The Seward Otter Rescue Center received over 150 sea otters (Enhydra lutris) during the period from May 1989 through September 1989. During the rehabilitation period, the sea otter proceeded through a series of pool systems. This system provided an environment for the otter to stimulate its natural oils and recondition its coat before returning to its natural habitat. Using methods developed by Dr. T.A. Gornall and Jeffrey A. Rash, from several overseas transports of otters, a criteria was developed to "grade" coat conditions at the center and provide valuable behavioral information in relation to coat condition. It was found that with a study of grooming behavior, amount of time spent in the water and a chemical analysis of hair samples, we could correlate the "grade" of the coat to the degree of oiling of the otters coat by the Prudhoe Bay crude. This study will also show the relationship between medical condition and coat condition of the sea otter at specific times during the rehabilitation process at the Seward Otter Rescue Center.

Introduction

On March 24, 1989, the oil tanker Exxon Valdez ran aground on Bliqh Reef in Prince William Sound, Alaska, spilling over 11 million gallons of Prudhoe Bay Crude Oil into the surrounding waters. During the next few months many organisms, ranging from plankton and salmon fry to bald eagles and sea otters (Enhvdra lutris) were affected. Contamination of the sea otters pelage by this crude oil destroys the integrity of the otter's natural oil coat and the protective air layer. This allows water to penetrate the otter's skin (Kenyon, pers.comm.1983; Davis, et.al.1988). When the otter begins to feel the effect of coat degradation, it begins to automatically groom, thus trying to provide an air layer between the guard hair and skin. As the otter grooms, it not only spreads the contamination to other areas of its coat, but begins ingesting the oil thus lessening its chances of survival. Some otters were so affected by the crude oil that they did not survive more than a few days before the affects of the contamination took its toll.

Many factors need to be considered when trying to rehabilitate sea otters from crude oil contamination. Water temperature, humidity of air just above the water, pool space, feeding regime and haul-out availability play important roles (Gornall, Nakajima pers. comm. 1983). The pool system set-up in Seward, Alaska provided many of these. This system also allowed staff members and volunteers to compile behavioral information on the recovering otters. Hair samples from oiled, washed and non-washed otters were also able to be collected for future examination of the effects of crude oil on the integrity of the sea otter coat. Both the behavioral observations and hair samples provide us with valuable information on the sea otters ability to recover from such a disaster.

Methods

Animals

A total of 176 adult sea otters were brought into the Seward Otter Rescue Center. Upon arrival, the otters were examined by the veterinarian and husbandry staff to determine general health and oiled status of the otter. Three (3) hair samples were taken from 86 otters during this period, one from the back of the neck, xyphoid region and hip region. Each otter was then tagged and placed in a slide top cage to await further evaluation.

Otters of all age and sex range were brought into the center. Of the adults, 137 were female, 39 were male. The rescue center also treated a total of 14 sea otter pups, four of which were born at the center.

Pool System Design

The otters behavior was observed during the five stage pool system at the Seward Otter Rescue Center.

1.  Intensive care unit - directly after admitting or washing

2.  Single haul-out tote 4' x 4' x 2'

3.  Double haul-out tote 4' x 4' x 2'

4.  Large pool with haul-out 11'x 5'

5.  "Duck pond" or pond facility with haul-out 12' x 8' x 14'

Each of these stages provides the otter with a varied degree of water, capacity and allowed the staff and volunteers to closely monitor the otters progression or regression.

Each of these stages also provided us with a "flow system,'' corresponding to each individual otters behavior. The intensive care unit allowed the otter to recover from anesthetic, without access to water, and permitted observation of this behavior. The single haul-out tote provided for observation of the beginnings of coat recovery, even though this type of tote did not promote normal grooming behavior from the otter.(Gornall,1983). The otters were allowed to have access to haul-out and circulating salt water 24-hours a day, but were indoors in order for monitoring of health to be a top priority. The double haul-out tote provided exposure to the outdoors, other otters and a more intensive study of grooming and coat condition. Neither of the above systems provided a sufficient depth or proper humidity of air above water surface. Otters were placed in pools according to behavior, sex, health status, and coat condition. Feeding behavior was also taken into consideration at this time, but this is directly dependent on the otters coat and grooming grade. The pond facility supplied greater depths and a cooler humidity of air above the waters surface to be achieved, both of which are essential to otter coat recovery (Gornall, pers comm.1983).

Behavior Observations

The behavior of each otter was recorded at 15-minute intervals for a total of 18 hours per day. These observations were used to determine the percentage of time spent autogrooming (self grooming), allogrooming (grooming another otter), swimming, diving, nursing, resting and sleeping. These behaviors were divided into "in-water'' and "hauled-out" behavior. The sum of the percentages of the time spent in each behavior equals 100%. Behaviors such as net-biting (related to stress), shivering and aggression were also recorded in a written comments section of each animals chart. These behaviors also played a major role in coat rehabilitation.

