ch1 Introduction
Chapter 1 – Introduction
The thermoregulatory and metabolic consequences of external contamination have been well documented for oiled sea otters (Costa and Kooyman, 1982; Williams et al., 1988; Davis et al., 1988). In contrast, there has been little evidence of toxicological effects following crude oil exposure in these marine mammals. Geraci and Williams (1990) reviewed the effects of accidental spills and experimental oiling on sea otters and found little indication of organ damage. In several spills involving wild river otters (Lutra lutra, Lutra canadensis), it was not possible to correlate the cause of death with oil contamination (see Chapter 15).
With so little information about the systemic effects of oil on sea otters, it has been difficult to determine the cause of the high mortality in otters contaminated during the Exxon Valdez oil spill (EVOS). Moreover, the effects of external oiling are not easily distinguishable from the possible toxicological effects of hydrocarbon exposure. The purpose of this chapter is to evaluate the primary factors that may contribute to mortality in oiled sea otters. Specifically, the physical and chemical effects of oil exposure and the stress of capture and rehabilitation are discussed. The conclusions of this chapter are based primarily on data from wild sea otters captured for rehabilitation or found dead on beaches following the EVOS. Clinical evaluations, necropsy results, histopathologic assessments, and tissue residue analyses were used to evaluate the cause of death. Because tissues taken during necropsy are critical for these investigations, we first review the procedures for tissue sample collection and storage, histopathology, and toxicology.
ch1-Prespill Planning
Prespill Planning
In waters under United States jurisdiction, the U.S. Fish and Wildlife Service (USFWS) under the Marine Mammal Protection Act has lead management responsibility for sea otters. In Alaska and Washington State, the capture of oiled sea otters must be conducted or supervised by personnel from the USFWS. In California, the Department of Fish and Game (CDFG) will supervise the capture of oiled sea otters with the USFWS retaining oversight responsibility; both will participate in sea otter captures.
To quickly and efficiently implement a capture operation, prespill planning should include: l) an agency-approved response plan, 2) formation of a task force to review and update response plan strategies, 3) trained capture personnel, 4) identification of capture boats and crews, and 5) assembly of equipment and supplies. Members of the task force should include resource trustees, marine mammal experts, and veterinarians from wildlife rehabilitation programs. The members should be able to meet on a regular basis.
A capture strategy should be prepared for the various geographical regions inhabited by sea otters. It should incorporate information on the seasonal abundance and distribution of sea otters, coastal geography, port and harbor facilities, and seasonal weather and sea conditions. To be most effective, a rescue program should be able to respond within six hours. This is only possible if personnel are trained and the capture boats are under contract before a spill occurs. The success of a rescue and rehabilitation program will depend on capturing oiled sea otters quickly and transporting them to a rehabilitation center, and/or moving uncontaminated sea otters to a protected, clean environment.
ch1-training
Training
Wildlife biologists from the USFWS and the CDFG have extensive experience in capturing and transporting sea otters. Their expertise has been developed through years of sea otter management and research. These experts have obtained an understanding of the sea otter’s biology and ecology, the skills required to effectively conduct capture operations, and the ability to use this knowledge for successful captures. As a result, these resource agency biologists will conduct or supervise sea otter capture and will be responsible for training additional capture personnel.
New personnel should be trained prior to an oil spill through programs approved by the USFWS or the CDFG. A training video, “How to Capture Sea Otters,” has been prepared by the USFWS. Additional training videos concerning sea otter natural history, husbandry, and rehabilitation methods (Table 2.1) are currently available. To maintain proficiency in the capture and handling of sea otters, trained personnel should participate in regular oil spill exercises conducted by USFWS, the oil industry, and wildlife task groups.
Three levels of expertise may be involved in a capture operation: volunteer or amateur participants, technical professionals, and scientific professionals. The volunteer or amateur has no previous training in either oil spill response or in marine mammal biology, capture, handling, or rehabilitation. They should not be directly involved in capture operations. However, they may be assigned to assist specific technical or scientific personnel who will be responsible for their training and supervision.
Technical professionals include vessel operators, marine electricians, marine mechanics, etc. They are responsible for vessel and aircraft operation, safety and navigation, as well as mechanical repairs, net repairs, and maintaining supplies. Animal handling by this group must be supervised by the scientific professionals.
