Researchers from the National Oceanic and Atmospheric Administration (NOAA) have tagged killer whales, as part of an ongoing project, to establish their winter travel routes and preferred waters.

The scientists believe the tagged whales (Southern Resident Killer Whales) will help provide information about their location, choice of prey and other data useful in the fight to conserve the species.

The current project has been going for about seven years now. Unfortunately, even over so long a period, the amount of information they received was inadequate; it is hoped the satellite tracking method will provide more data.

The tag has a transmitter (which is about the size of a standard 9-volt battery) that sends a signal - when the whale is at the surface of the ocean - to an orbiting satellite. The signal then bounces off that satellite to the System Argos receivers mounted on NOAA's polar orbiting weather satellites. When tag transmissions are received by these satellites, these signals are then sent to a ground station where researchers can track location and other details.

The researchers did stress that while there was a risk of the whales injuring themselves during the tagging process or afterwards, there was very little chance they could suffer serious or mortal wounds.

The animals will only be tagged between early winter and spring - late December through April - in order to determine winter movements. The tagging will also only take place on coastal surveys and be timed to maximize chances for follow up/sample collection on NOAA ocean-class vessel surveys or other survey efforts. Researchers say only adult whales (like post-reproductive females and adult males) will be tagged.

The tags and darts have been re-designed following a small number of attachment failures in 2010; the tags tended to break on impact. The re-designed tags have been thoroughly tested.

On a negative note, the practice of satellite tagging marine mammals is controversial because the tag harms the dorsal fins and can cause some de-pigmentation on the whale's skin.