Tracking Sea Turtles on the Galapagos Islands

Satellite signals from halfway around the globe provide a wealth of information for Alma students analyzing data in the Dow Digital Science Center.

Faculty biologist John Rowe dons his snorkeling gear, dives into the warm Ecuadorian waters off the Galapagos Islands and searches for sea turtles that may weigh as much as 250 pounds in order to attach satellite tracking devices.

Once discovered and subdued, a turtle is outfitted with a GPS unit on top of its shell using a marine epoxy. The durable tracker unit has an antenna, which transmits a signal to a satellite enabling the turtle’s movements to be tracked for as long as 18 months.

The information from the transmitted signal is relayed to an ARGOS website, an online GPS data collection system dedicated to studying and protecting the environment. The data is then fed into the Dow Digital Science Center at Alma College, where students and faculty can download the data in various forms for purposes of research and education.

Tracking turtle movements

Rowe’s research partners, Juan Pablo Munoz and Daniela Alarcon of the Galapagos Science Center, have been tagging female sea turtles for several years. The longest migration he has tracked has been a turtle’s movement from Galapagos to mainland Central and South America.

“We don’t know how male turtles move,” says Rowe, the William R. Angell Professor in Biological Sciences at Alma College. “Females typically move from foraging grounds to nesting beach areas. But males may not do that; we don’t know what they do.”

With grant funds provided by The Herbert H. and Grace A Dow Foundation, Rowe purchased GPS units for an Alma College tracking project involving male green sea turtles.

“These are critically endangered and protected animals,” says Rowe. “So it is important to know their movements and reproductive behaviors for conservation reasons.”

Turtles with Color Variants

There are primarily two types of green sea turtles that can be found in the Galapagos Islands: Eastern Pacific green sea turtles that reside along the western shores of the Americas, and the Western Pacific green sea turtles that normally dwell in Hawaii, Polynesia, Thailand and Australia.

The Eastern Pacific turtles tend to be black in color, often associated with volcanic beaches, like those found at the Galapagos. The Western Pacific green sea turtles are yellow-green in color; they tend to live in coral reef habitats. Yet, turtles with these color variants are occasionally seen together in the Galapagos. Where did they come from, and how did they get there?

Last March, Rowe’s team tagged the first-ever male green sea turtles with GPS units.

Invaluable Data for Research

“We are getting multiple readings every day,” says Rowe. “We also tagged a rare male Hawksbill turtle, the first-ever caught in Galapagos. The data received from these turtles will be invaluable for researchers to learn more about their movements.”

Rowe and his students plan to return to Ecuador to tag more turtles.

GPS transmitters are not the only kinds of data-collection units that can be attached on turtles. Last summer, the Alma team tagged turtles with sensors that record water depth, time in water, and water temperature.

“We can see how that data varies in the seasons,” says Rowe. “These are extremely interesting data, all available for students and researchers at the Dow Digital Science Center.”

Story published on June 13, 2016