Grooming Gradation

The following gradations are specific for the Seward Otter Rescue Center. These gradations were developed by the author during 1982 and 1983 Sea Otter captures in Cordova, Alaska (Nakajima, pers. comm., 1983). Percentages for grooming behaviors differ in both captive and wild otters (Packard and Ribic 1982).

The otter was designated by the following grooming "grade" if the behavior was within the following parameters: 1= Poor, 2= Average, 3= Good

1.  Poor grooming behavior: Otter spends less than 15% of the day grooming. When grooming, takes place on the haul-out it is concentrated on the muzzle, face and neck region. If in the water, otter only grooms face slowly with no pinwheeling lateral roll or augering (anterior/posterior roll).

2.  Average grooming behavior: Grooms between 15-25% of the day. Starting to groom chest and shoulder area. When on haul-out grooms chest and arm area by blowing air into that region. IV in water, vigorous grooming behavior by augering, then pinwheeling with air being blown into chest.

3.  Good grooming behavior: Grooms between 25-60% of the day. Grooming hindquarters and back area. When a haul-out, grooms entire body and coat hairs should spike and/or point over entire body (depending if otter is wet or dry). When in water, vigorous grooming of back by periscoping (vertical axial roll) and pinwheeling. Vigorous swimming and augering also occurs.

Coat Gradation

The otter was designated with the following coat "grade" if the coat was within the following parameters: 1= Poor, 2= Average, 3= Good

1.  Poor Coat: The coat guard hairs, when wet only point from the head to the base of the neck The coat on the rest of the body is matted and damp. The coat stays damp for a period of time greater than 45 minutes when otter is hauled out. When otter is swimming, no beading or rolling of water occurs on any portion of the coat below the base of the neck.

2.  Average Coat: The coat guard hairs, when wet, only point from the head to mid-back and mid-abdominal region. When dry, the coat should spike at 40-60 degree angles. Coat should loft in spiked areas (presence of air layer). Upon swimming, the water should roll and bead off of the otters coat in pointed areas.

3.  Good Coat: Entire coat should point when otter shakes after getting out of the water. When dry the coat should spike at 75-90 degree angles and entire coat should loft. Coat should dry within 10-20 minutes. When swimming and grooming in the water, water should roll and bead off the entire coat. When sleeping in the water, the otter should be 50% "floating" above water line. Otter should be able to roll in the water horizontally and keep front paws, hind legs and tail out of the water.

Movement through Pool System

To ensure consistent grading of otters in the rehabilitation center, we conducted a seminar for the administrative, veterinarian and husbandry staff. This allowed supervisors to make daily written reports on each otter and allow the otter to move through the pool system based on these reports (Appendix 1).

Along with these husbandry reports, veterinarian reports were, also considered in the progression or regression of the Otters through the pool system. Factors such as weight gain or loss, medication, blood chemistry and injury were just a few of the parameters involved in rehabilitation of the sea otter.

Results

Time Budgets

Over 20,000 hours of behavioral observations were tabulated from 117 otters during a period from June 15 to August 15, 1989. The range of behavioral percentages varied from otter to utter. Due to the special circumstances, a final average of the otters behavior cannot be measured. The results tend to reflect the varied degree of behaviors encountered at the rehabilitation center. (See Chart 1)

Each otter required specific behavioral needs, but the one constant that was seen throughout the rehabilitation process was the autogrooming behavior. The high degree of incidence of this behavior was an integral part of the recovery process of the otters damaged coat. Comparing these ranges to captive and wild otters shows the special circumstances that existed in Seward, Alaska (Estes 1982; Rash 1982). (See Table 1)

Table 1 - Comparison of Seward Otter Rescue Center behavioral ranges to captive and wild behavioral average percentages

Allogrooming

During the period of behavioral observations, four mother-pup pairs were at the center. Allogrooming occurred between mother and pup 95% of the total time observed. The remaining 5% of the allogrooming budget occurred between "bonded" pairs of otters. These were otters that remained in the same pools throughout their rehabilitation period. Since many of the otters were moved quickly through the pool system, bonding occurred infrequently.

Autogrooming

The high percentage of autogrooming took place in the early stages of coat rehbilitation, then decreased and leveled off as the coat remained in condition. (See Graphs I, II, III). The majority of the otters were in circulating salt water pools 48 hours after washing and complete drying. This allowed almost immediate stimulation of natural oils by autogrooming and thus beginning of coat condition recovery. (Chart I)

Graphs I, II, III. Comparison of Auto Grooming, Coat Grade, Grooming Grade.

Figure 1.

Figure 2

Figure 3.

Swim

Swimming behavior was not observed until the otter reached the pool and "duck pond" stages. The single and double haul-out totes did not allow the otter proper space for the behavior to occur. Swimming primarily took place after feeding and as a part of the grooming process. (Chart I)

Chart I. Seward Sea Otter Behavioral Percentages, Coat Grade and Groom Grade (split into 2 parts for space and clarity)

Editors Note: The chart is difficult to read because of the headings but it was included from the pdf for your reference.

Click on the chart to see a larger view

Chart 1.

Chart 1 (con't).

