Green turtle

The green turtle, Chelonia mydas, is a marine turtle in the family Cheloniidae, described by Linnaeus in 1758 ^[1]. The global IUCN Red List assessment published in 2025 places it in the Least Concern category ^[2]. In Peru's coastal waters it forms stable feeding aggregations in which individuals stay at the same place for months, such as those studied at El Ñuro and Paracas between 2010 and 2013 ^[3].

Along the Peruvian coast it has been studied in very different settings. El Ñuro, near 4° S, lies in a transition zone between coastal upwelling and warm equatorial water, whereas Paracas, near 14° S, is dominated by upwelling ^[3]. Another study compared the Virrila Estuary, near 5° S and warm all year round, with La Aguada, near 14° S and under upwelling conditions ^[4].

A study of their digestive tracts points to Sechura Bay, in northern Peru, as a feeding area of critical importance for green turtles that have not yet matured ^[5].

At El Ñuro, between 2010 and 2013, sub-adults made up 74.9% of the population, juveniles 15.3% and adults 9.8%; for every adult female there were 1.16 adult males ^[3]. Individuals stayed in the area for between 121 and 1015 days, 331.1 days on average ^[3].

At Paracas, by contrast, 72% were juveniles and 28% sub-adults, and no adults were recorded; residence there ranged from 65 to 680 days, 236.1 days on average ^[3]. At both sites growth rates and body condition indices were high, which points to healthy animals ^[3].

Diet changes with age and place. At La Aguada the turtles were mostly juveniles feeding mainly on animal matter, whereas at the Virrila Estuary sub-adults predominated and their diet was dominated by plant matter ^[4]. The authors propose that juveniles first settle in coastal habitats in southern Peru and, as they grow, move north, where plant food is lower in calories but plentiful ^[4].

In Sechura Bay, the analysis of 67 digestive tracts from two periods, 2001–2004 and 2013–2014, showed that animal prey predominated in the first period and that algae consumption was not related to plastic ingestion ^[5].

In the 2025 global IUCN assessment the species is listed as Least Concern ^[2]. In Peru, the El Ñuro and Paracas aggregations remain threatened by pollution, fisheries bycatch and illegal catch ^[3].

Macroplastic ingestion by turtles in Sechura Bay rose significantly between 2001–2004 and 2013–2014, especially in juveniles, and the plastics found were more frequent and more varied in the recent samples ^[5].

In northern Peru, El Ñuro holds a resident aggregation, where turtles stay for 331.1 days on average ^[3].