Getting Out the Oil: TWENTY YEARS AFTER EXXON VALDEZ, NEW WAYS TO TREAT OILED SEA OTTERS by The Wildlife Society

Getting Out the Oil TWENTY YEARS AFTER EXXON VALDEZ, NEW WAYS TO TREAT OILED SEA OTTERS By David A. Jessup and Michael H. Ziccardi, Ph.D.

Credit: Sharon Toy-Choutka

David A. Jessup is Senior Wildlife Veterinarian with the California DFG’s Office of Spill Prevention and Response.

Credit: Alison Kent, UCD

Michael H. Ziccardi, Ph.D., is Director of the Oiled Wildlife Care Network, Wildlife Health Center, U.C.-Davis.

ust past midnight on March 24, 1989, while sea otters were plying the icy waters off Alaska, the supertanker Exxon Valdez struck Bligh Reef and began to leak North Slope crude into the pristine waters of Prince William Sound. A spill of nearly 11 million gallons eventually spread over 1,000 kilometers of ocean and coastline. Tens of thousands of marine birds and thousands of marine mammals—including as many as 6,000 sea otters—died as a result of the disaster (Hofman 1994). As the drama played out on television, millions of people saw oiled sea otters struggling to survive, as well as heroic efforts to save them. The Valdez disaster directly inspired the Federal Oil Spill Prevention Act of 1990 and California’s comprehensive Oil Spill Prevention and Response Act, both of which require intensive planning for oiled wildlife care. Treatment capabilities have improved enormously in the 20 years since the spill, most recently the methods to speed the recovery of sea otter fur when it must be cleaned. This new knowledge will prove critically important as long as oil-filled tankers cross the seas, putting marine life at risk.

Three subspecies of sea otters (Enhydra lutris) range from eastern Siberia to California (see map). Two population groups are listed as threatened under the Endangered Species Act (ESA): southern sea otters (Enhydra lutris nereis), which live off the California coast, and the population of northern sea otters (Enhydra lutris kenyoni) that live along Alaska’s western Aleutian Islands. Before the Exxon Valdez spill, populations of northern sea otters in Alaska were robust, believed to number between 100,000 and 150,000 (Calkins and Schneider 1985), with an estimated 30,000 otters living in Alaska’s Prince William Sound. The Exxon spill took an immediate toll. In Prince William Sound alone more than 5,000 otters may have died as a direct result of the oil spill (Garrott et al. 1993). Some biologists predicted that otter populations would quickly recover, but that optimism was unwarranted. In some heavily oiled areas, otter populations still have not recovered. Even in the western Aleutians, which were almost completely unaffected by the spill, sea otters have declined in some areas by 95 percent since 1989, prompting that population’s ESA listing in 2005. Once exposed to oil, sea otters can die from the effects of inhaling the volatile components of crude oil and from multi-organ damage after grooming and ingesting oil. In addition, the unique anatomy and physiology of sea otters make them the most susceptible of all marine mammals to the detrimental effects of external oil contamination. The smallest marine mammals in North America, sea otters possess the largest surface-to-body volume ratio, have relatively little body fat, and have no subcutaneous blubber layer. They therefore must consume about 25 to 30 percent of their body weight in shellfish daily just to maintain their

Current Sea Otter Range ESA listed as threatened Non-listed populations Oil tanker routes and terminals

Sea Otter Care Facilities Seward, AK Sausalito, CA Santa Cruz, CA Monterey, CA San Diego, CA Map: Michael Harris, California Dept. of Fish and Game

Oil’s Lethal Toll

The Wildlife Professional, Summer 2009

Three subspecies of sea otters—Siberian, northern, and southern— range from Japan and Russia to Alaska and California. The western Aleutian population of northern sea otters are listed as threatened under the ESA, as are all southern sea otters, which live off the California coast in close proximity to major oil terminals.

weight and core temperature. Yet they live in waters that are typically 50 to 70 degrees F (10 to 21 C) below their core body temperature, which varies between about 98.5 and 102 degrees F depending on activities (Williams and Davis 1995).

fatal. Of the otters handled during the Valdez spill, 123 (35 percent) died, 196 (54 percent) were cleaned and released, and 37 (11 percent) were judged to be unlikely to survive if released and therefore sent to public display facilities (Hofman 1994).

