Tagging of Pacific Predators - Tagging

Tagging

Many different types of tags are used in the TOPP tagging program, each designed for different marine animals and different types of data. Archival tags, though small, are very powerful, and can last up to 10 years. Researchers surgically implant them into the bellies of tuna, where the tags record, as often as every few seconds, pressure (for depth of dives), ambient light (to estimate location), internal and external body temperature, and, in some cases, speed of travel. The tags are small and light enough to be attached to the outside of an animal, such as the tail feathers of red-footed boobies. However, they do have a drawback, they have to be retrieved. So, they are useful for fish likely to be caught as seafood, such as bluefin or yellowfin tuna, or animals that return to rookeries or nesting beaches, such as boobies and leatherback turtles.

Pop-up satellite archival tags (PSATs), also known simply as pop-up archival tags (PATs), are just like archival tags, except they are designed to release at a preset time, like 30 days. They then float to the surface and send their data via an Argos satellite back to the laboratory for two weeks, which is the life of its battery. Even when the battery dies, the data are saved on the tag, so if it is ever recovered, the whole data set can be downloaded. This tag is useful for animals that do not spend a lot of time at the surface, and are not caught often. Numerous white sharks have been tagged with this tag. The tags are attached to white sharks by inserting a small surgical titanium anchor into it. On elephant seals, the tag is glued to the fur. Connecting the tag to the anchor is a thin line that loops around a metal pin at the base of the tag. This metal pin is connected to a battery. A clock in the tag turns the battery on at a preprogrammed time. When the battery turns on, the attachment pin dissolves. The tag floats to the surface and starts transmitting data to one of the Argos satellites.

Spot tags, or smart positioning, or temperature transmitting tags, are ideal tags for air-breathing marine animals (seals, whales and sea turtles) and animals that often swim close to the surface (salmon sharks, blue sharks and makos). When the antenna breaks the surface, it sends data to a satellite. The data include pressure, speed, and water temperature. Location is estimated by calculating the Doppler shift in the transmission signal in successive transmissions. When the animal goes beneath the surface, a saltwater switch turns off the tag. The tag, made by Wildlife Computers, lasts about two years.

Satellite relay data logger (SRDL) tags compress data so more information can be transmitted through the Argos satellite. These can be outfitted with CTD tags to record the salinity, temperature and depth data oceanographers need to identify ocean currents and water. Elephant seals, sea lions and leatherback sea turtles wear these tags.