by Todd McLeish
As planned, Tomoleoni briefly surfaced halfway between the boat and the otters. It allowed him to get a picture of the exact location of the otters, and it allowed the antenna of a radio attached to the headpiece of his dive suit to rise above the waterline, enabling Tinker to radio him and tell him the status of the otters and any other necessary information. Tomoleoni surfaced one more time even closer to the otters before disappearing for good. Tinker said that it is sometimes difficult to tell whether it is a diver surfacing or a harbor seal, so he sometimes gives instructions over the radio to a seal, thinking it’s Tomoleoni.
We then stared through our binoculars at the otters, not knowing exactly when the divers would breach the surface with their traps and set into motion an hour of hasty activities. As our arms became sore from holding our binoculars to our eyes, we wondered aloud about the delay. Had the divers lost sight of the otters? Were they tangled in kelp? What could provoke that five-minute delay? And then we saw the splash.
For the divers, timing is everything. If they reach the surface simultaneously, they have a better chance of capturing two otters, whereas a delay by one diver—even a slight one—makes it likely that the second otter will be alerted in time to escape. Which is exactly what happened. Kenner’s trap appeared at the surface first, and although the splash obscured my ability to tell how it happened, he succeeded in capturing his targeted otter. But Tomoleoni was a split second behind Kenner, and while it appeared to me that Tomoleoni’s otter leapt up and landed in his trap, the animal actually leapt away and escaped. The wave of one diver’s hand—I couldn’t tell who it was—signaled that the boat could approach, so Tinker pulled the Pursuit alongside the divers to retrieve the captured sea otter.
It was immediately obvious that the otter wasn’t happy. At the side of the boat, it hissed and fought aggressively to escape, repeatedly biting on the trap’s metal frame, attempting to push through the netting, and continuously spinning and trying to dive. Its efforts were fruitless. But it was the closest I had ever come to a wild otter, so although I felt bad for the unhappy animal, the moment was also quite exciting. Tinker identified it as a young female, which we would later learn was pregnant. She was an attractive chocolate brown with no apparent injuries or other concerns. Tinker and the divers lifted the trap from the water, set it over the open crate, and released the drawstring from the net; the otter dropped into the crate. I quickly closed the crate door, and we had our first otter securely stowed.
I asked the divers what went on beneath the surface during the capture process, and Tomoleoni said his scooter was wobbling throughout the dive, providing him with less than half the normal power output. That meant that he didn’t have enough speed to push through the kelp and keep up with Kenner as they surfaced together. Visibility was great, he said, but the large quantity of kelp the otters were resting on and his scooter’s power deficiency made it impossible for him to break through the obstructions to capture his otter. Kenner, on the other hand, called his experience “textbook” because it required only a short swim to the otters, he could see the animals well, and he captured his target. At most other sites, the divers have to swim more than three hundred yards through thick kelp and swells to reach the otters, so this one was easy by comparison. “This was like nursery school, it was so easy,” Tinker said. And besides, added Kenner, “the reflections off all of the salps in the water made the swim feel like I was in Star Wars.”
After a short run to the aquarium pier, we unloaded the otter-filled crate into the hands of a team of veterinary assistants and took on an empty crate.
* * *
THE LIVE SEA OTTERS captured that day are part of a long-term monitoring program led by Tinker and his predecessors. The veterinary team collects a comprehensive series of health measurements, similar to routine exams done on dogs, cats, and humans, after which the otters are implanted with a tracking device and released back into the wild. From that day forward, every tracked otter is monitored every single day for several years by a team of biologists and volunteers to learn about its movement patterns, social interactions, behavior, diet, and reproductive success. Combined with annual population surveys and mortality data collected from otters found dead on the shore, this record of daily sightings and activities provides tremendous insight into the lives and health of sea otters in California. Tinker said that none of the three data sets is particularly useful on its own, but putting them all together “is the most powerful thing that we do.” Many of the otters will eventually be recaptured sometime in the future, allowing the researchers to compare changes in the animals’ health. By knowing what the animals did from day to day, where they lived, and what they ate between captures, Tinker’s team is able to pinpoint the factors that affect each otter’s health and create a picture of the overall health of the otters in different parts of the state.
“The big picture is that this longitudinal data on individual animals provides us insight into what drives the population and how sea otters as apex predators are interacting with all of the other species here to affect ecosystem dynamics,” he said. “Without this monitoring data, what we’d know about sea otters, very optimistically, would be one-tenth of what we know today, and probably a lot less.”
He admitted that it will probably take years before he learns much from the otters we captured that day. But each animal is likely to eventually provide important insights that will help ensure the long-term survival of the species. And the ongoing monitoring activity and health data provide opportunities for many smaller research projects, like studies of territorial behaviors, reproductive success, or genetics.
