Tagging Efforts for Sea Turtle Research
Tagging sea turtles around the world to learn more about their migratory patterns, growth rates, survival, and reproductive output.
The researchers in the Marine Turtle Ecology & AssessmentProgram utilize numerous types of tags and methods to track, identify and monitor sea turtles. From flipper tagging nesting females to Passive Integrated transponder (PIT) tags and biotelemetry techniques, these tagging efforts help facilitate research and understanding of sea turtles across species and life stages. Below is a short summary of the different types of tags used by our research program
We use National Band and Tag Company’s Style 681 Inconel Tag. We’ve found these to have the greatest retention and lowest corrosion rates of the various flipper tags we’ve tried in the past. The type of tag we use and the tag applicator can be found here.
Passive integrated transponders (PIT tags) are applied subcutaneously to the fore flipper of a turtle. They have the great benefit of maximum retention, approaching the life of the animal, and low failure rates. These are useful for long-term studies, but are less noticeable than external flipper tags. Thus, for projects hoping for tags to be recovered by other researchers or fishers that encounter tagged turtle, PIT tags are not the best; instead we recommend the use of external flipper tags. The PIT systems we use are manufactured by Avid, Inc. and can be found here.
For tracking individual turtles over long distances or for studying the daily behaviors of sea turtles assemble in foraging areas or near nesting beaches, there are a variety of biotelemetry techniques that we use to study sea turtles around the Pacific. Click here for a summary of MTEAP’s satellite telemetry efforts.
For tracking long distance migration, we recommend the use of platform terminal transponders (PTT), also known as satellite transmitters. These tags employ both ARGOS-linked tracking and GPS tracking technologies. ARGOS tags are most useful for tracking the long-distance migrations of sea turtles, especially when fine-scale movement data are not needed. GPS tags, although more expensive, are a great tool for studying local habitat use and fine-scale movements of sea turtles residing in coastal foraging areas. There are several different transmitter manufacturers that we and our colleagues have had great success with, including Telonics, Inc., Sirtrack, and Wildlife Computers.
Acoustic or ‘sonic’ telemetry is great for tracking of turtles resident to nearshore habitat. The transmission distance of these tags is not the greatest; depending on habitat complexity, water depth, and substrate type, transmissions can be anywhere from 25 m to 1 km. The value of these systems is for on-demand tracking, which enables the research to go into the field and find the turtle whenever they please, assuming the animal is in the study area. Both active and passive acoustic tracking are used for monitoring movements of sea turtles. For active tracking, the researcher uses a hand-held ‘hydrophone’ to monitor the sound emitted from the acoustic tags that are attached to the turtles. In passive tracking, an array of 2 or more stationary receivers are put into the study area and constantly scan for whatever frequencies are being transmitted by the acoustic tags. The two companies that we’ve had great success with are Vemco and Sonotronics, Inc.
VHF telemetry, also known as radio telemetry, is a technique that uses tags affixed to the carapace of turtles that emit a very high frequency radio signal, usually in the range of 148-152 MHz. The value of this technique is that it is a relatively low cost tool that can be easily used in local tracking efforts, and there are some tags as small as 1 g in weight, which allow tracking of very small turtles. However, the drawback is that the precision of locating animals is not the best, and turtles must be at the surface in order for the VHF transmissions to be received. The VHF tracking systems we typically use are manufactured by Telonics, Inc.