Hakai Magazine

Stephen Raverty next to dead juvenile humpback whale
Prior to conducting a necropsy, veterinary pathologist Stephen Raverty from the BC Ministry of Agriculture inspects a juvenile humpback whale, washed up on a Calvert Island, British Columbia, beach. Photo by Larry Pynn

A Humpback Whodunit

A necropsy carried out on a remote British Columbia beach seeks to answer how a young humpback died.

Authored by

by Larry Pynn

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The whale on the beach has a story to tell and Stephen Raverty is here to extract it.

The veterinary pathologist has traveled to British Columbia’s remote central coast on this sunny May Sunday to perform a necropsy on a male humpback that washed ashore on the surf-tossed west side of Calvert Island.

Raverty is a towering man, dwarfed only by the whale itself. He struggled to get here, navigating up and down shoreline trails mined with exposed tree roots, but refusing to relinquish his black plastic case filled with necropsy instruments and sampling gear. He concedes that getting to the marine mammals he necropsies along rugged coastlines can be the least favorite part of his job.

Raverty works for the BC Ministry of Agriculture in a comparatively sterile animal-health center in Abbotsford, an hour east of Vancouver. Relatively mundane work on domestic animals, including the search for poultry and cattle diseases, pays his bills.

His real passion is marine life and has been ever since he served as a volunteer at the Vancouver Aquarium at age 12, peering over the shoulders of veterinary staff as they investigated diseases in a host of fish, frogs, reptiles, and the odd harbor seal.

Nobody takes pleasure in this humpback’s death. But whales die for all manner of reasons, and when they do, Raverty can only hope they wash ashore on an accessible beach. This particular carcass was spotted two days ago—bloated, belly up, and malodorous—less than an hour’s hike from the Hakai Institute’s Calvert Island Ecological Observatory,* located just over 90 minutes by seaplane northwest of Vancouver. Staff from the institute alerted Fisheries and Oceans Canada (DFO) about the whale and Paul Cottrell, the agency’s marine mammal coordinator, contacted Raverty, and got the operation in motion with logistical support from the Hakai Institute. The necropsy team is rounded out by Taylor Lehnhart, a technician from DFO.

Map of Calvert Island on the British Columbia central coast.

Map data by OpenStreetMap via ArcGIS

Raverty wipes sweat from his face, takes a tug of water, and sharpens a fillet-style, 25-centimeter forensic knife—the same type used on human cadavers. He puts on gumboots and waterproof bib overalls, which are incinerated after about every third necropsy. “They just get a little too aromatic.”

Raverty conducts a methodical walk around the carcass to assess the breadth of the task ahead and to look for obvious clues to cause of death. I poke the carcass with my finger and it bounces back, like the hull of a rubberized, inflatable craft.

This whale fetched up on its back during its northerly spring migration, eyes pressed against the sand, and furrowed belly with 25 ventral grooves pointing skyward. These grooves stretch like an accordion during feeding, allowing the whale to open its jaw to take in vast amounts of seawater. The baleen inside the mouth then acts like a filter to capture prey, typically schools of small fish and krill.

Raverty’s eyes follow the symmetry of the carcass, looking for abnormalities in alignment of the bones or unusual coloring that might suggest a lack of nutrition or injury. Dilation of the throat in this case hints at more findings to come.

Since the team can’t flip the hulking whale over, the back of the animal, including the top side of its spinal column, is largely inaccessible during the necropsy. Rising tides, the challenging access, and a small necropsy team also hinder a fuller skeletal examination.

The whale is pockmarked with beak bites from scavenging bald eagles—now relegated to the shoreline trees, their squeaky-door calls imploring Raverty to get on with it.

The whale’s tongue is a gooey grayish blob protruding from the mouth. Raverty looks inside for foreign debris such as plastics or fishing gear, or evidence of damage to the baleen, but finds none. Black skin peels from the tail flukes, which are tied to a tree with close to 50 meters of rope to prevent the tides from returning the carcass to the dark abyss.

Raverty leans over for a closer inspection of the pectoral fins on the sides of the whale—white on the bottom, dark on top, and mottled with freeloading barnacles. He observes scar lines near the base of each fin, suggesting the whale may have encountered fishing gear at some point in its life. “Those are the types of things we’re looking for, evidence of human interaction,” he explains.

There’s more than idle curiosity at stake today. The necropsy results will form part of a baseline of information on the overall health of the humpback population—estimated at 20,000 or more in the North Pacific—and could potentially point to problems such as entanglement with fishing gear or ship strikes that humans are in a position to tackle.

Raverty emphasizes that the necropsy is just one part of the investigation. He relies upon a host of other experts—lab technicians to analyze tissue samples, biologists, ecologists, oceanographers, and climate-change specialists—whose findings will later contribute to a broader understanding of why marine mammals die. Half the time, necropsies do not determine cause of death. “Each is a unique challenge, a learning process,” he explains. “It provides a glimpse into the natural history of these animals.”

