Beached whales appeared to be fighting infection
Researchers looking into cause behind sickness, strandings
The two pygmy killer whales that stranded themselves at Sugar Beach on Sept. 24 had inflamed lymph nodes that suggested they were fighting infection, just like the pygmy killer whales that stranded themselves at the same beach on Aug. 29, according to a postmortem exam.
“We have no reason to believe that there’s some kind of environmental toxin or something going on at Sugar Beach that is harming the whales, just to be real clear about that,” said Jeff Walters, chief of the National Oceanic and Atmospheric Administration’s Wildlife Management and Conservation Branch. “Whatever was going on with them, it’s going on somewhere else. It’s just they ended up at Sugar Beach.”
On Tuesday, Walters and other officials shared early results from the necropsies of the two whales, who were euthanized after visual and blood tests showed little chance for survival at sea.
Kristi West, associate researcher at the University of Hawaii Stranding Lab on Oahu, said the two whales were both adult males. One was in “poor body condition” and 33 pounds lighter despite being slightly longer than the other whale.
West said researchers also found unusual food items in the esophagus and stomach of both animals, including a Moorish idol in one whale’s esophagus and “a fair amount of plant material,” including leaves and marine algae. This indicated the animals weren’t feeding normally prior to the stranding.
A typical pygmy killer whale stomach would contain squid beaks and deep-water fish, but “this is not what we saw,” West said.
She explained that the whales also had abnormal and inflamed lymph nodes, similar to the stranded whales in August, which “does suggest the animals were likely fighting some type of infection at the time of the stranding.”
Future disease screening and tests of the whales’ tissue and genetics could help researchers identify the infection and what caused it. The animals’ inner ears could also reveal whether they experienced acoustic trauma before the stranding, but the ear bones first have to decalcify, and some of the work needs to be done in France, which could take at least six months to a year, West said. The lab is also awaiting results from the whales’ lungs.
David Schofield, NOAA regional standing coordinator, said the two whales were part of a pod of six that were being monitored due to unusual nearshore behavior since Sept. 13. The animals were observed “logging,” in which they rested parallel to the surface, and “bottling,” in which they bobbed up and down in a near-vertical position, like a partially filled Coke bottle. These behaviors indicated the animals were lethargic and low on energy.
Schofield said NOAA tried to coax the animals farther out to sea, but the whales only continued to move parallel to shore. So, staff and volunteers just continued to monitor them.
At 5:55 a.m. Sept. 24, the NOAA hotline received reports of the stranded whales at Sugar Beach. Schofield said NOAA planned to put tags on the animals and release them back into the wild if they were healthy. But blood tests of the animals revealed “critically low” alkaline phosphatase enzyme levels, and both whales had signs of emaciation, abnormal heart rates and labored breathing. The whales were euthanized and flown to Oahu for analysis.
While researchers still aren’t sure what infections the whales suffered from, Schofield said that some diseases that have been found in Hawaiian whales and dolphins include morbillivirus, which was found in a stranded Fraser’s dolphin off Maui in 2018, and toxoplasmosis, a parasite found in the feces of feral cats that also has been documented in spinner dolphins and seals.
NOAA officials said they didn’t think the unusual contents of the whales’ stomachs is what caused them to be sick. It was more likely that because they were close to shore, they ended up eating whatever they could find.
As for the other four whales, they were seen for another week in Maalaea Bay. But over time their energy level seemed to improve, and they started traveling longer distances and moving more naturally, Schofield said.
The pod of four eventually became three and hasn’t been seen since Saturday. Schofield was hopeful they’d gone back out to sea. Pygmy killer whales normally live in waters over 985 feet deep.
Schofield said the situation was similar to a stranding in 2009, when six pygmy whales were spotted in Maalaea Bay, but only one stranded while the rest eventually disappeared. He said it seems the animals were caring for the sicker member of the pod.
“We think we may have had some of that in this case – the sicker ones stranded and the healthier ones, after a few days of getting their bearings back around them, went back out to sea,” he said.
The whales that stranded on Sept. 24 were from a different pod than the ones that stranded at the same beach on Aug. 29. Six of the 10 pygmy killer whales that beached themselves that morning were coaxed back into deeper waters, while four were euthanized. A dead calf was found later that day about a mile north of the stranding spot.
Necropsies of the animals indicated they suffered lung abnormalities and had abnormal lymph nodes, suggesting that they may have been fighting infections. The calf, likely 3 to 6 months old, was confirmed to have had pneumonia.
When asked whether the two strandings were anomalies or indicative of a bigger problem within the population, Schofield said that “we don’t have answers yet” but that future tests will help shed some light.
He explained that Maalaea is a “broad open bay with a very shallow shelf” that’s comparable to other places that have seen mass strandings, such as Tasmania, Australia and Cape Cod Bay in Massachusetts. These areas can be disruptive to the animals’ echolocation, especially if they’re already weak.
“They’re used to diving in deep water,” Schofield said. “If they’re presented with this vast, long shelf of shallow water, it can be confusing to them.”
Scientists think whales and dolphins may strand themselves after growing weak, and being forced to live off the nutrition and moisture in their own blubber. As the blubber becomes thinner, they have to work harder to stay afloat.
“Animal stranding is an effort to support the blowhole above water so it can breathe,” Schofield said. “That’s why in most cases when the public is pushing the animal off the beach and back into the water, they’re either going to go somewhere and die very quickly, or they’re going to restrand, because they want to come ashore.
“Sugar Beach is a gentle, sloping beach and maybe is a comfortable beach for them.”
Members of the public who see a stranding or unusual nearshore behavior should call NOAA’s hotline at (888) 256-9840.
* Colleen Uechi can be reached at email@example.com.