* * *
AFTER RETURNING to the marina to fix Tomoleoni’s scooter, Tinker had a quick conversation on the radio with the spotters, and we headed a short distance away to the waters off the Monterey Bay Inn, where another group of resting sea otters awaited us. We could see the spotters watching from the deck of the inn as we maneuvered around a dead sea lion floating on a sturdy stalk of kelp and got into position for the next dive. For several minutes, we watched four resting otters—two wrapped quietly in kelp and two somewhat actively grooming and looking around. As we waited for them to settle, kayakers came very close to the otters, so close that Tinker said they were breaking federal law for disturbing marine mammals. We worried that the kayakers would startle the otters and we would have to abandon the effort, but the otters remained calm and the divers slid into the water. This time, however, the otters were amid a thicker forest of kelp, making it difficult for the divers to see the animals from underwater. After another long wait, Tomoleoni and Kenner retreated briefly to get another look at the otters from the surface, then moved in. With another big splash, they caught two animals.
When we delivered the first of the two sea otters to the aquarium dock, Renay and I climbed off the boat and followed the crate up a freight elevator and into the animal health laboratory, where veterinarian Mike Murray and six assistants and onlookers crowded around a small stainless-steel table that was ready to receive the otter. The room looked like a fancy version of the vet’s office where I take my cats—glass-fronted cabinets containing drugs and supplies, a table for the “patient,” and a high-tech scale. When the crate was opened, Murray, decked out in jelly-bean scrubs and a trim gray beard, grabbed the otter’s flipper while an assistant injected an anesthesia cocktail into the animal’s thigh. Then the crate was closed again for several minutes to let the drugs take effect. After lifting the limp animal onto the table, the assemblage collected measurements that were called out and written on a data sheet—weight, 34.1 kilograms; length, 134.4 centimeters; girth, 81.3 centimeters; canine tooth, 8.4 centimeters; tail, 31.9 centimeters; scapula, 17.4 centimeters; body temperature, 100.9 degrees Fahrenheit; respiration, 16 breaths per minute; heart rate, 130 beats per minute. After peering into the otter’s mouth, Murray added, “It also has a great personality and a fine sense of humor.” The otter was estimated to be eleven years old,
based on his grizzled appearance and the condition of his cracked, worn, and broken teeth.
Then an oxygen mask was placed over the otter’s head, and bags of ice were placed on his chest, under his arms, and on his crotch and flippers to keep him cool. Several vials of blood were collected from his jugular vein while Murray collected a smaller sample from a vein in the otter’s leg to test the animal’s blood glucose level—94 milligrams. Next a tube was placed down the otter’s throat and attached to a ventilator. When the oxygen hood was removed so the otter could be transported into the surgical ward, the hood was filled with tiny nasal mites that had escaped from the animal’s nose. “Tastes just like chicken,” said a smiling Murray.
* * *
THE TRANSMITTERS implanted into the sea otters we captured are the size of a small bar of soap and have been the primary technology used to track a wide range of animal species for close to thirty years. The device consists of a clear resin block containing three small batteries, an antenna, and an electronic device that transmits a pinging sound over a particular radio frequency that can be detected by a receiver aboard a boat. It collects no data. Instead, it transmits the signal to identify the animal’s precise location, somewhat like the GPS feature in many cars and cell phones. According to Zach Randell, a doctoral student at the University of California, Santa Cruz, who works with Tinker, the transmitter is temperature dependent. It broadcasts a signal twice every minute if the animal is alive and maintaining its normal body temperature, and one beat per minute if the animal is dead and cold. Dead animals are retrieved for studies of their body condition, health, and cause of death.
Some animals—though not those we captured that day—are also implanted with a device called a time and depth recorder, or TDR. It is a cylindrical piece of plastic a little larger than a cigarette that records how deep the animal is in the water every second. When recovered from the otter, it provides data that shows how often and how deep the animal dives below the surface of the water. “Between the TDR and observational data from our volunteers, we get a lot of data that can tell us exactly what each otter was doing from minute to minute every day,” Randell said.
The process of implanting the $800 transmitter into the otter we delivered to the aquarium began with a sterile lubricant being spread on its belly and combed in, allowing the surgical assistant to separate the fur and find the animal’s naval, where the incision would begin. Murray then entered the room in full surgical garb, and everyone became quiet. Only the sound of the beeping heart monitor could be heard. He made a four-inch incision and carefully cut through skin and muscle to make a small hole in the body cavity. In one quick motion, he grabbed the transmitter, slid it into the hole, and began to suture the incision. “I suppose I could have made it more exciting, but that’s really all there is to it,” he said. The longest part of the entire process was the suturing, which he did in four layers. “We don’t want him to come unzipped.” If it’s not closed well, his skin won’t be well protected from the cold. “Suturing well helps me sleep at night,” Murray said.
During the surgery, a nurse collected nasal swabs and fur samples, while biologist Michelle Staedler punched a tiny hole in the skin between toes four and five of his left flipper and attached tag number 6300. She repeated the process on the right flipper with tag number 6987. The location of the right flipper tag identifies the animal’s gender—between toes four and five for males, between toes one and two for females. The color of the tag indicates to the scientists which research project the otter is involved in or where the otter lives. The plug of skin tissue removed for the tag was saved for later DNA analysis. A passive integrated transponder, or PIT tag, an electronic device the size of a grain of rice that is commonly used to identify domestic dogs and cats, was also injected into the animal’s leg. The entire surgical procedure took no more than twenty minutes.
