Rescue, Rehabilitation, 

and Release of Marine 

Mammals: An Analysis 

of Current Views and Practices 

Proceedings of a Workshop held in 

Des Plaines, Illinois, 3-5 December 199 1 

Edited by 

D. J. St. Aubin 

J. R. Geraci 

V. J. Lounsbury 

University of Guelph 

Guelph, Ontario 

NOAA Technical Memorandum 

NMFS-OPR-8 

July 1996 

U.S . Department of Commerce 

Michael Kantor, Secretary 

National Oceanic and Atmospheric Administration 

D. James Baker, Under Secretary for Oceans and Atmosphere 

National Marine Fisheries Service 

Rolland E. Schmitten, Assistant Administrator for Fisheries 
Contents 

Workshop Summary and Recommendations . David J. St . Aubin. Joseph R . Geraci and Valerie J. Lounsl 

Introduction ................................. 

Summary of Current Practices ...................................... - 

Pinnipeds ................................................ 2 

Manatees ................................................ 4 

Seaotters ............................................... 5 

Cetaceans ............................................... 7 

Ethics. Responsibilities. and Issues .................................. 9 

WhyIntervene? ........................................... 9 

Responsible Intervention .......................................... 10 

Standards of Care ......................................... 11 

Medical Treatment ........................................ 11 

Need for Quarantine ....................................... 11 

Public Health ............................................. 12 

Euthanasia ............................................... 12 

Release ........................................................ 12 

Preparation .............................................. 12 

Monitoring .............................................. 13 

Associated Risks .......................................... 14 

The Regulatory Process ........................................... 15 

Critical Needs and Recommendations ................................ 16 

Acknowledgments ............................................... 18 

Literature Cited ................................................. 19 

Appendix I . Directory of Workshop Participants ....................... 25 

Changing Views of Animals: the Ethical Framework of Rehabilitation 

Programs . Franklin M Loew ..................................... 28 

Literature Cited .................................................. 29 

Rehabilitating Stranded Cetaceans and Pinnipeds: Management Issues 

and Data Summary . Aleta A . Iiohn and Dean M Wilkinson .......... 30 

Applicable Statutes. Regulations. and Policies ......................... 30 

Statutory Requirements ...................................... 30 

Animals on the Beach ...................................... 31 

At the Rehabilitation Facility ................................ 31 

Permanent Retention of Treated Animals ....................... 31 

Releasing Treated Animals .................................. 31 

The Number of Pinnipeds and Cetaceans Released or Retained ............ 32 

Recommendations ............................................... 33 

Acknowledgments ............................................... 34 

Literature Cited ................................................. 34 
WORKSHOP SUMMARY AND RECOMMENDATIONS 

David J. St. Aubin', Joseph R. Geraci and Valerie J. Lounsbury 

University of Guelph 

Guelph, Ontario, Canada N1G 2Wl 

INTRODUCTION 

Stranded marine mammals have long 

attracted public attention. Those that wash up 

dead are, for all their value to science, seldom 

seen by the public as more than curiosities. 

Animals that are sick, injured, orphaned or 

abandoned ignite a different response. Generally, public sentiment supports any effort to 

rescue, treat and return them to sea. 

Institutions displaying marine mammals 

showed an early interest in live-stranded animals 

as a source of specimens -- in 1948, Marine 

Studios in St. Augustine, Florida, rescued ;a 

young short-finned pilot whale (Globicephala 

rnacrorhynchus), the first ever in captivity 

(Kritzler 1952). Eventually, the public as well 

as government agencies looked to these institutions for their recognized expertise in marine 

mammal care and medicine. More recently, 

facilities have been established for the sole 

purpose of rehabilitating marine mammals anti 

preparing them for return to the wild. Four such 

institutions are the Marine Mammal Center 

(Sausalito, CA), the Research Institute for 

Nature Management (Pieterburen, The Nether,- 

lands), the RSPCA, Norfolk Wildlife Hospital 

(Norfolk, United Kingdom) and the Institute for 

Wildlife Biology of Christian-Albrects University (Kiel, Germany). 

