A pregnant humpback whale was found dead floating in the northern waters of Chichagof Island in late July.
A vessel in the area reported the carcass to the National Marine Fisheries Service and Glacier Bay National Park. The sighting happened on July 22, off the coast of Point Adolphus – an area known for its whale and bird watching.
Mandy Keogh is the Alaska Regional Stranding Coordinator with NOAA Fisheries. This whale is considered stranded by NOAA and Keogh said Glacier Bay National Park is the stranding organization in that area.
“They were on the water already doing their humpback whale research. Their researchers were able to go out and find the carcass and then they secured it to land with some rope..” Keogh said they feared it would float away.
Keogh said sometimes the agency doesn’t hear about dead whales and when they do sometimes the carcass is gone by the time stranding teams respond.
“And we never see it again. We’re not able to gain any information about that animal,” she said. “So it was great they were able to secure it.”
“We do know it was a 23-year-old female, she was first observed in 2001, as a calf. And she was pregnant.” Keogh said.
Keogh and her team ran into logistical problems trying to get to Point Adolphus from Juneau but managed to arrive two days later on July 25. The reason for the urgency was so that they could conduct a necropsy – an animal autopsy.
“When we’re doing a necropsy we’re gaining information from this animal, just basic morphometrics, body condition, sex of the animal. When Glacier Bay secured the whale to shore, they were able to capture some photos of the flukes and the dorsal, like from the tail of the animal. They were able to identify that whale, so it was a known individual.”
The necropsy took several hours.
The humpback whale was pretty bloated, Keogh said, and it was in an advanced decomposition stage. “So that limits some of the things we can learn like some of the viruses. If we were looking for viruses or things like that, sometimes they don’t survive degradation.”
Keogh said scientists look at blubber for lipid content and body conditions. They also look for any signs of parasites and diseases.
“So the same thing they would do on a human when they’re doing a post-mortem examination,” Keogh said. “And so you have to fix those slides and stain them, and then go through and process them. So that takes a couple of weeks at least, to go through that.”
When a whale, like this one, is already decomposing it can make it more difficult to figure out how it died.
“Sometimes the decomposition on a cellular level is just too far along that we can’t fully assess whether there was a disease or something going on,” she said.
Still, Keogh said the pregnant whale was in really good body condition.
“So we collected a bunch of samples to assess how much lipid she had in her blubber. And we took a lot of measurements of her blubber throughout her entire body to try and get a better handle on what happened,” she said. “She wasn’t skinny, she was in good condition.”
The team of scientists also collected whale feces to try and figure out what she was exposed to.
“If they are eating prey that has been eating on the plankton or things that make harmful algal blooms, it’ll work their way to the systems,” she said.
Keogh also said they collected baleen for research. The results of the tests will take several weeks.
Despite the carcass’s state, the team of scientists learned a lot – the humpback was 48.6 feet long. Keogh said she will compare the data they’ve gathered with other whales and also save samples for other researchers.
“There are some researchers that can go back and you can measure hormones and look at past reproduction, or the stress levels,” she said. ”
This information will provide information about the humpback whale population but also this specific whale.
“And that would be interesting, since we ‘ve never seen her with a calf,” Keogh said.“And she was pregnant, so it would be interesting to see if there’s any other indication she was pregnant previously. And that’s something we can measure in baleen, which is a place that hangs down from their mouth where they feed.”
The necropsy team found evidence suggesting blunt force trauma from a possible vessel strike, but Keogh said they will need to wait on some of the veterinary tests to determine the cause of death.
But, they found other interesting things while doing the necropsy – including a murrelet inside the whale’s stomach.
“We think this happens when they’re feeding. They seem to go where birds are at the surface, there’s usually fish underneath. So as they’re going up to feed on the fish, they incidentally capture birds,” she explained.
Because this area gets a lot of traffic from people actively trying to observe whales, Keogh said it’s important that they also know to report anything unusual they see. That could be someone violating the rules between humpback whales and human interaction. Or, seeing an animal in distress, being harassed or even dead.
Keogh said if possible, take pictures, get a general location or the latitude and longitude, and any other details.
“We can try and get a team out to respond to better understand to learn about these animals, both the whales but even seals, sea lions and dolphins and porpoises; we track all dead, stranded or entangled animal animals throughout Alaska,” she said.