by Todd McLeish
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ONE OF THE OFFICIAL participants in the annual Washington sea otter surveys was Jessie Hale, a graduate student at the University of Washington, where she studies sea otters under the guidance of professor Kristin Laidre. Hale invited me to join her research team for a couple days to learn how the diet of sea otters in the region has changed in the forty years since the animals were first translocated to the state. I met her and undergraduate research technician Abby Van Hemmen at the Ozette Lake campground in Olympic National Park, and we drove for twenty minutes along restricted-access logging roads through patches of old-growth spruce and fir forest and small, recent clear-cuts highlighted by generous stalks of foxglove. At the end of the road, three cabins and a trailer were hidden in the trees at the edge of a cliff known as Duk Point, one of five sites Hale uses to observe sea otter foraging behavior. A tiny observation point was carved from the salal shrubs at the edge of the cliff, a spot just large enough for the three of us to stand. From our vantage point, we could see a group of a dozen exposed boulders lying three hundred yards offshore, most no larger than a Volkswagen Beetle. A couple miles to the south we could see Bodelteh Islands, sea stacks considered the westernmost point of land in the Lower 48.
Hale quickly scanned the nearby waters with her high-powered telescope and counted twelve sea otters within easy view, and she immediately homed in on the one individual located closest to shore. Without a word of explanation, she began to call out data. Van Hemmen had already pulled out a stopwatch and clipboard filled with prepared data sheets, and she started writing. It was 4:14 p.m. when Van Hemmen started the stopwatch at the moment Hale called out “down” to indicate the otter had started its foraging dive. Thirty-three seconds later, when Hale called “up,” Van Hemmen clicked the stopwatch again and made some notes on her clipboard. Wearing a black eye patch to combat eye strain during long hours of staring through her telescope, Hale mumbled to herself as she tried to identify the variety of prey with which the animal returned to the surface. “Well, whatever it is,” she finally said, “it’s really enjoying it.” Although identifying prey is the focus of Hale’s research, it isn’t easy. It is not uncommon for her to be unsure of what is being eaten. Frankly, I was amazed that she could ever identify from two hundred yards whether it was a snail or crab or clam, let alone the particular species involved. I tried repeatedly and failed every time. All I could see was a tiny blur being quickly manipulated in the otter’s paws. I seldom could even tell what color the prey was, let alone its shape or size, before the animal finished eating it and submerged again.
“Down,” Hale called out once more, and less than a minute later, “up.” She tries to observe twenty-five consecutive foraging dives from one otter before moving on to the next animal. Any more than that and she says it may skew her results. But she often struggles to reach twenty-five. The otters sometimes move out of view or stop foraging entirely and begin to groom, or a male may arrive and attempt to mate with the target female. And other otters will sometimes join the foraging activity, which often results in Hale’s losing track of which animal she is focused on as they repeatedly dive and surface together.
At 4:49, she moved on to another otter, one that was located farther north and out of the sun. She provided a running narration for the next twelve minutes of everything the otter did, from diving and surfacing to smacking the prey on its chest and rolling around in the water. At 5:02, a young male otter cruised in close to shore, grooming, vocalizing, and looking around, followed minutes later by a female, which turned out to be its mother. Hale focused her telescope on the pair and had a much easier time identifying prey items. The first one was a crab, which the mother shared with her pup. On her next dive, the female otter surfaced with another crab, which she ate almost entirely herself, sharing only one leg with the pup. After momentarily swimming out of sight, she surfaced with a large ochre sea star, which she bit twice and dropped. “She definitely didn’t like the taste of that,” Hale said with a smirk. Two dives later the otter surfaced with several small items, probably snails, then did so again. But after eight dives, both otters disappeared behind some trees. And given the continuously poor lighting conditions and the distance that most otters were from our observation point—not to mention our own hunger—Hale announced we were calling it a day.
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IN THE 1990s, biologists established twenty-nine sea otter observation points along the Olympic Peninsula from which to study and monitor otters that were tagged during earlier research projects. Some of those sites were also used to collect data about sea otter foraging from 1993 to 1999 and again in 2011 and 2012. So Hale used those same sites for her foraging studies, enabling her to compare how otter prey in those locations may have changed through the years. She began her study in 2014 and planned to continue making monthly observations at her five sites until at least 2017.
Scientists speculate that the otters are probably consuming smaller prey than they did in the 1990s because the larger prey have already been eaten by earlier generations of sea otters. “The assumption is that when sea otters move into an area, it’s kind of pristine and it’s got this really huge invertebrate population with gigantic urchins. And then the otters come in and eat their favorite food first, which in Washington is usually urchins,” Hale explained. “Then they work their way down the food web, kind of like a buffet, starting with their favorite things and moving to their second-favorite things. The assumption is that by now they’ve eaten all of their favorite foods and are now eating smaller stuff.”
