- Eastern Pacific Leatherbacks follow predictable routes when migrating from coastal breeding sites to feeding areas at sea.
- Knowing their locations allows conservationists to implement specific and targeted measures for their protection.
- Leatherbacks could be extinct in the eastern Pacific Ocean within the next century if efforts are not made to ensure their survival.
Science is the basis for all CI work and initiatives. The Sea Turtle Flagship Program is no exception. From studying beach nesting sites to tagging sea turtles with satellite tracking devices, we seek to gain an accurate picture of what these animals do, where they go and how we can better protect them on land and at sea.
Why Study Leatherbacks and Their Habitats?
Although it is relatively easy to study sea turtles on land while they lay their eggs, it is difficult to study their behavior at sea because their migrations and movements can span entire ocean basins. Sea turtles spend the vast majority of their lives in the ocean, making an understanding of their ecological needs in ocean habitats essential to sound conservation strategies.
Leatherback sea turtles are particularly important because their ocean migrations cross national and international boundaries. This means they provide an important opportunity for multiple governments, international and local NGOs and other stakeholders to work cooperatively in the name of conservation.
The Research Project
The Leatherback sea turtle population in the eastern Pacific Ocean has declined more than 90 percent over the past two decades due to the unsustainable harvesting of turtle eggs and fishery “bycatch” – a term that refers to the accidental catching of animals like sea turtles, seabirds and marine mammals in nets and traps meant for other marine species such as tuna and swordfish.
LEARN MORE: Explore more threats to leatherback sea turtles.
Recently, a team of international scientists, government administrators and conservationists published a study that explained and examined the long-distance migrations of Leatherbacks from Costa Rica to the southeastern Pacific Ocean. The researchers tracked 46 females over a four-year period – the largest multi-year study of Leatherback sea turtles – and in doing so learned a great deal about the mysterious life of these creatures on the high seas. This work, supported in part by CI’s Global Conservation Fund (GCF)*, has resulted in a bold proposal for protecting leatherback sea turtles, based on the turtles’ own recorded habits.
Migration Habits and Patterns
The Leatherbacks that were studied spend about 60 days around their nesting beaches on the Pacific coast of Costa Rica. After laying their eggs, they depart the breeding area and begin a long-distance migration to feeding areas more than 8,000 km (4300 mi) away and remain at their feeding areas from two to seven years. Unlike Leatherback populations in other parts of the world, it appears the Eastern Pacific Leatherbacks’ migratory patterns are consistent both in where they go and how they get there.
|Turtle migration routes (red) near the Galapagos Islands for February-April periods of 2004, 2005 and 2007|
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The results of the tracking indicate that the sea turtles followed a predictable route with a specific direction in mind. Despite having to cross several currents, often flowing in opposite directions across the equator, they are able to avoid being blown off course.
But this doesn’t mean that these sea turtles travel in a large, orderly pack. Because of the varied strength of the ocean currents, the sea turtles can be dispersed through the ocean. For example, the currents in 2007 were stronger than those in 2005, resulting in a wider spread of sea turtle tracks through the region. By excluding the influence of the currents, the researchers were able to highlight the sea turtles’ ability to navigate through complex regions of the ocean year after year, indicating that they possess some degree of directional sense. This may be guided by geomagnetic forces, as has been documented for sea turtles in other parts of the world and for other migratory animals.
How and When Leatherbacks Migrate
|Leatherback migration route (green) |
through the equatorial current system
These new discoveries on Leatherback behavior and migration are not just interesting from a scientific perspective. They also have important applications for conservation.
The migration route occurs between February and April and is mostly within the Eastern Tropical Pacific Seascape. Such specific times and places allow conservationists to tailor their recommendations for the management of Leatherbacks and their habitats.
One tactic is the use of "dynamic time-area closures": Fishing operations are restricted in the areas that are used regularly by Leatherbacks while they are there, but are open at all other times of the year.
This strategy is designed to keep fishery boats and sea turtles far apart, while still allowing both to do what they need to do. This approach is currently in place in California- and Oregon-based fisheries, and no leatherback bycatch has occurred since its implementation.
Although this study reported the largest tracking dataset ever recorded for Leatherbacks, the data only represented the beginning of the non-reproductive period for female leatherbacks. Therefore, much more research is needed to fully understand leatherback behaviors and habitat use at sea.
The evolutionary lineage of leatherbacks stretches back 100 million years, yet they could be extinct in the eastern Pacific Ocean within the next century if efforts are not made to ensure their survival. Sea turtle experts at Conservation International and all over the world will build on these important results with further research and will continue to study these marine creatures in order to guide conservation programs.
IN DEPTH: Study the data for yourself by downloading the full report (PDF - 707 KB).
Citation: Shillinger GL, Palacios DM, Bailey H, Bograd SJ, Swithenbank AM, Gaspar P, Wallace BP, Spotila JR, Paladino FV, Peidra R, Eckert SA, Block BA. (2008) Persistent leatherback turtle migrations present opportunities for conservation. PLoS Biol 6(7): e171.
*For a full list of funding sources, download the report (PDF - 707 KB).