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- Troëng, Sebastian
(författare)
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Migration of Sea Turtles from Caribbean Costa Rica: Implications for Management
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Tortuguero National Park in Costa Rica hosts nesting by four species of highly migratory and endangered sea turtles (green, hawksbill, leatherback and loggerhead turtles). Sea turtle research at Tortuguero has been continuous since Dr. Archie Carr began studies in the 1950?s. This dissertation aims to clarify the Tortuguero sea turtles? post-nesting migrations, nesting trends and survival threats. Green turtle nesting at Tortuguero increased with an estimated 417% between 1971 and 2003, partly as a result of conservation efforts. Tag recoveries and satellite telemetry show that post-nesting green turtles migrate to benthic foraging grounds, presumably turtle grass pastures throughout the Caribbean, but some females may feed opportunistically in oceanic waters before initiating migration. During migrations and at the main foraging grounds in Nicaragua, the turtles are caught by fishermen. Annual survival probability estimates for the adult female green turtles, derived from analysis of tag recoveries and recaptures, are lower than for other populations. The reproductive output of the green turtle population may be maintained through shorter intervals between active breeding seasons. The short remigration intervals could be a consequence of abundant food resources, freed up through historical population decline. The hawksbill nesting population has declined with an estimated 77% since 1956. Tag recoveries and satellite telemetry show that post-nesting hawksbill turtles migrate to coral reefs in Nicaragua and Honduras. Genetic analysis indicates the hawksbill turtles also migrate to Cuba, Puerto Rico and possibly Mexico waters. Tortuguero leatherback turtles form part of a stable or possibly slightly declining regional rookery extending at least from Honduras to Colombia. After nesting, the leatherback turtles migrate throughout the Gulf of Mexico and the North Atlantic. The migrations of Tortuguero sea turtles have profound consequences for the setting of conservation priorities and for economic development of coastal communities in Central America. Implications for recovery goals, fisheries, tourism and oil exploration, and the use of protected areas and international conventions as mechanisms to achieve successful management are described.
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| 2. |
- Troëng, Sebastian, et al.
(författare)
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Variation in adult annual survival probability and remigration intervals of sea turtles
- 2007
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Ingår i: Marine Biology. - : Springer Science and Business Media LLC. - 0025-3162 .- 1432-1793. ; 151:5, s. 1721-1730
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Tidskriftsartikel (refereegranskat)abstract
- We analyzed a large dataset to quantify adult annual survival probability and remigration intervals for the Tortuguero, Costa Rica green turtle population. Annual survival probability was estimated at 0.85 (95% CI 0.75-0.92) using a recovery model and at 0.85 (95% CI 0.83-0.87) using an open robust design model. The two most common modes of remigration are 2 and 3 years. Annual survival probability is lower and remigration intervals are shorter than for other green turtle populations. Explanations for short remigration intervals include reproductive compensation due to historic population declines, availability of better quality food items, favorable environmental conditions, and short distance to the main foraging grounds. Variation in survival and remigration intervals have profound consequences for management and life history evolution. The short remigration intervals of Tortuguero green turtles partly offset mortality caused by turtle fishing in Nicaragua and mean that low juvenile survival represents a more urgent threat to the population than low adult survival. Low adult survival probability could result in selective pressure for earlier age at maturity.
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