Turtle Captures

Once a week we capture both green and hawksbill turtles for tagging and monitoring.

To catch green turtles, we hang carnada, or bait, over the side of a boat right here in the harbor. For bait we use fish heads from the morning market. The big, oily forehead of the dorado (common dolphinfish) is the green turtles' favorite.

Arica prepares to go turtling.

A dorado head.

Waiting around for green turtles to show up.

Workers in the water and on the boat haul in a mature green turtle.

To catch hawksbills we have to put in a little more effort. We snorkel along the rocky coast and sandy beaches, and when someone spots a hawksbill, she keeps her eyes underwater while raising her hand in the air. The boat comes over to help out.

This male hawksbill must have weighed hundreds of pounds.

Vanessa and Cory measure a hawksbill while Arica records data on a plastic cutting board.

In both cases, the turtle capture itself is quite a sight. Our turtle-catching extraordinaire, Luis, leaps onto the turtle from the boat, mask and snorkel already on his face. He uses his left hand on the front of the shell, directing the turtle's movement upwards, and his right hand on the back of the shell, pushing the turtle up into the boat. Depending on the size of the turtle, this maneuver can be simple or extremely difficult.

Dean, an Equilibrio Azul worker, demonstrates the turtle-catching hold.

Once the turtle is on board, we move through our steps as efficiently as possible. We cover the turtle's eyes with a wet cloth to keep it calm, and take measurements of the carapace (top shell), plastron (bottom shell), head, and tail.

Amelia measures the plastron length.

We record the GPS coordinates of the capture.

The GPS lives in a waterproof sleeve.

We check for metal ID tags at the base of each back flipper. If we find tags, we record the numbers to keep a log of where the turtle has been. If there are no tags, we sanitize the flipper with alcohol before attaching some. We also take a small DNA skin sample from the neck of new turtles.

If the turtle isn't yet tagged, we add a metal tag to each back flipper.

We photograph both tags and both sides of the turtle's face as a backup identification method.

You can identify an individual by its unique facial markings.

Finally, we take note of damage, illness, or epibiont organisms before scraping any adhering barnacles off the body and head.

This turtle has a barnacle hairdo.
I'm fascinated by the idea that the turtle's shell constitutes an entire ecosystem with substrate, nutrients, climate, bacteria, plants, and animals. Last semester I completed a research project on the epizoic algae of Galápagos green turtles. I compared carapace algae to the algae which grows on intertidal rocks: in both cases, algae alters the habitat and allows other organisms, including animals, to move in. I wanted to find out how carapace algae relates to cleaning fishes, barnacle load, microbiota, and turtle health. During that project, my partner and I also discovered a previously unrecorded green turtle epibiont species, the Galápagos pencil urchin. Suffice it to say I am interested in sea turtle epibiota!

So, I have been intrigued by the various epibionts we have pulled off green and hawksbill turtles during our captures. We found this little crab hiding under the back lip of a green turtle's carapace, and once we discovered a baby octopus lodged under the shell!

An epizoic crab.

It's a common assumption that barnacles are bad for turtles, and that's why we scrape the bothersome crustaceans off the turtles we capture, but I have never found a scientific paper linking turtle health with algae or barnacle load. I would love to see (or write?) a study on the specific effects of barnacle removal.

This morning before we snorkeled for hawksbills, Luis taught me the art of the turtle capture. Alas, we found no turtles today, so I have yet to try out my skills.

A western painted turtle I caught while camping in Washington State.

As a kid, I proudly earned the nickname of "turtle whisperer" for my ability to catch western painted turtles in the lake where my family went camping every 4th of July. Granted, painted turtles are about 1/700th the size of mature sea turtles (a painted turtle weighs around 1 pound, whereas a green turtle can reach 700 pounds), but I still hope to try my hand as a sea-turtle whisperer one of these days.

The Turtle Whisperer.

In response to my dad's comment... Here are a couple modern examples of turtle whispering.

The upside-down turtle we rescued along the Tiputini River.

I was studying abroad at Tiputini Biodiversity Station in the Ecuadorian Amazon. On our last day, the whole class was moving by motorized canoe to catch a flight, but of course we stopped the boat, backed up to shore, and saved this upside-down river turtle from death-by-dehydration. I love Ecuadorian Time.

My first wild Galapagos tortoise friend.

Here I am with a giant Galapagos tortoise. I had seen a several of these huge reptiles in the Galapaguera, or hatchery, but this was my first sighting of a wild one. (She was surrounded by broken glass, plastic, and a tire. And as you can see from our bus in the background, she was right by a parking lot.) But she was a giant tortoise! IN THE WILD! I was more than a little excited.

Comments

  1. Barnacle hair do ...says the girl with a turtle hair do. I was expecting to see a picture of that side-neck river turtle you guys discovered in the Amazon as well.

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  2. I'm intrigued by the octopus who made her home under the turtle's shell. Indeed a little mobile world! Glad you're continuing your turtle-whispering.

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  3. Here you go, Dad. River turtles and giant tortoises have been added!

    ReplyDelete

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