Understanding how past climatic changes affected the great white shark could help improve strategies for conservation and survival in the context of current climate change.

A new study, led by Jaime Villafaña, doctoral student at the Department of Paleontology, University of Vienna, found the oldest known fossil nursery of the great white shark (Carcharodon carcharias). The discovered fossils correspond to the Pliocene epoch (the geological period between 5.3 to 2.6 million years ago), and were found on the coast between northern Chile (between the cities of Coquimbo and Caldera) and southern Peru (city of Pisco). 

The findings shed light on the past distribution of these nursery areas by one of the top predators in today’s oceans. They also highlight the importance of the habitat of this animal, and its success from an evolutionary perspective.

According to Dr. Jürgen Kriwet, Professor at the University of Vienna and one of the authors of this study, Coquimbo represents the oldest nursery area described for the great white shark. 

‘This area contains the highest percentage of juvenile fossils, the lowest of adolescents and a complete absence of mature adults. In addition, there was a high abundance of prey available for the juveniles. In contrast, Caldera and Pisco in Peru were characterised by high percentages of subadult and adult sharks,’ describes Dr. Kriwet.

Lead researcher Jaime Villafaña pointed out that Coquimbo contained mainly juvenile sharks among the fossils, less than 300 cm in length. Comparatively in Caldera and Pisco there were mainly adults. 

“Males longer than 360 cm are considered to be adults, whereas adult females are over 480 cm long. In Coquimbo we found the smallest individual at only 155 cm long, and in Pisco the largest individual measuring 729 cm”, details Villafaña.

Influence of climate change on the great white shark

For Dr Kriwet it is important to improve our understanding of paleo-nursery areas, especially from times when the global temperature was higher, as such time periods can be used as analogues to better project the consequences of current climate change. 

Villafaña says at present the occurrence of the great white shark is uncommon off the Chilean and Peruvian coastline. But fossil evidence shows that these sharks were very abundant in the past.

“The Pliocene is characterized by a reduction in global temperature. Naturally-occurring climatic changes experienced millions of years ago could have influenced the current low abundance of the great white shark in the South American section of the Pacific Ocean. Therefore, understanding how the population of the great white shark behaved facing past climatic changes, could help decision-making regarding the conservation of the species in the context of the current climate change”, comments Villafaña, an associated researcher at CEAZA. 

Dr. Marcelo Rivadeneira, a researcher at CEAZA and also one of the authors of the publication, says changes in climatic and oceanographic conditions could alter the distribution and number of nurseries in the ocean, and that conservation plans need to take it into account. “Our study demonstrates that over evolutionary timescales, nursery areas have been changing, and so we should prepare to face similar changes in the future”.

The results of this research indicate that any future increase of sea surface temperature may favour the shift and establishment of new nurseries in temperate areas, thus re-shaping population dynamics and connectivity of this shark with cascading effects on local food webs.

Nursery areas

Today the distribution of the great white shark reaches most of the planet’s oceans, except the Antarctic and Arctic oceans.This top predator is regarded as a sign of stability in its environment. Despite its role, it is considered vulnerable to extinction due to human impacts. 

The great white shark has a slow growth rate and late fertility, and produce only a few offspring. These animals are born in nursery areas in the ocean, where they are protected against other predators, until they are large enough to turn themselves into ferocious predators. “Such nursery places keep an important and long-lasting effect on the size of the shark population. These areas also influence population distribution and ensure shark survival and its evolutionary success”, Dr. Kriwet explains.

Over the last few years the search for shark nursery areas has increased, as an effort to mitigate the decline of its population. However, the current knowledge about shark nurseries is limited. In this context, paleo-nurseries and its historical features are largely unknown.

“We need to expand the scope of these studies to other areas in the world where it’s possible to find great white shark fossils, including enhanced analysis of the number and distribution of paleo-nurseries at global scale, and comparisons with present conditions. We also need to pin down the exact ages of new fossil findings to reconstruct the paleoenvironment conditions of those areas”, Dr. Rivadeneira adds.

Dr. Rivadeneira asserts that this information is vital to understand whether current oceanographic conditions, which favour the maintenance of present-day nurseries, are the same as in the past.

This research is part of the ongoing doctoral thesis of Jaime Villafaña, at the University of Vienna, funded by the Chilean State programme “Becas Chile”.

Together with Jaime Villafaña, Jürgen Kriwet, and Marcelo Rivadeneira, Catalina Pimiento (Swansea University, UK), Kenshu Shimada (DePaul University, USA), Sebastián Hernández and Alonso Alvarado (Universidad Veritas, Costa Rica) also contributed to this scientific work.