Scientific professionals are those trained in such disciplines as biology, ecology, veterinary medicine, etc. They are responsible for capturing the sea otters and coordinating all record keeping. If proficiency training is necessary, capture personnel should participate in annual government and industry-sponsored oil spill drills involving sea otter capture scenarios.
To prevent injury to personnel and animals, newly trained members of the capture team should be supervised by experienced wildlife biologists. Only experienced professionals should operate boats and aircraft. All personnel should be trained in first aid, water safety, and cardiopulmonary resuscitation through U.S. Coast Guard, and American Red Cross courses. This basic knowledge is mandatory for all sea otter capture personnel.
ch1-safety
Safety
Safety should always be the number one priority when capturing sea otters. Capture operations should never be conducted when weather or sea conditions present a danger to personnel. To prevent injuries, the following regulations should be implemented: U.S. Department of Transportation, U.S. Coast Guard, and state regulations for vessel operation; the U.S. Department of Transportation, Federal Aviation Administration, and state regulations for aircraft safety; the U.S. Department of Labor, Occupational Safety and Health Administration (OSHA), and state regulations for handling hazardous substances.
ch1-OSHA Regulations for Handling Hazardous Substances
OSHA Regulations for Handling Hazardous Substances
Wildlife capture teams may operate in the immediate area of an oil spill and be exposed to fresh crude oil and other chemicals. (See Chapter 14 for a discussion of the properties and potential hazards of petroleum hydrocarbons.) The OSHA requirements for capture teams in the spill area are covered by the “Hazardous Waste Operations and Emergency Response-HAZWOPER” standard (29 CFR 1910.120). In addition to many other requirements, the standard regulates worker safety and health during postemergency response operations. The standard defines postemergency response as “that portion of an emergency response performed after the immediate threat of a release has been stabilized or eliminated, and clean-up of the site has begun.”
The hazards to employees during an oil spill vary widely in terms of the potential severity of injury or illness. For job duties and responsibilities with a low magnitude of risk, such as oiled wildlife capture, fewer than twenty four hours of training may be appropriate. Although the number of hours of training may vary, a minimum of four hours is adequate in most situations. The U.S. Coast Guard and other concerned parties have requested flexibility in the amount of employee training required for petroleum spill clean ups and other types of response operations following emergency situations. The OSHA Regional Response Team representative will determine the acceptable training requirements for various job duties on a case by case basis.
OSHA has not specifically defined the HAZWOPER training requirements for wildlife capture teams, but general requirements should include: 1) initial or refresher training on the hazardous nature of petroleum hydrocarbons and methods to reduce exposure, 2) use of protective clothing and equipment to prevent absorption through the skin, and inhalation or ingestion of petroleum hydrocarbons, 3) medical examinations before and after the capture operation, and 4) regular decontamination of capture equipment and clothing.
ch1-Capture Equipment and Techniques
Capture Equipment and Techniques
Logistical Support
A capture program for sea otters requires specialized equipment (Appendix 6 Download PDF) and personnel knowledgeable about its operation. Key equipment for the logistical support of the program include state-of-the-art communications equipment, capture boats and support vessels, and aircraft.
(a)Communications. Communication between capture teams, transport vessels, and rehabilitation facilities is essential for a successful sea otter rescue program. During a capture operation, the communications equipment aboard each support vessel should provide reliable contact with emergency assistance, the rehabilitation center, other capture vessels, and aircraft. Marine band radios, single side band radios, hand-held radios, and cellular telephones vary in effectiveness, depending on the location of the capture operation, coastal geography, and shore-based relay equipment. Prior knowledge of the available frequencies for radio communications within the home range of sea otters will facilitate communications during a spill.
