A data storage tag also sometimes known as an archival tag, is a data logger

Data logger

A data logger is an electronic device that records data over time or in relation to location either with a built in instrument or sensor or via external instruments and sensors. Increasingly, but not entirely, they are based on a digital processor...

 that uses sensors to record data at predetermined intervals. Data storage tags usually have a large memory size and a long lifetime. Most archival tags are supported by batteries that allow the tag to record positions for several years. Alternatively some tags are solar powered and allow the scientist to set their own interval; this then allows data to be recorded for significantly longer than battery-only powered tags.

Operation

Data storage tags can have a variety of sensors; temperature, depth, light, salinity

Salinity

Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...

, pressure, pitch and roll, GPS, magnetic and compass. They can be used internally or externally in fish

Fish

Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

, marine animals or research animals. They are also used in other industries such as the food and beverage industry.

At the end of the monitoring period, the loggers can be connected to a computer and the data uploaded for analysis.

Deployment

Archival tags archive data to internal memory. Once they are recovered the data is then extracted by the researcher. The tag is generally mounted to the animal either by cutting a slit into the animal, inserting the tag, and sewing the opening closed. Alternatively researchers externally attach tags to animals by running anchor lines through the tag and into the dorsal fin for most "fish" species. For turtles the tag is epoxied to the shell of the turtle.