April 19, 2016
The use of pronged satellite tags on endangered killer whales has been an important tool for tracking the animals’ movements and determining their critical habitat. But some scientists and naturalists oppose the practice, saying it could be harmful and possibly fatal to some orcas.
The orca was tagged on Feb. 24 off the coast of Washington state, but satellite transmissions stopped three days later, “suggesting premature tag detachment,” NOAA said in a statement. L95’s highly decomposed carcass was found on March 30 near Vancouver Island.
“We are concerned that parts of the tag were found retained in the dorsal fin,” the agency said. “The team has halted tagging activities until a full reassessment of the tag design and deployment is completed.”
According to NOAA, of 533 satellite tags deployed in whales and dolphins in recent decades, only 1 percent are known to have left prongs in animals.
A preliminary necropsy performed by Fisheries and Oceans Canada found no apparent cause of death. A complete necropsy report will be finished in three to four weeks.
Brad Hanson, a wildlife biologist at NOAA Fisheries, said the second necropsy will look for signs of infection. “It could be a possible connection between what was seen internally and the tag site itself, but there was nothing at the tag site to suggest anything going on there,” he said.
NOAA deploys tags to track Southern Resident orcas, which spend much of the year in the Puget Sound area. Their movements have been thoroughly documented while in inland waters, but data on where they go in the open ocean is lacking. The tags are important for determining the full extent of their critical habitat, which is required under the U.S. Endangered Species Act.
Eight Southern Residents have been tagged since 2012, Hanson said. Since the program began in 2004, 66 killer whales have been darted.
Critics contend that tagging is overly invasive and that prongs remaining in the animals can cause harm.
“Not enough thought was given during tag design and development to the issue of tag damage to the whales or whether they would tolerate it,” Ken Balcomb, executive director of the Washington-based Center for Whale Research, wrote in an email. “These whales are endangered, and any stress or injury to them should be avoided, not maximized to facilitate attachment.”
Balcomb noted that two other killer whales, both mammal-eating “transients,” disappeared after being tagged. “T14 was tagged May 18, 2010, and our last photo is in September 2010, maybe he was still alive after that, but he is sure missing now,” Balcomb wrote. “T99A was tagged in July 2010 and our last photo of him is in April 2012.” The disappearances could be coincidental, he said.
He added that darting whales makes them skittish around boats, making it harder to approach some animals for photo identification.
Michael Harris, executive director of the Pacific Whale Watching Association, agreed.
“We have seen NOAA vessels pursuing whales and being extremely aggressive,” said Harris, who called for a permanent ban on pronged tags. “It’s pretty clear it has altered their behavior. Anytime you’re chasing wild animals and sticking things in their dorsal fins, they’re going to avoid you like the plague.”
But Hanson said NOAA researchers had not observed any behavioral changes in tagged whales.
Lance Barrett-Lennard, senior marine mammal researcher at the Vancouver Aquarium, said he noticed changes in behavior during tagging operations in Alaska three years ago.
“The whales did become more elusive,” Barrett-Lennard said. “We couldn’t tell if [it was] because of the pain of the tags or because we had to approach them very closely. Those repeated approaches could have an effect.”
Canada prohibits the use of pronged tags because of their invasiveness. Canadian researchers instead rely on visual sightings and underwater hydrophones to track the whales.