In 1977, a workshop convened to examine the nature and occurrence of marine mammal strandings (Geraci and St. Aubin 1979) 

briefly examined the issues surrounding the fate 

of rehabilitated strandlings (Ridgway and 

Prescott 1979). At that time, placing rehabilitated animals in zoos, aquariums and 

research institutions was seen as a way to reduce 

the need to take animals from the wild. It was 

suggested that rehabilitated harbor seals (Phoca 

vitulina), California sea lions (Zalophus 

californianus), and elephant seals (Mirounga 

angustirostris) could within a few years meet 

the entire demand for public display of these 

species. Although space to accommodate rehabilitated animals was not an issue then, participants at the 1977 workshop recognized the 

eventual need for a sound release program. 

Ten years later a second workshop 

reviewed the history and achievements of the 

national stranding plan in the US (Reynolds and 

Ode11 1991). Regional networks had become 

better organized, more extensive, and capable of 

more effective rescue operations. The result 

was improved success in rehabilitating manatees 

(Trichechus manatus), sea otters (Enhydra 

lutris), and, particularly, pinnipeds. In 1987, 

many rehabilitated harbor seals and California 

sea lions were still being placed in domestic and 

foreign facilities (Hohn and Wilkinson, this 

report). At the same time, the number of animals released exceeded that being retained, as a 

consequence both of improved treatment programs and decreased demand for the more 

common species. 

The trend continued, and by 1991 few 

opportunities remained for placing animals in 

permanent care; virtually all rehabilitated 

pinnipeds were being released (Hohn and 

Wilkinson, this report). Continued growth and 

efficiency of stranding networks, combined with 

limited space, lead to concern that crowding in 

some cases might lower standards of care and 
medicine. Other issues had also emerged. 

Some marine mammal populations had grown 

significantly under legal protection (Mansfield 

and Beck 1977, Le Boeuf and Bonnell 1980, 

Bonnell et al. 1983, Le Boeuf et al. 1983, Reilly 

1984, Zwanenburg et al. 1985, Early and 

McKenzie 199 1, Sergeant 199 1, Siniff and Ralls 

199 1, Woodhouse 199 l), calling into question 

the advisability of releasing animals into conditions where resources might be limited. Devastating morbillivirus epizootics in pinnipeds 

(Heide-Jorgensen et al. 1992) and cetaceans 

(Domingo et al. 1990), although unrelated to 

reintroductions, magnified concern that released 

animals might carry with them pathogens that 

could threaten the health of wild populations. 

Government agencies and stranding networks 

called for a re-examination of the practices and 

policies governing the approach to live-stranded 

marine mammals. 

A workshop sponsored by the Marine 

Mammal Commission and the National Marine 

Fisheries Service (NMFS) was convened in Des 

Plaines, IL, on December 3-5, 1991, to address 

these issues. The forty-nine participants (Appendix I) represented US federal and state 

agencies with jurisdiction over marine mammals, and stranding centers and programs from 

Australia, Canada, Germany, Great Britain, The 

Netherlands, and the United States. Non-marine 

mammal biologists and veterinarians were 

invited to broaden the perspective. To seed the 

discussion, six invited speakers, including one 

who focused on regional and sociological differences in attitudes toward animals, addressed 

various elements of wildlife rehabilitation and 

reintroduction. Their papers are contained 

within this report. Participants with specific 

experience with each of the major groups of 

marine mammals -- cetaceans, phocids, otariids 

(including walruses), sea otters and manatees -- 

were organized into panels to discuss questions 

regarding biological, ethical, medical, and 

practical considerations of rescue, care, euthanasia and release. Panel moderators reported back 

to the assembled group, allowing further discussion on particularly controversial issues. What 

follows here is a summary of current practices 

as reported by each group, and a synthesis of 

opinions on larger questions, including: Do we 

invariably act in the best interest of the animal? 

Is it humane to rehabilitate an animal that is 

unreleasable and cannot be accommodated for 

long-term care? Are the standards of care 

suitable? Can we judge the fitness of an animal 

well enough to know that it will not again become helpless in the wild? Are precautions 

adequate to protect the wild population from 

introduction of exotic disease? 

