Endangered crocodiles save aquatic ecosystems

Female Orinoco crocodile from the RFTBS off-site population. Image: Mario Vargas-Ramírez

Did you know top predators, such as crocodiles, play a fundamental role in keeping aquatic ecosystems healthy?

The Orinoco crocodile, one of the largest crocodilian species, is a critically endangered species native to Colombia and Venezuela. Its population has declined to just 250 in the wild due to overexploitation for its skin. Reintroducing the Orinoco crocodile is crucial for its own conservation and the positive cascading effect it will have on protecting other species in the same ecosystem.

Now, thanks to decades of tireless conservation work, captive-bred Orinocos may soon be used to repopulate the region with these vital predators.

"Today, it is widely recognised that top predators, such as crocodiles, play fundamental roles in both aquatic and terrestrial ecosystems.”

Mario Vargas-Ramírez, Universidad Nacional de Colombia

In a bid to save the species, a captive breeding programme was established in 1971 by herpetologist Federico Medem, at the Roberto Franco Tropical Biological Station (RFTBS) in Villavicencio, Columbia. The RFTBS currently houses over 600 Orinocos - making it the world's largest collection of this species. Remarkably, more adult crocodiles might be kept there than in the wild.

Despite the programme's success, reintroducing animals into the wild has been challenging, primarily due to a lack of comprehensive genetic characterisation. This means it is difficult to determine whether the population is genetically viable and free from inbreeding, which can negatively impact the fitness of individuals and the population as a whole.

To ensure successful reintroduction, it is crucial to have a robust genetic assessment to confirm the genetic health and viability of the population. A recent study showed that the captive population has sufficient genetic diversity and is now suitable for reintroduction efforts.

"Today, it is widely recognised that top predators, such as crocodiles, play fundamental roles in both aquatic and terrestrial ecosystems. They significantly impact the nutrient cycle, regulate fish populations, and contribute to important cross-ecosystem engineering processes," explained Professor Vargas-Ramírez.

"The reintroduction of the Orinoco crocodile to the Orinoco region is an urgent priority. Additionally, as the Orinoco crocodile is considered an umbrella species, its recovery and conservation efforts will have a positive cascading effect, protecting a large number of species that coexist in the same environment."

Based on the findings of this study, published in the journal Nature Conservation, the Colombian government, along with other public and private conservation institutions and agencies, can use the individuals identified in this research to initiate the establishment of new populations in regions where the species has been completely depleted.