Chapter 15 – Introduction

The amphibious life history of pinnipeds and polar bears exposes them to spilled oil under circumstances not faced by sea otters. Their utilization of coastal and pack ice zones (which in many cases coincide with areas of hydrocarbon exploration, handling and transport) and the gregariousness of some pinnipeds, increase the potential for large scale impact. Furthermore, pinnipeds are a highly diverse group of mammals in terms of their global distribution, size, behavior, difficulty and risk of handling, and susceptibility to oil contamination. Any prediction of the impact on this group of animals must consider such variables as the type of oil involved, how much it has weathered, and the environmental conditions at the time. Light oil freshly spilled on a warm day is a threat to those breathing the vapors; heavy, weathered or residual oil in cold water is tenacious enough to restrict physical movement. In view of this, we caution against generalizing the findings of previous investigations. Rather, we encourage a thorough investigative approach to each new case to advance our ability to cope with inevitable future events.

The goal of this chapter is to provide workers with a practical framework for dealing with an oiled pinniped or polar bear. Oearly, the scope of potential scenarios of oil impact among these species is enormous. Our approach is to present a guide that must necessarily be tailored to meet local needs and animals. We assume that workers undertaking any such action will have a thorough knowledge of the life history and ecology of the species involved and the environmental and logistic conditions of the site. For a more detailed treatment of this subject, we refer readers to McLaren (1990) and St. Aubin (1990a) for pinnipeds and Stirling (1990) and St. Aubin (1990b) for polar bears.

We also provide a historical summary of oil spills involving the river otter, a fur-bearing mammal that may frequent coastal habitats. Information concerning the effects of oil contamination on this species is sparse. Therefore, we do not discuss the handling, cleaning, or treatment of oiled river otters. Readers are referred to Chapters 2 through 6 in this volume which address these topics for sea otters.

Categories of Oil Impact

Pinnipeds
Most observers of oiled pinnipeds have been unable to correlate the degree of oiling with the type of effect, its consequences, or even associated pathological changes. Nevertheless, we can examine the effects under four broad categories as a background to developing specific action plans. The impacts can be summarized as: a) fur/hair entrapment, b) irritation of eyes, mucous membranes and integument, c) ingestion/ inhalation and systemic effects, and d) behavioral disturbances.

(a) Fur/Hair Entrapment. The direct physical effects of oil entrapped in fur or hair may be severe enough to cause difficulty in swimming, plug nasal passages, and lead to suffocation and drowning. The degree of effect will depend on the degree of oiling, the body surface involved, and the viscosity of the oil (Figure 15.1). Locomotory problems have been observed primarily in young animals such as harp (Warner, 1969) and gray seal pups (Davis and Anderson, 1976) which were so encased that their flippers stuck to the body and the animals drowned. Impaired movements of eyelids and vibrissae may also be damaging (St. Aubin, 1990a). Plugging of respiratory passages with Bunker C oil reportedly killed seal pups at two major spills (Engelhardt, 1985). By contrast, some species, such as the northern elephant seal, can tolerate up to 75% surface fouling with no increase in mortality (Le Boeuf, 1971). In fact, all but one of fifty-eight oil contaminated elephant seal pups were resighted and found to be clean as little as one month later.

Oil fouling of pelage can produce aberrations in thermoregulation. Species that rely primarily on fur rather than blubber for insulation are clearly the most vulnerable. Fur also provides an ideal matrix for oil entrapment. Oil not only subverts the ability of fur to trap an insulating layer of air next to the skin, it also removes the natural oils that contribute to the waterproof quality of the fur (St. Aubin, 1990a).

Thermal demands are greatest for polar and subpolar pinnipeds. However, these species depend primarily on blubber for insulation with the result that external contamination causes little thermoregulatory stress. This distinction applies to adult animals only, as most neonatal pinnipeds initially rely on lanugo for insulation until they develop an effective blubber layer. The degree to which the pelt is compromised might also differ in molting animals, which experience some degree of physiological stress at that time.