No attempt is made to report all the 

opinions expressed, nor to establish how many 

participants favored one view or another. Our 

objective is to present the scope of the discussions, identify consensus when it occurred, and 

highlight opposing views. Recommendations 

presented at the end of the report include those 

introduced during Workshop discussions as well 

as some drawn from subsequent analysis of 

panel reports and written responses to questionnaires provided to each of the participants. 

SUMMARY OF CURRENT PRACTICES 

Pinnipeds 

The vast majority of strandlings in the 

United States are pinnipeds, particularly in the 

northeast and southwest regions (Hohn and 

Wilkinson, this report). Each year, several 

hundred animals are rescued and a high percentage of these are eventually released. The most 

common are California sea lions, northern 

elephant seals and harbor seals. These are 

species that have large, stable or expanding 

populations that do not benefit from rehabilitation programs but for which the majority of 

effort and funding is expended. Hawaiian 

(Monachus schauinslandi) and Mediterranean 

(M monachus) monk seals, on the other hand, 

are endangered, and rescue and release operations are important elements in government- 
sponsored species recovery plans (Gilmartin 

1983, Reijnders 1984, Gilmartin 1990). 

Workshop participants reflected both 

personal opinion and regional policy on whether 

intervening to help a stranded animal is necessary or even appropriate. Regional policy is 

influenced by the density of human populatior~, 

public opinion, character of the shoreline, logistics, and cause of the stranding. In sparse1:y 

populated or remote areas, such as the Pacific 

Northwest and Alaska, most stranded pinnipeds 

are likely to die undiscovered or be intentionalby 

left to their own fate. The same policy of noninterference does not operate in densely populated 

areas, where there is increased public demand 

for action as well as a greater imperative to 

reduce public health risks and protect 

strandlings from possible harassment. Pinnipeds 

that are victims of oil spills or entangled in 

marine debris receive special consideration, 

regardless of where they strand. 

Pinniped strandings generally occur in 

predictable waves, with most coming ashore a:s 

pups during the critical time when they are first 

on their own (Geraci and Lounsbury 1993). 

During peak periods, facilities become crowded, 

quarantine measures are harder to maintain, and 

staff are overextended; these situations make it 

difficult to provide good quality care and medicine. The strain on the system may force a shift 

in practice toward euthanizing more animals, 

but there seemed, among some of the participants, a greater tendency to relax guidelines foir 

release. Because no uniform criteria for release 

have been established, either option is currently 

possible. Strandlings of less common species 

tend to be given special consideration regardless 

of the strain on the facility. Participants stressecl 

that improved educational programs to discourage the public from mistakenly picking up 

healthy pups could significantly reduce demands 

on some facilities during peak periods. 

Compared with other marine mammals., 

the cost and logistics of rehabilitating an indi-. 

vidual pinniped are quite reasonable. They do 

well with modest accommodations, are rather 

resilient, and may come ashore needing only 

nourishment. Quarantine measures are usually 

taken to prevent exposure to disease during the 

rehabilitation period, and the majority of animals are released within a few months. Blood 

and fecal analyses are widely used to assess the 

health of strandlings. Criteria for determining 

whether an animal is suitable for release generally include a normal blood profile, sound 

nutritional state, and independence from medical 

and pharmaceutical support. 

Of all the marine mammals, pinnipeds 

have generated the most concern and controversy over transmission of diseases once they 

are released. Discussion focused on serological 

testing for antibodies to morbillivirus, and 

whether animals with positive titers were considered releasable. [Five months later, NMFS 

instituted a policy requiring that seals with 

positive titers be retained. This was the first 

time that the agency made such a decision based 

on medical criteria.] California sea lions are 

also routinely screened for Leptospira, but the 

releasability of infected animals remained an 

unresolved issue, prompting a recommendation 

for more studies on endemic diseases. Everyone 

agreed that screening for potential pathogens 

should be expanded to better protect wild populations from introduced disease. 