(b) Capture Boats and Support Vessels. The location of the oil spill will determine the most efficient way to capture sea otters. If the spill is close to a harbor or area with easy boat access, daily excursions with small capture boats are best. For spills not quickly accessible by small boats, the safest and most efficient way to capture sea otters is to deploy larger support vessels (i.e. 40 to 60-foot fishing boats) with one or two skiffs each. The total number of support boats will depend on the size of the spill, the number of otters at risk, and the coastal geography. During the Exxon Valdez oil spill (EVOS), twenty large support vessels were used. Support boats should have 240 square feet of deck space to store 20 large kennel cages, communications equipment compatible with those employed on other capture vessels, and U.S. Coast Guard approved marine safety equipment. If the support boats remain at sea for several days or longer, they should have sleeping accommodations, adequate fresh water and provisions for the crew and capture team, seawater pumping capacity to clean equipment and rinse down otters, and adequate fuel storage. Each boat also should have a freezer that can store 200 lbs of seafood for feeding the otters.
Sea otters should be captured using 18 to 20-foot skiffs. Unless hazardous sea conditions warrant the use of inflatable boats, rigidhull skiffs are recommended because they provide a more stable working platform. When operating without a support vessel, the capture boat should be equipped with a marine radio and directional finder, plus a hand-held radio. In some areas cellular phone service may be available. When the capture boat operates in association with a larger support vessel, a hand-held radio is adequate for communication. For safety, each skiff should have reserve outboard motors and standard marine safety equipment. Outboard motors are less reliable in oil contaminated water because oily debris may be sucked into the water intake/ cooling system. Consequently, we recommend frequent maintenance checks for motors to ensure uninterrupted capture operations.
(c) Aircraft. If the capture operation is more than fifty miles from the rehabilitation center, helicopters and airplanes should be used to transport the sea otters. This will reduce the transport time for the otter, thereby improving the animal’s chances of survival. The support vessels should deliver kennel cages containing the otters to a suitable shore location where they can be transferred to a helicopter or airplane. Ideally, the aircraft should be large enough to carry five or more large kennel cages and an animal care specialist, although smaller aircraft have proven useful.
Capturing Sea Otters
The techniques and equipment for capturing sea otters have been refined in recent relocation programs. Three methods are currently used for the nonlethal capture of adult sea otters: dip net, tangle net, and Wilson trap. The method of choice will depend on location and activity level of the otter, level of expertise of the capture personnel, and ocean conditions. Alternative methods such as deterrents and herding to move sea otters away from a spill site have been attempted with only limited success (Davis et al., 1988a).
(a) Dip Net Technique. This method requires the least amount of specialized equipment. It is best suited for capturing sea otters that have hauled out and young sea otters that are resting or grooming in open water. Adult sea otters that are feeding or otherwise attentive are least likely to be captured with a dip net. The method requires: 1) a maneuverable skiff (generally 18 to 20 feet in length), 2) a stout, long-handled salmon dip net (Figure 2.1), 3) an experienced boat driver, and 4) a strong person to handle the dip net. The person holding the dip net should crouch in the bow of the boat and hold onto a bow rope. The skiff operator approaches the sea otter at high speed and then throttlesback as the person scoops the animal into the net. The netted otter should be held against the side of the boat at the surface of the water until the skiff operator or an assistant can help bring the animal into the boat.
During the capture operation, the sea otter may become aware of the boat’s approach and attempt to escape. Otters that assume a defensive, pawing posture or swim away by backing up on the water’s surface are the easiest to capture. A sea otter that evades the first capture attempt will become wary and more difficult to capture on subsequent attempts. Although oiled sea otters may be lethargic and easier to capture than healthy otters, no more than five attempts should be made to capture an otter. If the animal is vigorous enough to evade easy capture with a dip net, then it probably does not require rehabilitation. The physiological stress experienced by the otter during a prolonged chase may be as harmful as the oil. Thus, the duration of pursuit must be weighed against the following factors: 1) the likelihood of the animal surviving present oiling, 2) the potential for future oiling, 3) the possibility for future capture, and 4) the threat to the animal of continued pursuit. If capture is warranted but the dip net technique is unsuccessful, then other capture methods should be considered.
(b) Tangle Net Technique. This passive method of capture should be used around kelp beds or in areas of predictable or regular sea otter movements. Tangle nets may also be used in open water, especially in areas of predictable otter movements, but are generally less successful. A large number may be captured with time and patience, but this method is the least selective capture technique and requires constant monitoring. The tangle net should be a modified gill net made of 10 inch (23 cm) stretchmesh netting, a foam core float line, a one inch (3 cm) nylon rope serving as a lead line, and a single anchor line (Figure 2.2). Foam core (corkless) float line is preferred over surface cork (peanut) floats, which are often chewed by entangled otters. The nets should be 18 feet (6 m) deep and 100 to 300 feet (33-100 m) long. Equipment and facilities for repairing and cleaning nets will also be needed.