Studies that measured changes in heat conductance through pelts have shown up to a 50% decrease in the insulating value of fur seal pelts oiled in vitro. A smaller decrease was found in oiled pelts from Weddell seal pups, and virtually no change was reported for the relatively poor insulating pelts of sea lions, bearded seals, and ringed seals (0ritsland 1975; Kooyman et aI., 1976, 1977). These findings do not address adaptive responses, such as shivering, alterations in metabolic rate and changes in peripheral circulation that may alter the thermal balance of living animals.

(b) Eyes, Mucous Membranes, and Integument. Oil is an irritant and can produce acute changes to the mucous membranes of the eye, oral cavity, respiratory surfaces, and anal and urogenital openings. The extent of damage will depend on the duration of exposure and the volatility of the oil. Most reports of oil-fouled pinnipeds include descriptions of excessive lacrimation, acute conjunctivitis, swollen nictitating membranes, corneal opacity (Figure 15.1), abrasion, and occasionally ulceration (e.g. Lillie, 1954; Spraker et aI., 1994; Smith and Geraci, 1975). The latter authors noted that most signs subsided when the animals had access to clean water.

The integument is less sensitive to contact with petroleum hydrocarbons, and pathological changes have rarely been reported in this organ. This may be due to the limited amount of available data. However, it is clear that animals with sparse pelage, and perhaps those during the molt, would be most vulnerable. Johnson (1983) noted that the creviced skin of the walrus may present special problems. The degree to which hydrocarbons can be absorbed across the integument is unknown, but Engelhardt (1985) felt it was unlikely to make a longterm contribution to tissue burdens.

(c) Ingestion, Inhalation and Systemic Effects. Ingestion of petroleum hydrocarbons adhering to the body surface is of little concern to pinnipeds, which groom using their flippers rather than their mouth. Thus, pinnipeds are only likely to ingest oil by: 1) accidentally opening their mouths while swimming, 2) sucking from an oil fouled nipple or playing with contaminated debris, and 3) ingesting contaminated prey. The first two routes are unlikely to lead to significant intake, and the third only applies to pinnipeds such as walruses and bearded seals, which consume benthic invertebrates, prey items that are known to accumulate hydrocarbons (McLaren, 1990).

Three limited studies demonstrated that phocid seals fed small quantities of oil were not obviously affected, even though the oil was readily absorbed through the intestine and distributed to body organs (Smith and Geraci, 1975; Geraci and Smith, 1976; Engelhardt, 1982). Conversely, oil in the gut and other organs was considered the cause of death in some gray and harbor seals stranded in France (Babin and Duguy, 1985). A causative relationship was not established in the latter study because of the autolyzed state of the carcasses. Regardless, most data indicate limited ingestion of oil by pinnipeds and an ambiguous clinical expression of metabolic toxicity from the ingested oil.

Hydrocarbons can also be absorbed by inhaling vapors. Experiments have shown that pinnipeds can accumulate petroleum hydrocarbons up to several ppm in blood and tissue after exposure to petroleum vapors (Engelhardt et aI., 1977). Following the oil spill from the Sanko Harvest, volatile compounds (particularly acetone) in the blood reached levels of between 30-90 ppm in fur seals that encountered the oil within twenty-four hours of the spill. This compares with 10-20 ppm in those animals exposed to the oil after it had weathered for more than seventy-two hours. Presumably, most of the volatile compounds had dissipated by this time. The concentrations of straight chain petroleum hydrocarbons in these same animals were less than 1 ppm (Gales, 1991). Based on these studies, it appears that inhalation or perhaps dermal absorption, rather than ingestion, were the primary routes of exposure in the fur seals. Once again it was not possible to establish a causal relationship between the degree of exposure (as determined from petroleum hydrocarbons levels in the blood) and mortality or tissue pathology (Gales, 1991).

Likewise, harbor seal pups exhibited few pathologic injuries and low mortality despite heavy external oiling following the EVOS (T. M. Williams et aI., 1990, 1994). As found for sea otters, total paraffinic hydrocarbon concentrations in the blood were variable for the pups (Figure 15.2). Values ranged from 22 ppm to 260 ppm (mean = 91%B127 SE ppm, n = 9). Although some of the seal pups had blood hydrocarbon levels above the calculated lethal threshold dose for sea otters (Chapter 4), none showed evidence of systemic toxicosis and all survived. The comparatively high survivorship of the seal pups is undoubtedly related to many factors including: 1) age, 2) species-specific differences in the uptake, metabolism, excretion, and storage of petroleum hydrocarbons, and 3) oil weathering prior to contact (T. M. Williams et aI., 1990).

