History of Turtle Tagging

You can only do so much with a nesting turtle to study it. Weigh it. Measure it. Count the number of eggs. Describe it. But that isn’t enough. Dr Archie Carr was familiar with tagging birds and other animals for research purposes. So he talked to his brother Tommy, the physicist in the family, and came up with some sort of nickel alloy that was resistant to seawater. Punch four holes in the shell, stick nickel wire through the holes and wire the tag on. Now, the cow ear tag is used which is crimped onto the fleshy part of the trailing edge of the fore flipper.

The tags say “Reward. Premio.” and have the address of the department of biology at the University of Florida. The idea was that fishermen who caught the turtles would report them in order to collect their reward. In So excellent a fishe: A natural history of sea turtlesSo Excellent a Fishe, Archie records letters that he had gotten from local fishermen. Most are to the effect of, “Ah good sirs, if the Lord has been kind to you and it has been a good day, then please could you remember the reward you promised for fishing out a turtle…”

Once Archie started tagging turtles, he could start collecting information on growth rates, site tenacity, and population recruitment. Site tenacity is how often a turtle will come back to the same beach, and population recruitment is how many new turtles come to a beach. An interesting trend was noticed. The same female would return to the beach several times in a season and then some seasons not return at all.

There was a Caribbean lore which said that the turtles come and the turtles go. Archie Carr wanted to know where the turtles were going. The navy was extremely interested in tracking turtle movements for research on animal navigation. Archie received several grants from the navy as well as help from navy personnel. After several failed attempts, Archie devised a way to track turtles:

Attach a weather balloon to the turtle, and build two towers. Every two minutes for the next twenty hours, record the bearing of the turtle’s location. With the two towers, the turtle’s position could be triangulated. Interestingly, the turtles rarely dove below fifteen feet unless frightened. Archie found out that the turtle goes out and mates with new males, and then comes back to lay a new clutch. This was a breakthrough discovery.