Hale has already found that hypothesis to be somewhat true. Based on her preliminary data, the otters are eating a great many more snails than they did in the 1990s, while consuming fewer urchins and clams. The majority of their diet in the ’90s was clams, but clams became the second most common prey a decade later. At the southern end of their Washington range, near the resort area of Kalaloch, where otters have only recently been observed and where they have not yet consumed all of their preferred prey, Hale observed the animals eating Dungeness crabs and razor clams.
After we discussed Hale’s sea otter research at our campsite late into the night, I was awakened in my tent the next morning by the loud croaking of a pair of ravens. When I went looking for them at a walkway over an outlet stream of Ozette Lake, I found five river otters careening about in the water—a mother and pup on one side of the bridge and three more pups romping about together on the other side. The ravens were perched on a downed log by the river’s edge right next to the group of three pups, and the birds’ noisy vocalizations suggested to me that they were hoping the otters were going to catch some fish that the ravens would confiscate for their breakfast.
River otters are the only other species of otter in North America, and they are quite easy to distinguish from sea otters. River otters are primarily found in freshwater, though they are occasionally found in quiet saltwater bays, and they are less than half the size of sea otters. They also spend half of their time out of the water, have small paws that enable them to be adept at running on land, and they swim on their bellies, all of which are vastly different from sea otter behaviors. In addition, river otters give birth to as many as four pups at once, compared to the single pup of a sea otter, and river otters are almost always found alone or in small family groups, never in large rafts. And while on first glance the two species may appear similar, I find that sea otters tend to have a shaggy look compared to the well-coiffed, sleek river otters.
Among the thirteen species of otter on earth, just one other species besides the sea otter—the rare and little-known marine otter of coastal Chile, Peru, and extreme southern Argentina—confines itself to salt water rather than fresh. But it tops out at just twelve pounds and spends most of its time on land, so it is unlikely to be mistaken for a sea otter.
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HALE AND VAN HEMMEN were awake when I returned to our campsite after watching the river otters, and we soon departed for Duk
Point again. When we arrived, the lighting was good and several otters were foraging somewhat close by. Hale homed in on one animal whose first dive resulted in a crab—Dungeness or kelp crab, most likely, though several other varieties were possible, too. The female otter brought up a mass of seaweed encased with snails in its next three dives before a male arrived and attempted to mate. “Ooh, ow, that hurts,” Hale cried out anxiously as she watched. “He’s really biting her. Yikes!” And as fast as the mating attempt started, it was over. The male moved on, and the female returned to foraging. It brought up more seaweed, then two or three snails at a time, and once I even noticed it removing a snail from the pouch in its armpit. During a thirty-eight-minute period, the otter made the requisite twenty-five foraging dives, the first time Hale had recorded the target number of dives since I arrived.
As we waited for another sea otter to begin foraging, Hale pointed out several animals exhibiting what she considered typical—and entertaining—behaviors. She called one “touchdown hands,” when the otter raised both paws vertically in the air, probably to keep them warm and dry, which made it look like the animal was a referee signaling a touchdown. Another behavior she called “Hula-Hooping” involved an otter raising all four appendages in the air while simultaneously rolling in the water. And just prior to departing Duk Point for the morning, Hale laughed as she observed an otter rub its belly with one paw and pat its head with the other, a skill I never successfully accomplished as a child and one that I decided not to attempt while Hale and Van Hemmen were watching. “They often do two different behaviors with their hands at the same time,” she said, “but more often they scratch their head with one paw and scratch their armpit with the other.” I couldn’t help but laugh at the image that brought to mind.
The next otter Hale studied repeatedly brought to the surface much larger prey than did the previous otters we had observed, though she also came up empty handed more often. On her first dive she captured a gumboot chiton, a massive gastropod that Hale first thought was a sea cucumber. Van Hemmen noted on her data sheet that the chiton was “a three-plus,” meaning it was more than three times the size of the sea otter’s paw. The otter quickly ate half of it before diving again. That time she captured nothing. The next time she surfaced with a large red sea urchin, another prey item judged to be a three-plus. After another unsuccessful dive, she retrieved a slightly smaller red urchin followed by a midsize purple urchin, nothing, three mussels, and another red urchin.
As we departed Duk Point, I asked Hale why the last two otters we observed had captured such different prey items even though they were foraging quite close to each other. Why didn’t the first otter find the same large prey that the second one found? Were they simply specialists in different kinds of prey? I would have guessed that both would have captured whatever opportunistic prey items they stumbled upon and would have had an equal likelihood of finding a large urchin or chiton. With a quick glance at the data sheet, Hale came up with a plausible answer. She said the first otter made very short dives but succeeded in capturing something every time. It probably settled for lesser-quality prey so it could return to the surface more quickly. The second otter stayed below the surface for longer periods than the first animal and was unsuccessful at capturing any prey almost half the time. But when it captured something, it was usually pretty big. Was there a physical reason that restricted the first animal to shorter dives? Hale didn’t think so. She guessed that they were simply two different foraging strategies, perhaps learned from previous generations. “Someone should attempt a cost-benefit analysis of the two foraging strategies,” said Hale. “But it’s not going to be me.”