It is likely that pinnipeds can detoxify absorbed hydrocarbons in a manner similar to other mammals, but may suffer damage to various organs if blood or tissue levels reach critical thresholds (St. Aubin, 1990a). We will discuss pathological and clinical findings in a later section and refer readers to Neff (1990), St. Aubin (1990a), Frost et al. (1994) and Engelhardt (1985) for general details of petroleum hydrocarbon toxicity and clearance in pinnipeds.

(d) Behavior. Oil spills can disrupt normal behavior by restricting movements to and from haulout sites. We do not know whether pinnipeds can detect oil, and if they can, whether or not they will avoid it. Although there is no experimental evidence that fouling with oil affects behavior in pinnipeds, there have been several anecdotal observations that infer some disturbances. Uncharacteristic swimming behavior, including vigorous head shaking, and swimming with the neck, head and trunk out of the water, has been noted in fur seals occupying a chronically polluted harbor (Shaughnessy and Chapman, 1984). Further, there is contradictory evidence that the mother-pup bond, for which scent appears to be an important component, may be disrupted. Observations of pup rejection by females has been noted, although the familial relationship between the observed animals was not known. Davis and Anderson (1976) reported that the mother-pup bond in gray seals was not affected by oiling, and noted that interrupting feeding to clean oiled pups may have had a greater impact on eventual mass at weaning than did the oiling itself. Heavily oiled New Zealand fur seal pups were observed nursing from females; there was no significant difference in the preweaning mass of heavily oiled pups and unoiled pups (Figure 15.3; Gales, 1991).

The behavior of different age classes of pinnipeds will determine their chances of encountering oil. For example, fur seal pups often congregate in tidal pools where there is little wave activity and oil can become trapped. The risk of fouling is greater for pups than for adults. Older animals tend to enter and leave the water in areas of higher wave activity where oil is physically repelled from the rocks. This basic difference in behavior explains why, after the sinking of the Sanko Harvest, an entire cohort of pups was contaminated, but no adults came into contact with the oil (Gales, 1991). There is clearly a need for quantitative studies to clarify the behavioral impact of oil fouling.

Polar Bears
A single laboratory study (0ritsland et aI., 1981) highlighted the vulnerability of polar bears to oil. Like sea otters and fur seals, polar bears depend on fur for insulation. Fouling of the coat increases heat loss, placing the animals in thermal stress. Polar bears also share the sea otter’s compulsion to maintain a clean coat, and will ingest any oil adhering to their fur. In two of three captive bears, the combined effects of metabolic stress and hydrocarbon toxicity had fatal consequences. Liver and kidney failure, anemia, and depressed lymphoid activity were noted. Secondary bacterial and fungal infections, which contributed to the animals’ demise, were evidence of stress-related impairment of immune function. It is unknown whether bears exposed in the wild would exhibit the same complications in the absence of the additional stress of captivity.

Capture and Restraint

Methods for capturing pinnipeds have been described in the literature (Geraci and Lounsbury, 1993). These techniques are generally restricted to the smaller otariids and phocids. Most methods rely on the use of nets to capture individual animals. Alternatively, mass capture of several animals is possible and has been described for fur seals. Chemical capture and restraint has been extensively reported and recently reviewed for marine mammals (T. D. Williams et al., 1990). Telazol(R) (8-9 mg/kg) has proven to be reliable and safe for immobilizing polar bears under a variety of field conditions (Stirling et al., 1989).

The potential for physically or chemically capturing marine mammals will depend on the number of target animals, the number of nontarget animals, and the terrain. Capture is usually limited to the land or ice as capture techniques at sea are generally considered hazardous. Because of the difficulties, it is important to be realistic when selecting target animals. Adult seals and bears that are fouled with oil and capable of avoiding capture by rapidly entering the sea should probably not be captured. Their condition can be monitored visually, especially if they are marked with projectile paint pellets or another identifiable tag.

We recommend capturing unoiled animals for use as a control group. These animals are especially useful for establishing normal values for body mass, clinical state, and hematological and biochemical constituents. Such controls also enable the researcher or veterinarian to differentiate between anomalies caused by the oiling and those associated with disturbance by the cleaning method. Control animals should be marked for the duration of the study.