Maintenance of thermal stability and effective foraging become nearly impossible if petroleum contaminates an otter’s fur. Densest of all mammal fur, otter pelts have an intricate web of interlocked hairs that trap air to provide insulation. Normally sea otters spend from 20 to 30 percent of their waking hours grooming to keep their coats in optimal condition to trap air. When oil penetrates the fur it disrupts the interlocking of the hairs, breaks the surface tension, and displaces trapped air, causing insulation to decline. Otters coated in oil therefore can quickly experience potentially lethal hypothermia, manifested by shivering and holding flippers out of the water to help retain heat.

The response to the spill ignited significant controversy within the biological community as to whether, how, and at what expense oiled animals, especially sea otters, should be treated. In 1989 the cost to build temporary care facilities and treat otters hit $18.3 million, or about $80,000 per otter (Estes 1991).

To offset heat loss and maintain core body temperature, oiled otters have three options: increase their already high metabolic rate, increase food consumption, or leave the water. The first two alternatives are only marginally possible and take many days to occur. The latter two directly conflict. If an otter leaves the water it can’t forage, which leads to starvation and potentially lethal hypoglycemia. In trying to stay warm by grooming out cold areas of their coat, otters ingest petroleum constituents, which are irritating and/or toxic to vital organs like the liver, kidneys, brain, lungs, and gastrointestinal tract. Cleaning oil off otter fur is therefore essential to the animal’s survival.

A Better Way to Wash In 2004 the California Department of Fish and Game’s (CDFG) Office of Spill Prevention and Response (OSPR) began exploring the physiology and thermal consequences of washing sea otters in various water types and temperatures before placing them back in sea water. Electron micrograph imagery shows that the traditional tap-to-sea-water approach leaves salt crystals and soap scum in otter fur, which inhibits the interlocking of hairs and development of surface tension necessary to restore water repellency and insulation (see box, page 38). In addition, infrared photography, or thermography, clearly shows that washing even healthy, unoiled sea otters completely disrupts the insulating qualities of their hair coats. OSPR researchers hoped to develop more-effective washing practices to shorten the time for recovery of waterproof pelage, thereby potentially increasing otter survival rates and decreasing costs. For purposes of the study, they used healthy, unoiled adult male sea otters that had been declared “unreleasable” by the U.S. Fish and Wildlife Service (FWS).

Inadequate Response in ‘89 In 1989 responders were unprepared to contain spilled oil or clean oiled animals. The federal government did not assume direct authority, and contractors had to learn on the fly how to construct treatment facilities and rehabilitate sea otters. At that time oiled sea otters were washed with diluted dishwashing liquid, rinsed in warm hard tap water, and then placed in ambient sea water of about 36 to 42 degrees F. With that treatment it routinely took 10 days to two weeks for the water repellency of washed sea otter hair to return to normal (Davis and Hunter 1995). Because some otters were already hypothermic and in shock, they fed poorly in captivity, and those that had little body fat often went into a catabolic downward spiral that proved

Credit: Sharon Toy-Choutka

As part of a study to determine heat loss after washing, David Jessup and his team washed a healthy otter from the shoulders down, then photographed the wet animal (left). Immediately afterward they made an infrared thermography image of the same otter, which shows heat loss of roughly 80 degrees F from the wet areas.

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The Physiology of Fur An electron micrograph image of sea otter fur (right) shows flecks of salt and soap scum. These are signs of inefficient washing or rinsing, and they could be lethal for otters. Sea otters depend on clean, water-repellent fur for insulation against cold ocean water. Their dense pelts are composed of stout guard hairs and finer under-hairs—up to 650,000 hairs per square inch (FWS). Vigorous grooming causes a ratchet-like interlocking of hair shafts and “felting,” which helps trap air. Indeed, air space forms approximately 80 percent of the pelt’s volume (Williams et al. 1988). Credit: Robin Dunkin The hydrophobic nature of the hair, as well as the water’s surface tension, keep that air within the pelt, providing insulation like a dry suit (Weisel et al. 2005). When oil penetrates fur, displacing entrapped air and disrupting the interlocking of under-hairs, pelage insulation can fall by 70 percent (Williams and Davis 1995). Soap scum and salt crystals can cause the same disruptions to interlocking and surface tension. When insulation fails, potentially lethal hypothermia quickly follows.

