SEATTLE — A team of marine mammal biologists and veterinarians from the United States and Canada is treating and monitoring a gray whale that appears to have developed an infection several months after being darted with a satellite tracking tag.
The whale is part of a group of about 250 gray whales that feed off the coasts of Oregon, Washington and British Columbia during the summer. The whale is now off the coast of Vancouver Island and appears robust and to be behaving normally.
But experts became concerned when a contractor for National Oceanic and Atmospheric Administration Fisheries on March 16 photographed the whale in Barkley Sound, B.C., and reported a lesion around the tagging site and two lesions on the opposite side of the animal.
The whale also has been coughing up mucus, and so the decision was made to dart the whale with antibiotics on March 31 and April 1, to stave off any kind of systemic infection, said Martin Haulena, veterinarian for the Vancouver Aquarium, a member of the response team.
Experts on a media call coordinated by NOAA on Tuesday said the animal will continue to be monitored.
Tagging provides essential information for biologists seeking to understand the movements and population dynamics of animals and, in this case, to also understand where those movements overlap with people, such as shipping lanes.
The satellite tag used on the whale is about 11 inches long and weighs about 14 ounces, said Alex Zerbini, a tagging expert at the University of Washington/Cooperative Institute for Climate and Ocean Studies and a NOAA Fisheries affiliate. The tag is carried in the body of the whale, transmitting data, until the whale naturally sloughs it off, much as we would a splinter. The process takes anywhere from several months to years.
The consensus of a panel of experts examining photos of the lesions around the tag site was that the lesions are within the range of reaction that would be expected as the body extrudes the tag. However, it was unusual compared with other records of similarly tagged whales.
In addition to administering antibiotics, scientists took breath-droplet samples for analysis. It could take weeks for those cultures to grow out.
The tags are used in whales worldwide with one exception: endangered southern resident killer whales, after the death of orca L95 in 2016, several weeks after the orca was tagged.
A necropsy of the orca found pieces of the tag broken off deep within the animal’s flesh and a fungal infection, said Stephen Raverty, another member of the gray whale response team, and veterinary pathologist for the Animal Health Center at the British Columbia Ministry of Agriculture and University of British Columbia.
The pathogen likely was introduced by the tag, which had not been sterilized properly, an expert review panel found.
There was no breach of protocol in the tagging of the gray whale. The hope is that once the animal extrudes the tag on its own, the lesions will heal normally.
The purpose of the tagging study is to learn more about a small group of about 250 gray whales that comprise the Pacific Coast Feeding Group. Unlike most gray whales, they do not make the long migration along the West Coast of North America from wintering and calving areas off the coast of Baja California, Mexico to summer feeding grounds in the northern Bering and Chukchi seas.
The gray whale is not a protected species. After being hunted nearly to extinction, today the population of gray whales in the northeastern Pacific is considered strong at about 20,000 whales. The mighty grays, measuring about 39 feet long and weighing about 60,000 pounds, were taken off the U.S. Endangered Species Act list of protected species in 1994.