The otter was then placed back in the crate, given a shot to reverse the anesthetic, and within thirty seconds was awake and ready for release. Back aboard the boat, we drove to the same spot where we had captured the sea otter, set the crate on the edge of the boat, and opened the door. The otter slowly climbed out, looked over his shoulder at us, and swam away. He resurfaced next to what we believe was the same group of animals he had been resting with prior to capture, as if nothing had happened.
* * *
WE THEN RETURNED to an area just east of the aquarium, in front of a new hotel, where two otters were resting in the kelp one hundred yards offshore. The divers prepped their gear, and we again waited to ensure the otters remained calm. Once again, however, a kayaker drifted too close, and although the otters initially looked like they were going to sit still, they slowly rolled over and dived.
So we moved a bit to another group of three otters that the spotters said had been resting quietly for more than an hour. After only a brief period of waiting, the divers slipped into the water and captured one of the two otters they targeted. Again, Kenner hit the surface first and successfully captured a young female otter, but Tomoleoni’s targeted animal leapt upward and away from the trap. We dropped off the newly captured otter at the aquarium and picked up the previous female for release. When the crate was opened, she slid out quickly, dived deep, then surfaced twenty yards away without looking back.
We repeated the process one more time back where the kayaker had disturbed the group of otters an hour previously, and the divers succeeded in capturing two more animals to finish out the day’s activity just as the sun was dipping beneath the horizon. It had been a very long day, but with six otters captured, Tinker considered it a tremendous success.
Chapter 4: Shifting Paradigm
SANTA CRUZ, CALIFORNIA
LIKE EVERY one of the two dozen sea otter researchers I’ve met, Tim Tinker didn’t start out with any particular passion for studying sea otters. He grew up in Ontario and earned a master’s degree studying gray seals in the Gulf of Saint Lawrence. At a marine mammal conference in Texas in the early 1990s, he met Jim Estes, whose early investigations of sea otter ecology are the foundation of nearly every sea otter study in recent decades. During the conference, Estes recruited Tinker to help him study sea otters in the Aleutian Islands, and a week later Tinker was dropped off on Amchitka Island for four months. Tinker was the right man for the job: he was interested in ecology, enjoyed studying animal behavior and population biology, and wasn’t averse to conducting remote fieldwork. When he completed his stint on Amchitka Island, Estes offered him another year of sea otter work in the Aleutians, beginning a long-term working relationship that continues today.
The first thing I learned about Tinker, well before I observed him trap otters on the Pursuit, is that he is a hard man to reach. It took me a few months. But when I finally tracked him down at a meeting in Alaska, he remembered my messages and could not have been more generous with his time. The other thing I learned about Tinker—this time from his fellow sea otter researchers—is that he makes their heads hurt. That’s because his expertise at creating and interpreting complex computer models is way over the heads of nearly everyone with whom he works. I understood their predicament when I first sat down to speak with him. I’m still not sure I understand some of what he said.
Tinker’s research takes place everywhere and anywhere sea otters are found, including Russia, the Aleutian Islands, Prince William Sound, Southeast Alaska, British Columbia, and especially California. But his home base is the Long Marine Laboratory at the University of California, Santa Cruz, which doubles as the Santa Cruz Field Station of the US Geological Survey’s Western Ecological Research Center and has become the world’s capital of sea otter research over the last forty years. Nearly every sea otter biologist I met had a connection to the university, either as a professor, graduate student, or alumnus. It seems that everyone who wants to study sea otters eventually finds their way to Santa Cruz.
When I finally sat down to talk with Tinker in his office, he half smiled at me and sai
d, “I’m kind of evil.” It was his way of explaining that he is not like those at aquariums who rescue stranded sea otters and care for them for months at a time. He’s also not like the pathologists who examine every dead sea otter to determine its cause of death. “I don’t really care about the fate of individuals. I look at the really big picture of things. I’m looking at what makes an entire population grow at the rate it does.”
Unfortunately, the sea otter population in California has been growing very slowly. And that has been the main problem that Tinker and Estes and many other sea otter biologists have been worrying about for many years. They were certain that something was happening in the population to keep their numbers down, but years and years of study could not uncover what was causing the slow growth. In Southeast Alaska, the sea otter population grew at more than 15 percent per year for fifty years after they were reintroduced to the region in the 1960s. But in California, the growth rate has been just 5 percent per year since the 1930s, and lately the population has barely grown at all. The scientists compared California birth rates and mortality rates and any number of other issues with the comparable rates in Alaska, Washington, and British Columbia, where growth rates topped out at 20 percent in some years, but never did they identify a cause for California’s slow growth. Yet they continued to seek answers.
