University of Cambridge

04/30/2023 | Press release | Distributed by Public on 04/30/2023 04:20

The mystery of Robinson Crusoe's seals

Journey to Robinson Crusoe's island

Constanza Toro-Valdivieso was studying to be a vet in her home country of Chile when she first read about the fur seals of Juan Fernández.

The archipelago is probably best known for the story of Alexander Selkirk, a Scottish privateer marooned there from 1704 to 1709 whose story is thought to have inspired Daniel Defoe's 1719 novel The Life and Strange Surprizing Adventures of Robinson Crusoe of York, Mariner. In the hopes of boosting tourism, the Chilean government decided to rename the three islands Alejandro Selkirk, Robinson Crusoe and Santa Clara in the 1960s.

Today, this one-time pirate hideout and penal colony is home to one of the least known species of fur seals on the planet.

But reaching them is no small matter. On her 7,600 mile journey from Cambridge to Robinson Crusoe Island, Constanza has met with leaky boats, bad weather and closure of the islands for fire risk.

Why study the fur seals? Because this knowledge would be a valuable contribution to monitoring and managing the protected marine ecosystem around the islands, says Constanza from Cambridge's Department of Veterinary Medicine.

"Even though Juan Fernández has been identified by UNESCO as being important for its biodiversity, resources for observing and enhancing conservation in the region are scarce," she explains.

"Identifying and studying 'charismatic' species like fur seals can have an essential role in promoting awareness and action. But information on the fur seals is limited and outdated. I wanted to create a 'benchmark' of their health so that we can measure changes in the future."

And the benefits extend beyond protecting the fur seal population to protecting the health of our seas.

"Because these are marine animals, their health tells us about the oceans they inhabit, like a sort of 'canary in the coalmine' of the seas. For instance, warming of the seas by climate change affects abundance of prey and mating behaviour."

Marine pollution is another critical factor...

"A few hundred miles to the west of the Juan Fernández archipelago is a huge area of plastic contamination 18 times the size of the UK."

"We know that plastic debris, which can be may be micro- or even nano-sized, absorbs toxic heavy metals such as cadmium and mercury released into the seas by human activities like mining and oil extraction.

"We also know that marine mammals can be highly exposed to heavy metals particularly if, as fur seals do, they feed on species like octopus and squid.

"Although the Juan Fernández fur seals live in an almost pristine environment, their foraging grounds coincide with the area of plastic pollution. What effect, we wondered, would this have on them?"