Migration of Sea Turtles from Caribbean Costa Rica: Implications for Management
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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