Tangle nets should be deployed with the anchor upcurrent so that the net will be stretched out by the flow of water. Nets are set in open channels or swaths cut within the kelp canopy, around the kelp boundary, or within otters’ routine travel areas. In areas with kelp, the down-current end of the net can be wrapped loosely around kelp fronds and marked with a small buoy to aid in net recovery. Certain oceanographic circumstances may require the placement of anchors on both ends of the net. The nets should have enough scope on the anchor line and a large enough buoy to prevent the anchored end of the net from being pulled underwater by currents or tides.
If a small skiff with a hydraulic net spool is available, the net can be deployed more quickly and efficiently using the Klinkhart/Hecht Method (Figure 2.3). For this method, a site is selected along the shore or near a small island. The anchor line of the tangle net is secured to the shore, and the boat is backed away allowing the net to reel off the spool. The free end of the net is marked with a buoy and dropped into the water. Otters tend to follow the shoreline and become entangled in the net. If the natural movement of otters does not result in a capture, the boat can be used to slowly herd the otters in the direction of the net. This technique is also effective in offshore kelp beds. To recover the net, the process is reversed. The free end of the net is secured to the spool and slowly wound in, drawing the boat toward the shore until the anchor is recovered.
Sea otters can drown once they become entangled. Therefore, tangle nets should be continuously monitored and the entangled otters quickly removed. To avoid disturbing sea otters in the capture area, the nets should be monitored from shore using a spotting scope or binoculars. If it is not possible to quickly retrieve the otters, then tangle nets should not be used. Tangle nets should not be deployed under the following conditions: 1) in shallow water where nets can snag on rocks, 2) in stormy weather and rough sea conditions, 3) in nursery areas with many females and pups, or 4) overnight in areas with abundant sea otters or pinnipeds.
An exception to the last precaution occurs in areas of low sea otter abundance, where the nets may be left overnight. The nets should be checked every two hours during the day, beginning at first light and ending at dusk. Because most sea otters are entangled at night, a capture boat should be used to check the nets early in the morning. If two otters are entangled within reach of each other, they should be removed first to prevent fighting and injuries.
To remove an otter, the net should be pulled across the bow of the boat. The entangled animal is lifted onto the boat and placed into a restraint box (see Figure 3.1). A stuff bag (a nylon duffle bag filled with foam rubber or rags) should be pressed firmly against the otter’s chest while it is untangled or the net is cut away. Care should be taken to avoid injuring the otter or personnel when cutting the net. This physically demanding process requires two experienced people.
Tangle nets need constant maintenance by someone skilled in net repair. Holes should be repaired after each capture. During an oil spill, nets often become contaminated and should be washed with Dawn TM (Proctor & Gamble) dish washing detergent. Nets can be cleaned on board the support vessel by scrubbing portions of the net in a container partially filled with the detergent solution.
(c) Wilson Trap Technique. The diver-operated Wilson trap was developed in California for capturing sea otters (Figure 2.4). It is very effective for capturing a specific animal. The trap consists of a coneshaped, aluminum frame (30-35 inches long, 32 inches in diameter) which supports a net bag. The metal frame is attached to a diver operated underwater propulsion vehicle (UPV). The trap and UPV may be operated by divers using open-circuit, Self Contained Underwater Breathing Apparatus (SCUBA) or closed-circuit SCUBA (rebreathers). The latter is more effective with the Wilson trap, because no air bubbles are produced to alert the otter of a diver’s approach. Personnel with extensive diving experience are mandatory. The divers should have underwater navigation skills, underwater propulsion vehicle experience, and be physically capable of long-distance underwater swims with bulky equipment. Once proficient in these skills, the diver can consider additional training in the use of rebreather equipment. Training in the use of the Wilson trap with rebreathers is available through the USFWS and the CDFG.