In the first phase of the study, researchers standardized variables such as detergent concentration, washing and rinsing time, water temperature, room temperature, and drying time and temperature, all of which might influence core body temperature, recovery of coat insulation, and normal behaviors during and immediately after washing. The best results came from washing an anesthetized otter for 30 minutes with a 2.5 to 4 percent concentration of dishwashing liquid, rinsing it for an hour in fresh, soft water (four grains of hardness per gallon) warmed to 80 or 90 degrees F, toweling off surface water, and drying the animal for 10 minutes with a high-volume warm-air dryer. Phase two focused on the best recovery medium to use after washing. Researchers used the method described above to wash two well-acclimated male sea otters and then released them into four different types of water: ambient seawater (roughly 44 degrees F), warm seawater (about 60 F), ambient

The Wildlife Professional, Summer 2009

soft fresh water (about 45 F), and warm soft fresh water (62 F). Rest periods between trials varied from two to six months. The ambient sea water trial was repeated towards the end of the project to test whether the otters may have learned behaviors during the progression of trials that would help them more quickly regain waterproofing, but researchers identified no such adaptive behaviors. To monitor and record thermal responses in washed otters, researchers implanted passive integrated transponder tags the size of a grain of rice below the otters’ skin to relay information about body temperature after washing. Infrared thermography showed heat loss in washed animals, and small VHF radios implanted into the otters’ abdomens allowed researchers to record core body temperature and track outcomes over time. These data showed that softened fresh water (either warm or ambient) was by far the most beneficial recovery medium. It greatly encouraged healthy grooming behaviors, which enabled washed otters to recover their normal insulation and water repellency two to three times faster than in either warm or ambient sea water. Sea otters in the studies needed five to eight days to recover in sea water (comparable to the best results from 1989), but only two to three days in softened fresh water. Although warming the water (salt or fresh) seemed to make otters more comfortable and willing to groom, warming was only marginally statistically significant. Further work has shown that sea water can be added back into pools gradually after a day or two without negatively affecting improved recoveries, thereby readying otters for return to the ocean. A third phase of trials involved simulating exposure to oil during washing and recovery. Researchers first dipped anesthetized otters in an agitated mixture of canola oil and sea water. They massaged this mix into the fur to mimic the effects of grooming. They then washed the animals the same way as in previous trials and released them into warm (62 F) softened fresh water. These oiled otters recovered just as fast (in about two days) as the unoiled otters subjected only to washing. Thus oiling the otters (albeit with non-toxic oils) did not slow the time it took the animals to regain normal waterproofing of their coats, an encouraging result. By cutting recovery time at least in half, the methods described in this research, which we hope to publish later this year, have already led to a rewriting of sea otter washing protocols regarding the

type and temperature of wash, rinse, and recovery water. This research has also led to physical changes in otter care facilities, such as the addition of industrial-size water softeners and heaters for pools. Although trained captive sea otters such as those used in the trials do not suffer the many stresses and pre-existing health problems of wild sea otters, they do demonstrate what can be done to reduce washing and captivity-related physiologic stress, reduce caloric needs, and shorten the time required for fur to recover its water repellency. Improved recovery times should also shorten overall holding time, thereby decreasing costs and increasing the numbers of otters that can be cared for during a crisis.

Test Case for Science In February 2009 these new methods got an unexpected trial run. The Monterey Bay Aquarium received a sub-adult female southern sea otter tarred over 50 percent of her body with Monterey formation crude oil (see sidebar). After being medically stabilized and transferred to CDFG, the otter received the kind of care and treatment used during the research trials. Because she was seriously emaciated and rapidly losing body heat, her rinse temperature was increased to 100 degrees F and warm, soft-water pool temperatures were increased to 88 degrees F. The otter (nicknamed Olive) responded as well as the research otters, which had been in excellent body condition. After 53 hours in contact with warm, soft fresh-water pools that were progressively cooled over several days, Olive had regained about 90 percent of her waterproofing and her core temperature was stable. Caregivers used infrared thermography to closely follow improvements in Olive’s coat. The overall cost for care was about $5,000, considerably less than what it cost in 1980. A celebrity test case, Olive gained fans on Facebook, which followed her progress. Beyond improvements in washing techniques, in the last 20 years researchers have also defined baseline health of otters and improved anesthesia, blood gas monitoring, and treatment of infections, all of which improve chances of survival. We now know, for example, that low doses of fentanyl (0.22 to 0.33 milligrams per kilogram) combined with midazolam and reversed with naltrexone will anesthetize an otter sufficiently for cleaning with minimal side effects and a reduced incidence of seizures, cyanosis, or renarcotization (Monson et al. 2001). Small, accurate hand-held pulse oxymeters now allow constant monitoring of an otter’s vital signs and oxygen saturation.

