Migration of hawksbill turtles Eretmochelys imbricata from Tortuguero, Costa Rica

Abstract

Migration of hawksbill turtlesEretmochelys imbricata from Tortuguero, Costa Rica. Á/ Ecography 28: 394 Á/402.The hawksbill turtle Eretmochelys imbricata is a widely distributed and critically endangered species that feeds on sponges and fills an important ecological role in the coral reef ecosystem. At Tortuguero, Costa Rica, trend analyses indicate considerable decline in nesting estimated at 77.2 Á/94.5% between 1956 and 2003, as a result of excessive turtle fishing. We analyzed flipper tag returns, satellite telemetry and genetic samples to determine movements and habitat use of adult female Tortuguero hawksbills. Tag returns and satellite telemetry show hawksbills migrate to foraging grounds in Nicaragua and Honduras. Genetic analysis indicates the hawksbills may also migrate to Cuban, Puerto Rican, and possibly Mexican waters. We conclude hawksbills represent an internationally shared resource. There is a close correlation between tag recapture sites, hawksbill foraging grounds and coral reef distribution. Caribbean coral reef decline may reduce food availability and negatively impact hawksbill turtles. Conversely, hawksbill decline may shift the balance on coral reefs by reducing predation pressure on sponges and hence make coral reefs less resilient to natural and anthropogenic threats. Strategies aiming to conserve hawksbills and coral reefs must consider both the extensive hawksbill migrations and the close relationship between the species and the coral reef ecosystem.S. Troëng (sebastian@cccturtle.org),

Genetic characterization of eastern Atlantic hawksbill turtles at a foraging group indicates major undiscovered nesting populations in the region

“…* indicates the total number of samples including hybrids with loggerhead turtle haplotypes R, S, T and U. Literature references: Bowen et al, 1996;Díaz-Fernández et al, 1999;Troëng et al, 2005;Bowen et al, 2007b;Browne et al, in press). haplotype network to obtain further insights into the haplotype relationships.…”

“…Therefore to compliment direct tracking, genetic differences based on mtDNA have been extensively used to identify the origins of migratory juveniles using mixed-stock analysis (MSA). This has been applied to hawksbills to study juvenile aggregations and foraging grounds in Australia (Broderick et al, 1994), and the Caribbean region (Bowen et al, , 2007bDíaz-Fernández et al, 1999;Troëng et al, 2005;Blumenthal et al, 2009). The composition of juvenile aggregations may be affected by several factors like nesting population size, oceanic currents, and the natal homing behaviour, where juveniles try to recruit to feeding areas near to their natal rookeries (Bowen et al, 2007b;Bowen and Karl, 2007;Velez-Zuazo et al, 2008;Blumenthal et al, 2009).…”

Geo-political genetics: Claiming the commons through species mapping

“…In contrast, even though Costa Rica contributes only 12% of Cuba A's mixed stock, declined nesting in Costa Rica could support arguments that any take of these turtles, however low the percentage, impacts negatively on Costa Rica's nesting populations. In the latter case, a major decline appears to have occurred 50 years ago, with low level nesting since then (Troëng et al 2005).…”

“…Of the nesting beaches (source populations) sampled in Bowen et al (2007a), nesting in Puerto Rico (Van Dam et al 2008), Antigua (Richardson et al 2006), and Barbados (Beggs, Horrocks, and Krueger 2007) is increasing. Nest trends in Mexico are fluctuating (increasing according to Garduño-Andrade et al 1999); decreasing according to Abreu-Grobois et al 2005), and decreasing in Costa Rica (Troëng, Dutton, and Evans 2005). Nest trends in Cuba and Belize are unknown.…”

Estimating sex ratios in Caribbean hawksbill turtles: testosterone levels and climate effects

“…Genetic work and satellite tracking over the last 15 yr has demonstrated that hawksbill turtles sharing a Caribbean foraging site usually come from distant as well as local rookeries (Bass 1999, Diaz-Fernandez et al 1999, Horrocks et al 2001, Troëng et al 2005, Bowen et al 2007, Mortimer et al 2007, Van Dam et al 2008, Blumenthal et al 2009, Browne et al 2010, Meylan et al 2011, Moncada et al 2012. Initial haplotype data for Anegada suggests that the BVI foraging population consists of individuals from several different source rookeries throughout the Caribbean basin (Godley et al 2004), but enumerating the likely proportion of each would be an important demographic parameter for predictive models of climate change effects.…”