Despite his international reputation for necropsies on marine life, Raverty remains surprisingly modest—soft spoken and polite, too. He has performed some 2,200 necropsies of marine mammals from across North America over the past two decades—not just of humpbacks, but killer, gray, fin and beluga whales, as well as seals and sea lions, porpoises, dolphins, and sea otters. About 20 percent of the necropsies are conducted in the field—generally on the whales, which are too big for transport—and the remainder are done in his lab under more controlled conditions with better equipment and technical support.

DFO technically owns the carcass and issues permits to allow Raverty to take tissue samples for research purposes and to better inform federal management of marine mammals. It is not unusual for him to work for free on his own time, such is his devotion to the job. “I basically hold his tools,” jokes Cottrell, who is Raverty’s right-hand man during such procedures. He also takes notes of the veterinary pathologist’s verbal findings as the necropsy unfolds.

Cottrell and Lehnhart, wearing disposable white Tyvek protective coveralls sealed with duct tape at the ankles, also help by taking measurements of today’s whale. The length is 7.82 meters, suggesting a juvenile about two years old.

With the preliminary inspection over, it’s time to start slicing.

Raverty and Lehnhart use their knives to carve off heavy rectangular chunks of blubber and skeletal muscle to access the internal organs. Cottrell wields a flensing knife close to two meters long befitting a gladiator in Rome’s ancient Colosseum.

Thick blubber suggests the young humpback had been getting plenty of food. In contrast, at least 208 gray whales—many of them emaciated—have washed ashore this year on the west coast of North America, from Mexico to Alaska. The poor condition could be a sign that the estimated population of 27,000 gray whales is at carrying capacity in the eastern North Pacific or that 2018 conditions in the Bering Strait provided insufficient food for the whales prior to their southerly migration.

This humpback carcass has been rotting away for perhaps a week, including the time before it washed ashore. With the exterior blubber removed, Raverty plunges his knife deep into the whale’s side, releasing a putrid stream of dissolved blubber. “With the heat, it just liquefies,” he explains.

Paul Cottrelland Taylor Lehnhart to cut away the blubber from a dead humpback whale

Paul Cottrell, foreground, and Taylor Lehnhart from Fisheries and Oceans Canada use flensing knives to cut away the blubber and skeletal muscle from the whale’s torso. Photo by Josh Silberg

The smell is uniquely repulsive, certain to linger for hours in our nasal passages. Keith Jordan, a maintenance worker integral to the Hakai Institute’s operations on the island, watches the necropsy unfold from a distance and recoils with disgust. “That’s unreal,” he says, hand over his face. Raverty has toughened up over the years. “I can’t smell it anymore,” he says. “I’ve gotten used to it, I guess.”

Noxious gases emitted from a bloated whale carcass can almost make a person pass out. The internal pressure is also extreme, putting the necropsy team in the spray zone. For Raverty, it all comes with the territory. “I’ve seen him get it a few times, but he keeps coming back for more,” Cottrell remarks with a smile.

Raverty pushes the knife ever deeper and his black gloves become lost in the gooey entrails. The mystery of this humpback only deepens, too. The gonads and the internal organs, including the liver, heart, intestines, and kidney, have shifted from the abdominal cavity to the throat and chest. There are two potential explanations for the rearrangement: blunt-force trauma, or the extreme buildup of internal pressure after death. Over the years, Raverty has observed the bizarre effects of internal gas buildup, including stomachs of bloated whales extruding from the mouth, or the rectum from the anus.

As the hacking and tearing continues, Raverty proceeds past the ribs to expose the heart and lungs, which resemble a big slab of corned beef. One rib protrudes from the body like a piece of driftwood, next to coils of large intestines as thick as Raverty’s forearms and measuring perhaps 10 meters in length.

He announces he’s found part of the penis and the corpus cavernosum, which contains most of the blood during an erection. He sees the urinary bladder, too, but it’s empty, lacking the urine he typically samples to screen for indication of muscle injury, harmful algal toxins, and faulty kidney function.

At 2:20 p.m., it’s lunchtime—and, yes, sushi is off the menu. We dine on sprout sandwiches, cookies, and apples. “I’ve tried bowhead whale meat,” Lehnhart offers up as small talk. “It’s not very good.”

Calvert Island, British Columbia

Calvert Island, British Columbia. The juvenile humpback whale washed up on the beach in the lower right. Photo by Keith Holmes

The hard physical work over, Cottrell and Lehnhart discard their stained coveralls for new ones as the necropsy shifts gears. “Round two, I’m ready,” Cottrell says. The team collects several tissue samples, ranging from two to 10 centimeters in thickness, and places them into sterile plastic bags, chilled with ice packs, to be lab tested for bacteria, fungi, viruses, and harmful algal toxins such as domoic acid and saxitoxin.

Domoic acid can be poisonous to marine mammals such as California sea lions that eat small fish, including herring, anchovies, and sardines that feed on the toxic algae. The toxin can make its way into the sea lion’s bloodstream and its brain, causing seizures, heart disease, and even death.

