Approval has been given for a controversial plan to satellite tag an endangered species of killer whale that frequent the waters off the Pacific Coast.

Researchers hope the tracking devices will reveal the orcas' activities during the winter, but there are concerns from other orca experts that the tagging could harm the vulnerable whales. Southern resident killer whales are one of the most studied marine mammal species in the world, yet very little is known about where they go and what they eat during the winter months and recently the U.S. government gave the approval to attach the tracking devices to the dorsal fins of six whales per season to help better understand what the risk factors during the winter are for these animals and make sure what's necessary to meet the recovery goals that are in the recovery plan. However Ken Balcomb, a senior scientist has seen other killer whales that were tagged off Alaska and is concerned,stating the tags are heavy-duty barbs, and the only way they come off is by tearing away flesh and leaving a golf-ball sized hole.

Mr Balcomb, who has internal infection, like the minor puncture wound that killed a 20-year-old resident whale a few years ago and with these whales living in an urban environment that has a lot of toxins and a lot of problems for their immune and reproductive system, they're especially susceptible to these injuries.The tag is about the size of a nine-volt battery and it would be shot from a cross bow or pneumatic gun into the dorsal fin. The tags can remain attached anywhere from three to nine weeks until they fall out, leaving the wound to heal on its own. The current southern resident population figure is 89, consisting of three separate family pods labelled J, K and L. Spending their summers around Washington state waters and off southern Vancouver Island, they've been spotted as far north as Haida Gwaii and as far south as Monterey, California.

Researchers hope to be able to follow the whales to collect samples of anything left of what the orca?s have eaten and any fecal matter to determine what they've been eating which is mostly salmon. A cross-border scientific panel is already looking into the possibility that limiting the lucrative Chinook fishery could improve the survival rate of the resident population. A decision from the panel is expected at the end of this year.

To date, none of the resident whales have been tagged.