The Wilson trap is designed to capture sea otters resting on the water’s surface. Experienced capture teams can often catch more than one otter at a time. The capture team requires a minimum of four people; at least two divers, a dive tender, and a boat operator. Whenever possible, capture teams should be in communication with an on shore observer who monitors the location of the otters. The dive boat should be anchored at least 150 feet downwind of the target animals. In general, the two divers maneuver their UPV and Wilson trap to a position below the target. The UPV is then driven straight up at full speed to trap the otter(s) at the surface. A draw-string is used to close the net bag once an otter is in the trap. Two carbon-dioxide-filled cartridge floats can be attached to the trap to float the captured animal at the surface while the divers await the boat’s arrival.
(d) Deterrents and Herding. Several attempts have been made to control sea otter movements in order to decrease the number of otters contaminated during a spill (Davis et al., 1988a). Unfortunately, no current method consistently deters sea otters from entering an oil spill area. Sea otters will avoid boats and respond to cracker shells, horn blasts and killer whale vocalizations, but the animals rapidly habituate to these stimuli. Despite slight modifications in behavior, the duration of response to deterrents and attractants is inadequate for protecting sea otters from potential contamination during an oil spill.
Handling
Sea otters are highly susceptible to capture-related stress; therefore, handling should be minimized. Health problems may result from capture, handling, transport, and holding of the animals (see Chapter 5). At least one member of the capture team should be experienced in recognizing stress and capture myopathy syndrome, and be able to initiate treatments.
Despite their sensitivity to stress, sea otters have sharp claws and powerful jaws that can inflict serious wounds. Only experienced wildlife biologists should handle sea otters. The following equipment is required for handling these animals: 1) net bags, 2) restraint boxes (see Chapter 3, Figure 3.1), 3) leather gloves, 4) kennel cages, and 5) capture forms.
Also, food and ice should be available for otters awaiting transport. Scales for weighing the animals, equipment for tagging them, and capture forms (Appendix 2, Forms C, D, E Download PDF) should be accessible on the support boat. Daily record keeping is essential; daily journals should include date and time of activities with detailed descriptions of capture locations and methods. A copy of each otter’s capture form should be attached to the kennel cage.
Once an otter has been captured, it should be transferred to a kennel cage as soon as possible. This can take place either aboard the support vessel or on shore. Otters captured with a dip net or a Wilson trap can be placed directly into a kennel cage. An otter captured in a tangle net should be brought aboard the skiff and placed in a restraint box. Restraint boxes come in a variety of sizes and designs, including simple boxes with and without lids, and wedge-shaped boxes. Preferably, restraint boxes should have a sliding lid and a sliding vertical door at one end. (See Chapter 3, Figure 3.1.) Otters placed in restraint boxes are transferred to kennels by placing the sliding door of the box next to the open door of a kennel cage. The sliding vertical door is opened, and the otter walks into the kennel cage.
If the restraint box does not have a sliding door, a small net bag with a drawstring closure is useful for transferring the otter from the box to a kennel cage (Figure 2.5). The net bag is draped over the opening of the box before the otter is released from the capture device. The captured otter is placed directly onto the net which drops into the box. By quickly pulling the draw string the net bag is closed around the otter. The box restricts the movements of the netted otter and facilitates handling for examination or transfer to a kennel cage.
Small, lethargic otters may be moved by picking the animal up by its hind legs. The animal is held upside down, twelve inches or more in front of the handler, with its head facing away from the handler. Because the suspended otter tends to roll forward, its teeth and front paws should remain out of reach of the handler. From this position, the otter can be placed directly into a restraint box or kennel cage.
Each animal is weighed and visually examined before transfer from the net bag or restraint box to the kennel cage. Weight, sex, estimate of age class, state of vitality, and estimated degree of oiling are recorded on the capture data forms. Identification tags should be attached to the hind flippers. This is accomplished by pulling the hind flippers through the sliding, vertical door at the end of the restraint box. (See Chapter 3.)
If a veterinarian or animal care specialist is aboard the support vessel, the otter should be examined for signs of hypothermia, hyperthermia, or other medical problems. If veterinary support is unavailable, biologists should monitor captured otters for significant changes in behavior or health. In particular, body temperature, seizures, and respiratory distress should be recorded on the capture form (Appendix 2, Form C Download PDF). This should accompany information on the capture time, date, location, and the specific information for each animal. One copy of the capture form should remain with the otter, one should be sent to the USFWS, and one should remain on the capture boat.
