scientists and fishing industry representatives. Nevertheless, the South African government introduced 10-year purse-seine fishing closures around the six major African penguin colonies in that country in 2023. The efficacy of these closures continues to be debated, and work is ongoing to ensure that their designation and design is biologically meaningful.

To learn more about Sherley, read his bio: https://sites.google.com/view/rbsherley/home.

See the full list of 2019 Pew marine fellows.