Although a lot of research is and has been conducted on sea turtles in the past 30 or so years, it is relatively new in terms of scientific study.  Many other creatures have been studied over a lot longer span of time, so a lot more is know about them, yet there are so many things still to be learned about sea turtles.  Sea turtles are long-lived species, who don’t reach maturity until late in life.  They are solitary, highly migratory animals who spend their entire lives in the ocean (only exception being when the females come ashore to lay their eggs).  These elements make studying them very difficult.

One way of monitoring the nesting sea turtle population is through saturation tagging using flipper and/or PIT (Passive Integrated Transponder) tags (see beach monitoring).  But these methods exclude juvenile and male sea turtles, not to mention they give us limited information on movement, only indicating which areas the turtles are using for nesting purposes.  Satellite transmitters on the other hand give us a whole new perspective on sea turtle movements and behavior.  They can be placed on juveniles, sub-adults and adults, both male and female, alike.  Satellite tracking enables us to follow their movements, get a glimpse of where they go during the various life stages and during different seasons, and through interpretation of the data, we can assimilate behavior.  This valuable information is a major contributor towards the current research, understanding and conservation of sea turtles.

The GSTC staff has placed satellite transmitters on 17 loggerhead sea turtles and 1 green sea turtle since opening in 2007. Click here for a complete list of satellite tagged sea turtles and their tracking maps!

A Satellite Tracking and Analysis Tool (developed by Michael Coyne and BJ Godley at seaturtle.org) allows us (and YOU!) to monitor the journey these animals take.  The information received from the satellite transmissions are posted on a tracking map and the text provides information about each turtle and the project/facility they come from.

Interpreting the data and maps can be a bit tricky. When something seems unusual, we will usually post a BLOG about it, explaining what’s going on (to the best of our knowledge and interpretation).  But basically, a satellite transmitter can last a few days or a few years.  There are a lot of factors and variables that dictate how long and how well a satellite transmitter will work.  First and foremost, the transmitter ONLY sends a signal when it breaks the surface of the ocean. Depending on how long it is at the surface, where the satellite(s) is, and how many are in range, will determine the type of signal (see below for more).

Battery:

The battery is similar to your cell phone battery.  When not ‘in use’ (aka the turtle is not on the surface), it doesn’t use up a lot of energy. However, when the turtle is at the surface and transmitting a signal it is using up battery power.  Now, if a turtle nests multiple times in a season, her battery will easily get burnt out.  Go back to the cell phone analogy…when your phone is on ‘roam’ and searching for a signal, it burns up your battery pretty quickly.  The same sort of thing is happening to a satellite transmitter on a nesting turtle. While she’s on land for 1-2 hours PER NEST, her transmitter is just shooting up signal after signal.  Each nest she lays could potentially use up 3-4 months of battery power!  Remember also that batteries can not only lose power, but can also malfunction.

Signals:

There are different types of signals or ‘hits’ received by the satellite transmitter, 8 to be exact: 3,2,1,0,A,B,X,Y,Z.  They range from very low or poor-quality ‘hits’ (0,B,X,Y,Z) to excellent, very high-quality ‘hits’ (3,2,1,A).  The lower-quality ‘hits’ don’t give us a location (i.e. GPS coordinates), but rather just let us know the transmitter is still working.  Often these types of ‘hits’ will be received when a turtle is spending very little time at the surface, maybe he/she is doing a lot of deep diving often seen while feeding or travelling and/or migrating or there could be bio-fouling on the transmitter from the environment the turtle is in, like a salt marsh that has a lot of silt, marsh grass, etc., that is blocking the transmitter’s signals.  These ‘hits’ are not plotted on the tracking maps, as they are not very accurate and there are no associated GPS coordinates to map!  The good-quality ‘hits’ on the other hand are the ones you see on the tracking maps, with accurate GPS coordinates associated with them.  Now although B ‘hits’ aren’t all that good, they are better than 0,X,Y,Z and if a turtle hasn’t given us very good signals in a while, but maybe a B here and there, we can manipulate the map to show these points to give you an IDEA of the turtle’s current general location, but be cautious of their accuracy!

Why don’t we go out and get/help the turtles when they stop transmitting?

Eventually each transmitter will stop working at some point, for some reason.  Whether it is a battery-related issue, a malfunctioning transmitter, removal of the transmitter (some turtles like to scratch their backs, or carapaces, and can sometimes dislodge the transmitter or the fixing agent-marine epoxy, etc.-can degrade due to the saline conditions), or an untimely death of a turtle.   But more often than not, if you see a turtle has stopped transmitting, it is probably a transmitter or environment problem, not something wrong with the turtle. To go out after a turtle is just not feasible.  Not only are resources a problem, but finding a solitary, highly migratory turtle in the very large ocean is a nearly impossible venture–sort of like finding a single, specific straw of hay in Iowa!

Costs:

Satellite tracking can be expensive, with each transmitter costing ~$2,000-$3,000.  After placement on a turtle and release, we still have to pay for satellite time and data management, totaling approximately $6500 minimum PER TURTLE.  The longer the turtle transmits good signals, the more it will cost. Funds generated through the Adopt-a-Sea-Turtle Program assist with not only the care, feeding and maintenance of the sea turtles while in our hospital, but also the purchase of these satellite transmitters for those that meet the necessary criteria and the associated costs after release.