Sea otters that are heavily or moderately oiled are susceptible to hypothermia and should be placed in sheltered areas on the support vesse1. Seafood should be offered to all of the otters every three hours as they await transport to the rehabilitation center. The time, type of food, and amount eaten should be recorded on the capture form which is sent with the otter to the rehabilitation center.
Transportation
Transportation of the sea otters from the support vessel to the rehabilitation center may occur by boat, aircraft, or truck (Cramer, 1990). The goal is to move the sea otter to the rehabilitation facility as quickly and safely as possible, minimizing the time between capture and treatment. Newly captured sea otters should be taken to a convenient beach or harbor for transfer. If there is a delay in transport, the otters should be placed in a quiet area and monitored regularly for signs of hyperthermia (panting, warm hind flippers) or hypothermia (shivering, cold hind flippers). Access to water and food should be provided. A veterinarian or veterinary technician should advise the capture crews on the triage, standard care, and emergency care needed for otters during the holding period (see Chapter 4). The air temperature of the holding area and in the transport aircraft or vehicle should not exceed 60°F (15°C). Unless an otter shows signs of hypothermia, approximately five pounds of crushed ice should be added to the cage. A water sprayer or hose may also be used to cool healthy otters and prevent further fouling of the fur.
Transport kennels containing otters should be secured to the decks of vessels or the floor of the aircraft. At least one person accompanying the otters should be an animal care specialist.
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ch1-discussion
Discussion
Following an oil spill, the decision to initiate a capture effort for sea otters must not be made lightly. The authorities legally responsible for conserving and protecting sea otters must be contacted. They will determine the best response option. For all oil spills, it is important to emphasize that the primary response option should be to prevent contamination of animals. Spill diversion and skimming techniques should be used to keep oil away from sensitive sea otter habitat – especially kelp beds, rafting areas, and intertidal mussel beds. Response options such as hazing, herding and other deterrent measures, have been unsuccessful for protecting sea otters (Davis et a1., 1988a), but additional research is warranted. If prevention measures fail, it may be necessary to implement a sea otter capture operation.
Factors that should be considered include: 1) influence of environmental, meteorological, and oceanographic conditions, 2) specific characteristics of the spill, such as the type, amount and distribution of oil, and 3) vulnerability of the sea otter population to the spill (Baker et a1., 1981; Siniff et a1., 1982). Local weather and marine conditions will also affect capture efforts and must be factored into any proposed field operation. Areas where effective capture efforts have taken place include embayments, protected waters, and kelp beds during calm weather. Weather and sea conditions must be safe for capture teams and the associated support operations. If safety can not be ensured, then the emphasis for protecting sea otters must be placed on prespill and preventative spill measures.
Once the above factors have been considered and the decision is made to capture sea otters, program effectiveness will depend on the spill size, timeliness of captures, and availability of rehabilitation facilities. During small spills, the most appropriate response may be limited to notifying trained personnel and basic preparation of equipment in case otters become oiled. A capture program may be unnecessary due to adverse environmental factors or movement of oil out of the sea otter area. Large spills may involve enormous numbers of personnel and, undoubtedly, most of the available response resources. In order to initiate the most effective capture effort, the risk of the spill to sea otters must be assessed and reassessed with respect to its size and direction of movement. All decisions to conduct a capture operation must balance the potential threat of the oil to otters and the risks associated with capturing and handling wild animals (Stulken and Kirkpatrick, 1955).
If the probability of sea otter contamination is remote, initial efforts should consist of daily surveys to determine the distribution of sea otters relative to the movement of oil. Selected areas should be surveyed daily for oiled sea otters and evidence of environmental contamination. Throughout the response period, these areas should be monitored for notable changes. Until the threat of oiling is past, any changes in sea otter behavior and significant population shifts with respect to the location of oil should be recorded. Only experienced biologists with knowledge about the natural behavior of sea otters should conduct these surveys.