The Story of Olive On February 21, 2009, a female sea otter coated in tar washed ashore at Sunset State Beach on Monterey Bay. Rescued and taken to the California Department of Fish and Game’s Marine Wildlife Veterinary Care and Research Center (MWVCRC) in Santa Cruz, the otter needed urgent care, and became a test case for science. After using olive oil to make the tar soluble enough to wash out, staff nicknamed the otter “Olive.” They then began treating her with the new washing techniques developed by MWVCRC veterinarian David Olive awaits washing. Jessup and his colleagues. The team anesthetized Olive and meticulously washed her with dishwashing liquid and warm soft water to remove tar, soap, and salt, any of which could prevent the fur from recovering its ability to trap air for insulation. They used highpowered, warm-air dryers on the pelt, then revived the otter David Jessup, right, helps clean. and released her into a pool of warm, fresh water that was gradually cooled. After about six weeks in recovery on a high-calorie diet of prawns, clams, and abalone, Olive appeared healthy enough to earn her release into the wild. With much fanfare she was set free near the spot where she was found on April 7, 2009, 20 years after the Warm air dries the pelt. Exxon Valdez oil spill. A team from the Monterey Bay Aquarium still tracks Olive’s movements through a temperature-sensitive radio implanted in her abdomen. Eating and mating normally, Olive marks a success for science, and hope for the roughly 2,800 threatened California sea otters that still face environmental hazards. Olive recovers before release. Credit: All photos couresty of Sharon Toy-Choutka

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In 1989 there were no facilities for the treatment of oiled sea otters, and many died or became sicker waiting for care. Much of the new research has been made possible by the development of state-of-the-art treatment and care facilities and the provision of research funding for oiled otters, seabirds, and other animals. The Oiled Wildlife Care Network (OWCN) in California, a partnership between CDFG and the Wildlife Health Center at the University of California-Davis School of Veterinary Medicine, has about two dozen facilities for treating oiled wildlife. Specialized care for sea otters is available at four OWCN sites including the Monterey Bay Aquarium, Sea World in San Diego, the Marine Mammal Center in Sausalito, and the Marine Wildlife Veterinary Care Research Center in Santa Cruz, location of our otter-washing research trials and site of Oliveâ&#x20AC;&#x2122;s care and recovery. The Alaska Sea Life Center in Seward also offers otter care. OWCN facilities can treat more than 100 oiled otters at a time, a capability that oil-transport companies can cite to meet their legal obligation to provide care for otters that may be oiled in a spill. Despite all we have learned about caring for oiled otters, spilled oil will continue to have long-term consequences for wildlife. Once in the food chain it can debilitate marine life for many years, slowing natural population recovery to a greater degree than previously estimated. Research shows lingering negative health effects related to the Exxon Valdez oil spill, resulting from toxic petroleum constituents in the food web that damage ottersâ&#x20AC;&#x2122; organs (Bodkin et al. 2002, Peterson et al. 2003). Such chronic, delayed effects can be as serious to an otter population over time as acute effects. Oil from Alaska is still shipped to refineries in California, where a single large tanker spill could cover an area greater than the entire range of the southern sea otter, jeopardizing its potential for population recovery (Brody 1996). The FWS recovery plan for the southern sea otter cites a catastrophic oil spill as the most likely stochastic event threatening population recovery. This makes recent advancements in treating oiled otters all the more crucial for long-term survival of the species.

For an abstract and bibliography, as well as video of researchers washing a sea otter, go to www.wildlife.org.

The Wildlife Professional, Summer 2009

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