Fast Growing, Healthy and Resident Green Turtles (<i>Chelonia mydas</i>) at Two Neritic Sites in the Central and Northern Coast of Peru: Implications for Conservation

<div><p>In order to enhance protection and conservation strategies for endangered green turtles (<i>Chelonia mydas</i>), the identification of neritic habitats where this species aggregates is mandatory. Herein, we present new information about the population parameters and residence time of two neritic aggregations from 2010 to 2013; one in an upwelling dominated site (Paracas ∼14°S) and the other in an ecotone zone from upwelling to warm equatorial conditions (El Ñuro ∼4°S) in the Southeast Pacific. We predicted proportionally more adult individuals would occur in the ecotone site; whereas in the site dominated by an upwelling juvenile individuals would predominate. At El Ñuro, the population was composed by (15.3%) of juveniles, (74.9%) sub-adults, and (9.8%) adults, with an adult sex ratio of 1.16 males per female. Times of residence in the area ranged between a minimum of 121 and a maximum of 1015 days (mean 331.1 days). At Paracas the population was composed by (72%) of juveniles and (28%) sub-adults, no adults were recorded, thus supporting the development habitat hypothesis stating that throughout the neritic distribution there are sites exclusively occupied by juveniles. Residence time ranged between a minimum of 65 days and a maximum of 680 days (mean 236.1). High growth rates and body condition index values were estimated suggesting healthy individuals at both study sites. The population traits recorded at both sites suggested that conditions found in Peruvian neritic waters may contribute to the recovery of South Pacific green turtles. However, both aggregations are still at jeopardy due to pollution, bycatch and illegal catch and thus require immediate enforcing of conservation measurements.</p></div

Green turtle (<i>Chelonia mydas</i>) neritic aggregations at two sites along the coast of Peru.

<p>(A) El Ñuro, at the northern part of the Peruvian coast, a region characterized by the convergence of the Humboldt upwelling ecosystem and the warm Equatorial ecosystem and (B) Paracas, characterized by permanent upwelling in the central coast of Peru. Map was created using Maptool available at <a href="http://www.seaturtle.org/maptool/" target="_blank">www.seaturtle.org/maptool/</a>.</p

Size, preliminary growth rates, and body condition index of green turtles (<i>Chelonia mydas</i>) at foraging grounds in the eastern Pacific.

<p>Information includes site name, samples size (n), proportion of juveniles to adults (Juv∶ Adt) reported either as a percentage or as total count of samples individuals, mean and standard deviation (SD) of curve carapace length (CCL), straight carapace length (SCL) in cm, weight in kg, growth rate in cm year⁻¹, and body condition index (BCI). We include information of the habitat and the size criteria to distinguish juveniles from adults (mean nesting size-MNS of females).</p><p>Size, preliminary growth rates, and body condition index of green turtles (<i>Chelonia mydas</i>) at foraging grounds in the eastern Pacific.</p

Box plots of (A) curve carapace length, (B) straight carapace length and (C) body weight of green turtles at both study sites.

<p>Box plots of (A) curve carapace length, (B) straight carapace length and (C) body weight of green turtles at both study sites.</p

Size (CCLn-t) distribution of green turtles captured at (A) Paracas and (B) el Ñuro.

<p>Dotted lines are the minimum and mean size reported for adult green turtles in Galapagos Island <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0113068#pone.0113068-Marquez1" target="_blank">[36]</a>, the largest green turtle rookery near Peru.</p

Box plots of body conditions values per green turtle life stages at the different sampling years at El Ñuro (grey boxes) and Paracas (white boxes).

<p>Box plots of body conditions values per green turtle life stages at the different sampling years at El Ñuro (grey boxes) and Paracas (white boxes).</p

Number of times (%) that each turtle classified as juveniles (dark gray bar), sub-adult (light gray bar), or adult (white bar) was recaptured in El Ñuro and Paracas.

<p>The total number of turtles caught is indicated on top of each column.</p

Relationship between weight and growth rate (A) and length (SCLn-t) and growth rate (B) for foraging aggregations of green sea turtles in the eastern and central Pacific (black dots), including our study (green dots).

<p>Relationship between weight and growth rate (A) and length (SCLn-t) and growth rate (B) for foraging aggregations of green sea turtles in the eastern and central Pacific (black dots), including our study (green dots).</p