When otters are in danger of oiling, preemptive captures may be considered. The term preemptive capture refers to the capture of healthy, uncontaminated sea otters preceding the spread of oil into their range. Uncontaminated otters are captured for their protection and placed in holding pens at predetermined sites or relocated to a safe habitat as determined by federal and state authorities. The techniques for conducting a preemptive capture include Wilson traps, dip nets, and entangling nets. Entangling nets are especially useful because they are capable of quickly capturing large numbers of healthy sea otters. Preemptive captures may be limited by weather conditions, inaccessible habitats, or during a catastrophic spill.
It is important to initiate capture operations quickly once oil moves into the sea otter’s habitat and animals become contaminated. Oiled sea otters captured in contaminated areas are designated contaminated captures. Attempts should be made to capture as many oiled animals as possible in order to: 1) remove contaminated animals and carcasses from the environment, 2) obtain immediate medical care for oiled otters, and 3) survey areas that appear to be threatened or heavily affected. Dip nets and entangling nets will generally be used for contaminated captures. Because contaminated areas are not safe for divers, diving operations should be suspended or limited to clean capture areas. Dip net techniques will be most effective in the early phase of a spill when the oil is most toxic. During this period contaminated animals will often be sick, lethargic and may exhibit a variety of unusual behaviors (Davis et al., 1988b). Aberrant behaviors include aggressive grooming by pawing and chewing at the skin, shaking the head violently, and floating low in the water. Otters may also haul out on land, presumably in an effort to reduce heat loss associated with decreased insulation in water (Costa and Kooyman, 1982; Williams et al., 1988). Heavily oiled sea otters will have pelage with a spiked or pointy appearance; they may be less attentive and more sluggish than healthy otters, and therefore, easily captured with dip nets. Moderately to lightly contaminated animals may not demonstrate significant differences in behavior or appearance.
The acute medical problems associated with oil contamination diminish as the more volatile toxic components of the spilled oil evaporate (see Chapter 4). This results in a decreased percentage of moribund animals. As sea otters become more active and more difficult to capture with dip nets, the effort should shift to entangling nets. The size of the spill and the number and distribution of otters still at risk will determine the number of capture teams needed.
Sea otters that do not appear to be oiled or show only a minor amount of oiling are occasionally taken during a capture operation. These captures are termed clean captures to differentiate them from preemptive captures and contaminated captures. This nomenclature facilitates record keeping and allows all animals to be categorized for the natural resource damage assessment process. Veterinarians in the field and at the rehabilitation facility will determine the health status of these animals. Examination results should be reported daily to the field personnel. This information will help capture teams decide the most appropriate capture areas and when to terminate capture operations.
Some animals will not need to be cleaned and may be moved directly to long-term holding facilities or released into suitable habitats. If the local environment is not safe and regulatory authorities permit, the otters may be translocated. If a significant amount of oil remains in or threatens an area, then clean otters may be captured and held until the threat is past. For example, beached oil may become resuspended in the coastal currents with each tidal cycle and poses a continuous threat. Oil that passes by one area can be redirected quickly by changing winds and currents. Thus, local clean areas cannot be considered safe havens. They must be constantly monitored so that capture operations can be initiated if a threatening situation arises. Such situations can occur days or even weeks after the immediate threat appears to have passed. Daily surveys conducted by federal and state resource agency personnel should be adequate for assessing the threat.
When oiled sea otter carcasses are recovered, the specimens must be documented and turned over to the appropriate agency’s law enforcement officers for evidence. The carcasses are retained for possible litigation and federal natural resource damage assessment. Carcasses should be designated as contaminated carcasses. Carcasses appearing unoiled should be retained for necropsy to determine the cause of death. All specimens should be documented and necropsied before they are turned over to law enforcement officers for evidence. Uncontaminated carcasses should be designated as clean carcasses and disposed of under the appropriate federal and state guidelines for marine mammals.
ch1-summary
Summary
The effectiveness of a capture operation depends on prespill planning, quick notification of trained personnel, the ability to rapidly assess the number of otters at risk, and the efficient mobilization of well-equipped response teams. Experience from the EVOS indicates that the first several weeks of a spill pose the greatest risk to sea otters. An immediate response during this critical period will ensure that the capture operation will provide the greatest benefit to the otter population, especially when the threatened population is small or endangered.