Chapter 12: Walter
VANCOUVER ISLAND, BRITISH COLUMBIA
THE CALL FROM Tofino, British Columbia, came in to the Marine Mammal Rescue Center at the Vancouver Aquarium just after dinnertime on October 17, 2013. Someone had reported to the local police that a sea otter in the harbor had an injured flipper and was unusually lethargic. The animal had been hanging around in an area of shallow, stagnant water, and contrary to typical otter behavior, it was allowing people to approach it without fleeing. That was a clear sign to the rescue center staff that the animal was in trouble. By nine o’clock that evening, photographs and videos of the otter had been shared with biologists from Fisheries and Oceans Canada, rescue center manager Lindsay Akhurst, and aquarium veterinarian Martin Haulena, all of whom agreed that the animal needed to be retrieved.
Sea otters aren’t the typical animal that the aquarium rescues. Since the program was established in the 1960s, it has responded to about 150 calls each year to collect and rehabilitate marine mammals, but the overwhelming majority are young harbor seals that have become separated from their mothers in the first weeks or months of their lives. There are numerous reasons why harbor seal pups may need to be rescued, from first-time moms not knowing how to care for them to injuries caused by human activities. And the rescue center has a permit from the Canadian government to respond to such calls whenever necessary. The center also regularly responds to stranded or injured harbor porpoises, elephant seals, and sea lions, and in recent years it has even begun to go into the field to disentangle marine mammals, mostly sea lions, that have become caught up in fishing gear. But it had responded to only one sea otter call before the Tofino animal, and that was a year before in Washington State. That animal was found to have massive liver failure, and it died soon after it was collected.
“We’re basically a facility that responds to a public need,” explained Haulena. “We don’t go out looking for animals, but we always respond when someone calls us to do something.”
So the next day the rescue center dispatched two teams of personnel to collect the animal. One team had planned to fly the 180 miles to the coastal resort community, but the plane was fogged in and never left the airport. The second team, which included Akhurst, went by car and ferry, a nearly six-hour trip. It was sunset by the time they got there, but an officer from Fisheries and Oceans was standing by at the rocky shoreline keeping an eye on the male otter they later named Walter. He didn’t look good. Walter was hardly noticeable, hidden between two docks and amid piles of seaweed, sticks, and detritus. Since no healthy sea otter would submit to being in those conditions, the rescue center team was even more determined in their assignment.
Given his poor health, Walter was easy to capture. Wearing a headlamp in the near darkness, the Fisheries and Oceans officer distracted the otter from one side while Akhurst snuck in from behind with a large hoop net and scooped him up. Although the animal initially tried to swim away, he was far too weak to escape and was easily placed in a portable kennel for the trip back to Vancouver. Because sea otters can easily overheat when out of the water, Akhurst stopped several times during the return trip to purchase a total of twenty-five bags of ice to put inside the kennel to keep Walter cool.
Arriving back at the rescue center at two in the morning, Walter was guided into an enclosure and pool and provided with what may have been his first healthy meal in days. During the next forty-eight hours he received round-the-clock care, including intravenous fluids, pain medication, and antibiotics to stabilize him. The full extent of his wounds was still mostly unknown.
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THE VANCOUVER AQUARIUM’S marine mammal rescue center sits behind a green fence on the city’s waterfront and consists of an office trailer, several sheds where examinations and surgeries take place, and a number of outdoor pools of various sizes for holding and rehabilitating marine mammals. Two days after the otter’s rescue, veterinarian Haulena and his technicians anesthetized Walter and conducted a thorough examination. He was in worse shape than they imagined. Walter was severely malnourished; he had a badly fractured flipper, numerous shattered teeth, and tenderness in his shoulder; and both eyes had been perforated, rendering him blind. X-rays showed the cause of his problems: he had been shot with a shotgun and had dozens of pellets embedded throughout his body. Due to h
is dense fur, no one had noticed the pellet injuries. Additional tests found liver and metabolic problems, probably from not having eaten much over an extended period.
“It was quite a shock to us all to find that he was shot, that his injuries were human caused,” Akhurst said sadly. “We initially wondered if he was just an older otter who was declining from natural causes, which made us wonder if we should even intervene. But once we realized that humans were involved, we switched gears to do everything in our power.”
Over the course of the next six weeks, Walter’s round-the-clock care continued. Only two shotgun pellets were removed from his body, because most of the entrance wounds had healed over, but he had two toes and part of his right flipper amputated. An oral surgeon also removed three broken teeth and conducted a complex root canal to save one of the animal’s canine teeth. Walter gained eleven pounds during that time on a healthy diet of shrimp, clams, and crab, and he was back to spending much of his day grooming himself.