Dive

Diving behavior was observed directly after feeding at the "duck pond" stage. The depth of this stage, 14 feet, allowed the otter two situations (1) to dive for food that was on the bottom of the pool and (2) to allow air pressure to compress and contract the air layer between the coat and skin to aid in grooming (Chart I)

Eat

The feeding schedule was set up to give the otter the optimum amount of caloric intake during the early stages of coat condition recovery. As the coat improved, along with the health of the Otter, feeding was dictated a behavior, so food intake was decreased. The primary foods given to the otters were squid, white fish, pollock clams and crab. During the rehabilitation period, a large majority of the food was not eaten and an accurate record of actual intake proved to be very difficult. (Chart I)

Coat and Groomming Gradation

Chart I shows the relationship between coat grade and grooming grade. These grades were taken independently of the behavioral observations. Husbandry volunteers recorded behavioral observations and husbandry supervisors conducted coat and grooming grades. Relating the behavior to the coat and grooming grade shows the otters improvement in coat and grooming grade. Progression of the otter through the pool system went accordingly. The "grades" were set-up for two reasons. One was to give a correlation between the otters condition and the pool stage it was moving through. The second was to give the veterinarian and husbandry staff a quantifiable indication to correlate to the otters Overall condition. The behavioral percentages were not available during the centers operations.

As a result of this system, the staff was able to determine when an otter was able to move to the next pool stage and when it could be transferred to the pre-release facility in Homer, Alaska.

Discussion

During the compilation of the behavioral data at the Seward Otter Rescue Center, many variables existed that caused "unusal" behaviors in the otters. Factors such as the oil itself, capture, water quality at the center, human influence, weather, medical all contributed to the otters rehabilitation The main body of data collected should be looked at closely and interpreted as a "special" situation. Many of the figures presented in the final behavioral analysis will show that each specific otter had very specific needs and problems. Being able to grade the coat and grooming behavior made the observations a key into understanding the otters behavior in this type of situation.

A pattern of rehabilitory grooming in salt water started to be observed. The otter would begin at the top of its head and within sly days would complete the rehabilitative process by grooming at the base of its tail. Observing this process develop with several otters, the veterinarian, husbandry and administrative staff began to understand what is required for a sea otter to recover from such a tragedy. It also allowed the otter to move through the pool system, thus moving closer to final release back into Prince William Sound.

For otters that were not washed, the average time for a grade 3 coat to appear was four days. At this time, the otter was grooming approximately 20% of the day, eating 10-13% of its weight per day and was either in a pool or at the duck pond. For otters that were washed, the average time for a grade 3 coat to appear was seven days. At this time, the grooming percentage began at 50-73% for the first two days, decreased to approximately 17-20% once grade 3 was achieved. From this, it appears that a recovery time of 3-7 days was necessary for an otter that was washed to recover its natural oils. Also seen in the behavioral observations was that when an otter was in the first stages of coat recovery, it would not sleep in the water. As the coat condition improved, the otters insulatory integrity would improve and allow it to spend more time in the water. Since low metabolic energy is expended during sleep (COSTA, 1084) the otter relies on the insulation to stay warm during sleeping periods,. Thus, as time progressed and the coat improved, the otters sleeping time in the water increased. This was also another key indication on how coat recovery was progressing.

An stated before, many factors were involved in the recovery of the sea otters. A system needed to be developed to aid the rehabilitation staff in the otters progress during recovery. The system discussed in this paper is not complete by any means. Improvements such as tests for degree of oiling on an otters pelage, better training of observers, stricter feeding regimes and less conflict between egos would greatly improve the system of recovery cur the otters.

Overall, the coat and grooming gradation of recovering sea otters needs to be implemented in the field as well. If continued monitoring of the population of Prince William Sound sea otters is needed, and eventual capture and recovery of more otters is needed, this "grading" system could be easily implemented along with the behavioral observation would prove useful in determining the coat condition of the otter.

References

1.  Costa, D.P.; Kooyman, G.L. Contribution of specific dynamic: action to heat balance and themoregulation in the sea otter. Enhdra lutris. Physiological Zoology 57(2): 199-203,1984.

2.  Davis, R.W.; Williams, T.M.; Thomas, J.A.; Kastelein, R.A.; Curnelli L.H. The effects of oil contamination and cleaning of spa otters (Enhydra lutris). II. Metabolism, Thermoregulation and behavior. Canadian Journal of Zoology 66(12):2782-2790, 1988.

3.  Estes, J.A.; Jameson, R.J.; Rhode, E.B. Activity and prey election in the sea otter: influence of population status on community structure. The America Naturalist. 120(2):242-258, 1982.

4.  Gornall, T.A. Letter to United States Fish and Wildlife Service. February, 1983.

5.  Kenyon, K.W. Observations of a sea otter and its environment at Izu Mito Sea Paradise, Japan. Presented to United States Fish and Wildlife Service, March, 1983.

6.  Nakajima, M. Letter to Federal Wildlife Permit Office, Washington, D.C. May, 1983.

7.  Rash, J. A. Behavioral observations of captive sea otters (Enhydra lutris). University of Washington Undergraduate research. June, 1987.