Many chemical compounds used for capture or immobilization interfere with thermoregulation, compounding the problems already faced by an oiled fur seal or polar bear. The greatest concern is for animals in polar and subpolar environments. Any type of capture or restraint will impose some form of stress, which must also be considered when handling these animals. Fortunately, pinnipeds and polar bears generally tolerate capture and transportation better than sea otters; they do not appear as susceptible to the capture myopathy or “capture stress syndrome” described for sea otters (Williams and VanBlaricom, 1989).

Once an animal has been captured, it may be necessary to retain it for detailed clinical evaluation, intensive treatment, or simply to await the removal of oil from its environment. In the latter instance, it is preferable to assemble holding pens on location for pinnipeds. Such pens must: 1) be designed for quick and easy construction, 2) have the intrinsic strength to contain the animals, and 3) adequately meet the behavioral and physiological needs of the species and age class to be held. Following the sinking of the Sanko Harvest, more than 200 New Zealand fur seal pups were held in five temporary pens constructed on two separate islands. The pens were made from chicken wire and averaged 5 m by 3 m in size, with a fence height of 1.2 m. Shade was provided by tarpaulins. These structures held the animals for up to two and a half days until the oil had been cleaned from the surrounding areas. Overcrowding in one pen led to the death of six pups, but otherwise the pens were adequate (Gales, 1991).

When permanent holding facilities are required (as with polar bears), it may be necessary to transport the animals from the capture site. Such undertakings are logistically challenging, but allow intensive study of the affected animals. A major problem associated with longterm holding of oil-fouled pinnipeds and polar bears is the stress associated with removing an animal from the wild. Even healthy individuals taken into captivity may experience difficulties during acclimation, particularly in learning to accept food. The problems are intensified if the animal is clinically compromised. Furthermore, some species and age groups are more adaptable than others. (See Chapter 1.)

Cleaning Procedures

The selection of appropriate chemicals for cleaning fur or hair is often constrained by logistics, supply, and local availability. The use of Dawn^™ detergent has been recommended for cleaning oiled sea otters (Chapter 6) and is probably appropriate for oiled pinnipeds (Figure 15.1) and polar bears. Another product that has proved effective is CT 18^® concentrated cleansing gel (Chemtech Products, Australia). It is a neutral pH, nonionic detergent with a phosphate buffering system that works well in salt water and causes little irritation to skin and mucous membranes. Furthermore, it is a nonsolvent and biodegradable. Two washes with CT 18^® removed 90% of the oil from fur seal pups, but left a detergent residue even after rinsing. The animals were subsequently sprayed with Preen Trigger Prewash Spray (Samual Taylor, Australia), and this powerful de greaser was massaged into the fur before being rinsed off. Preen^® contains a low odor aliphatic hydrocarbon solvent and less than 20% by weight of a nonionic degradable surfactant (alcohol ethoxylates). Preen^® successfully removed the detergent residue (Gales 1991).

Davis and Anderson (1976) used several detergents on gray seal pups in Wales. They found that Winfield^® detergent liquid and BP 1100X^® were the most effective, although the latter was less effective against weathered oil.

To effectively clean an animal, the detergent must be thoroughly worked into the fur. This can be accomplished using a stiff bristled hair brush for both the washing and rinsing steps. The number of washes and rinses will depend on the effectiveness of the detergent and how much oil is on the animal. Oiled fur seal pups needed three wash-rinse cycles that took approximately thirty minutes per animal (Gales, 1991). A high volume supply of clean water greatly facilitates the cleaning procedure. In the field this can be achieved through the use of high pressure water pumps. Cleaning stations should be situated far enough from the major seal haul out site to minimize disturbance.

The need to dry the animals will depend on the ambient conditions. It is probably less critical to dry pinnipeds than the more thermally sensitive polar bears or sea otters.

Washing animals should only be attempted when the risk of recontamination has been removed or significantly reduced. Clean-up operations may be able to deal with oil on the shore more easily than on nursing mothers, which readily transfer oil to their pups. Davis and Anderson (1976) discontinued their cleaning efforts partly because of maternal recontamination.