How these same toxins affect a creature as large as a whale remains unknown. One theory is that infected whales are at greater risk of ship strikes. The toxins may “target the brain and cause disorientation,” Raverty explains.

They take a baleen sample to screen for feeding and hormone levels related to stress and reproduction. Cottrell pries off samples of a humpback-specific barnacle—a walnut-sized crustacean that spends its adult life embedded in the skin of whales, using its feathery leg-like cirri to grab a fast-food diet of tiny plankton as its host swims through the ocean.

Stephen Raverty prepares to inspect a whale’s internal organs

Stephen Raverty prepares to inspect the whale’s internal organs. Photo by Larry Pynn

“They’re taking a ride to the buffet,” Larry Taylor, a doctoral student at the University of California, Berkeley, tells me later in a phone interview. “These whales are traveling to rich, productive waters to feed, and the barnacles get to enjoy the feast.” Barnacles cause no apparent harm to the whales, but can yield important information. Shell growth layers contain chemical signatures related to temperature and chemistry of the ocean waters visited by the whales, hinting at their migration routes.

The necropsy concludes after two hours, hurried by an incoming tide gnawing away at the gently sloping sands. The size of the whale and the inability of the team to access all body parts contribute to the speed of the job.

Everyone heads back to the Hakai Institute’s facilities, knowing it will be months before all the samples have been analyzed and more light has been shed on the cause of the whale’s demise. Raverty takes one last look at the hacked-up carcass and offers an educated guess as to the cause of death: “I wouldn’t be surprised if it’s a fracture.”

Indeed, two days later a four-person team led by Michael deRoos from Cetacea, a British Columbia company that specializes in creating skeleton exhibits, arrives to take up where the necropsy team left off. While separating the whale’s bones from the rest of its flesh, deRoos discovers extensive bruising of the flesh on one side of the skull, and loose pieces of bones suggesting a possible fracture on the other. One plausible scenario is a ship strike near Hakai Pass, about five kilometers from where the whale washed up.

What we do know is that the food web benefitted. “There were quite a few wolf tracks around the whale,” deRoos says. “They’d been tearing into the tongue, a good chunk of it chewed off. It’s a pretty big windfall for any scavengers out there. I imagined the wolves curled up with full bellies, somewhere in the bushes, watching us gut the thing up.”

A time-lapse video of the necropsy. Video by Josh Silberg

The bones are put into slings and flown by helicopter to the Hakai Institute’s property and sunk into the seawater by the dock to let nature continue the defleshing process. In two or three months, deRoos explains, the bones will be taken to Cetacea for further treatment, including degreasing using a process akin to dry-cleaning. The giant machine sucks the oil from the bones, says deRoos. Crews will reassemble the skeleton in segments before barging it in crates back to Calvert Island next summer to be put together and suspended as a full skeleton from the ceiling in the Hakai Institute’s communal dining room.

DeRoos’s earlier work—the skeleton of an old male sea otter that washed ashore on Calvert Island in 2016—already hangs in the lodge, meticulously reconstructed so that it appears to be diving for a sea urchin. Eric Peterson, who cofounded the Hakai Institute with Christina Munck, his wife, expects deRoos to give the whale skeleton a similar treatment. “It’s a celebration of one of nature’s great creatures and a celebration of the skill and ingenuity of an artist doing incredible work in an interesting medium,” Peterson explains.

In the meantime, labs across North America will continue to extract information from all those samples collected by Raverty and his necropsy team. A US National Oceanic and Atmospheric Administration office located in Seattle, Washington, gets some material, with additional samples headed to other state and university veterinary labs with particular expertise or interest in marine mammal health in California, Illinois, and Georgia. The barnacles end up at the California Academy of Sciences, as part of graduate students’ research projects, while the National Institutes of Health in Maryland looks for unusual disease agents such as the cat parasite Toxoplasma gondii, flushed into the oceans through toilets.

Some tissue and blood samples will also be frozen and available to scientists launching new studies years or even decades from now. “It’s quite amazing, all the different pieces that folks want for research,” Cottrell says. “It seems to go on forever.”

Clearly, this young whale’s story did not end when it died.

Its flesh fed a full range of terrestrial and marine scavengers. Its fate becomes part of the known record of whale deaths along North America’s west coast, helping to inform ocean managers and enhance a greater database of long-term trends, be they related to disease, human actions, or ocean conditions. And its skeleton is likely to educate and enthrall visitors to Calvert Island for decades to come.

*The Hakai Institute and Hakai Magazine are both part of the Tula Foundation. The magazine is editorially independent of the institute and foundation.

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Cite this Article:

Cite this Article: Larry Pynn “A Humpback Whodunit,” Hakai Magazine, Sep 24, 2019, accessed June 21st, 2024, https://hakaimagazine.com/features/a-humpback-whodunit/.

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