Satellite-tracked Migrations by Galápagos Green Turtles and the Need for Multinational Conservation Efforts

Over the last two decades there has been a dramatic increase in the application of satellite telemetry to track the movements of threatened and endangered species. Among the taxa that have benefited the most from these efforts are sea turtles. Every few years, adults of most sea turtle species undertake long-distance migrations between nesting sites and foraging areas; satellite telemetry is an ideal tool for determining where these areas are, and the migratory routes followed by adult turtles as they move between them. More importantly, for conservation purposes, this tool provides a better understanding of the amount of time turtles spend in international waters and economic exclusive zones (EEZs) of various nations, and thus can highlight the potential susceptibility of sea turtles to human impacts (i.e., fisheries bycatch and hunting) that occur in these areas. This understanding is critical for improving conservation measures and maintaining healthy sea turtle populations.

In a recent study by Seminoff et al. (2008), the movements of 12 green turtles (Chelonia mydas) were tracked by satellite telemetry after nesting in the Galápagos Islands. Turtles were tracked for up to 100 days (mean = 64 days) and moved between 75 and 1540 km away from their nesting sites. Three distinct post-nesting migratory strategies were observed, including residency within the Galápagos migrations to Central America, and movements into oceanic waters southwest of the Galápagos.

Green turtles occupied international waters as well as EEZ of Colombia, Panama, Costa Rica, Ecuador and Nicaragua. In two cases, green turtles apparently reached coastal foraging area destinations (in Nicaragua and Panama). As the first-ever satellite telemetry research on Galápagos green turtles, novel insights gained about this insular nesting stock will be useful for the justification and implementation of conservation measures throughout the region. For example, with 10 of the 12 tracked turtles departing the Galápagos after nesting, the results of this study indicate that threats to the Galápagos nesting population, such as bycatch in high-seas fisheries gear, may be much more substantial in overall impact to the population than previously considered. These wide-ranging movements (see Fig.1) underscore the need for conservation efforts to be multinational in scope and multidisciplinary in action.

While no single law or treaty can be 100% effective at minimizing anthropogenic impacts to sea turtles in these areas, there are several international conservation agreements and laws in the region that, when taken together, provide a framework under which sea turtle conservation advances can be made. In addition to protection from the Galápagos Marine Reserve (GMR), green turtles may benefit from the following:
1) the ETP (Eastern Tropical Pacific) Marine Corridor (CMAR) Initiative agreed to by the governments
of Costa Rica, Panama, Colombia, and Ecuador, which is a voluntary effort to work towards sustainable use and conservation of marine resources in these countries’ waters;
2) the Eastern Tropical Pacific Seascape Program managed by Conservation International that supports cooperative marine management in the ETP, including implementation of the CMAR;
3) the Inter-American Tropical Tuna Commission (IATTC) and its bycatch reduction efforts that are among the world’s finest for regional fisheries management organizations;
4) the Inter-American Convention for the Protection and Conservation of Sea Turtles (IAC), which is
designed to lessen impacts on sea turtles from fisheries and other human impacts; and
5) the Permanent Commission of the South Pacific (Lima Convention), which has developed an Action Plan for Sea Turtles in the Southeast Pacific.

The conservation of green turtles in the ETP will require successful implementation and greater integration among the region’s international instruments and accords. New legislation and enforcement of existing laws that curb the flow of turtle products in the region’s coastal communities is also necessary, although it is increasingly clear that any such instruments will only be effective if the underlying human social drivers, such as local demand for sea turtle products or increasing fleet sizes despite lower target species catch rates, are also addressed. By implementing both new and existing conservation measures in an integrated manner, management efforts may be more effective at providing habitat protection that extends from nesting beaches and inter-nesting habitats within the GMR to far off coastal and offshore foraging areas, thereby conserving all life-history phases of green turtles in the ETP.

Originally published as:
Seminoff, J.A., P. Zárate, M. Coyne, D. G. Foley, D. Parker, B.N. Lyon, P.H. Dutton. 2008. Post-nesting migrations of Galápagos green turtles Chelonia mydas in relation to oceanographic conditions: integrating satellite telemetry with remotely sensed ocean data. Endangered Species Research 4: 57–72.

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2008 Jun