Pre-release behavioral conditioning for 

pinnipeds is minimal, generally limited to reducing dependence on humans, while encouraging 

normal foraging activities and allowing social 

interactions. Otariids are naturally more gregarious, and thus a greater emphasis is placed on 

socialization to facilitate their return into wild 

populations. Except for timing with the natural 

cycle of the species, the release itself usually 

involves little more than opening a cage on a 

nearby shore. This is fortunate because the 

numbers of animals involved in rehabilitation 

programs would make more complicated efforts 

practically impossible. Evidence suggests that 

animals held for a year or more do not adjust 
well in the wild (Harvey 1991) and may need 

more extensive preconditioning. Animals in 

which human-dependence cannot be extinguished -- those that continue to seek and interact with humans after release -- are usually 

candidates for permanent care. 

Unreleasable pinnipeds are a growing 

problem because public display institutions are 

unwilling or unable to accept any more animals, 

particularly harbor seals and California sea 

lions. A number of participants were concernt:d 

that overburdened facilities may tend to release 

animals in marginal health. Others reported that 

some pinnipeds have been held in temporaiy 

quarters not governed by Animal and Plant 

Health Inspection Service (APHIS, US Department of Agriculture) standards for years while 

waiting for suitable placement. The option of 

euthanising unreleasable animals becomes more 

difficult with time in captivity and is generally 

considered inappropriate on the basis of 

unreleasability alone. Participants from A1ask.a 

warned that a problem might develop in accommodating orphaned walrus calves since the 

current policy is to retain them all in permanent 

care. It was recommended that the US Fish and 

Wildlife Service develop a protocol to deal with 

the inevitable surplus. 

Seals from northern Canada are stranding 

farther from their home ranges with increasing 

frequency, particularly along the US Atlantic 

coast (Early and McKenzie 199 1, Ode11 199 1 ). 

Frustration was expressed over the difficulties in 

returning them to their native habitat because of 

the cost, the red tape in dealing with several 

agencies in more than one government, and the 

possibility of transferring disease across a 

national border. Participants working with these 

animals urged that governments help clear a 

path for expeditious return, or assist with permzinent placement of extralimital strandling:;. 

Meanwhile, operators of rehabilitation programs 

must be prepared for long-term care of these 

animals. 

Although many pinnipeds are rehabilitated and released each year, few are monitored 

after release. In the US, NMFS requires that all 

released animals be marked or tagged so that 

they can be identified if they restrand. Because 

of the cost, there is no requirement for tagging 

with either VKF or satellite-linked radio tags. 

Hence, only opportullistic observations of 

tagged animals are possible, and no conclusions 

on survival rates can be drawn. The scientific 

literature contains only sparse data from sightings and restrandings (Seagars 1988, Harvey 

199 1, Reijnders, this report). Participants 

recognized the need for long-term monitoring, 

perhaps on selected indicator species, and urged 

that funds be made available for this purpose. 

Manatees 

In the US, the endangered West Indian 

manatee draws the full attention of a network of 

marine mammal facilities and federal and state 

agencies operating under the same permit authority (US Fish and Wildlife Service 1989). 

The manatee recovery team in Florida has, over 

the years, worked intensively to develop a 

conservation program, which includes rescue 

and rehabilitation. Most participants in the 

manatee panel, as members of the recovery 

team, had met several weeks earlier to discuss 

the same issues considered at the Workshop, and 

their views reflected a previously established 

consensus. 

There is no debate about whether or not to 

rescue a sick or injured manatee. The fact that 

the preponderance of injuries are human-related 

is further justification to intervene. Yet it is 

clear that rehabilitation efforts alone will not 

reverse the impact of damaging encounters with 

boats or the destruction of habitat. Members of 

the panel agreed that rehabilitation efforts must 

operate hand-in-hand with public education, 

tougher enforcement of pleasure craft speed 

limits, and habitat conservation. 
Virtually every live manatee brought to a rel'la- herbivores, they require no predatory skills. The 

bilitation facility is treated until it recovers or main concern is that their already trusting bedies. No effort is spared to restore the animal to havior may be heightened during rehabilitation, 

health, irrespective of space or iinancial limita- placing them at greater risk of injury after 

tions. Consequently, few are eluthanized. The release. 

panel expressed its concern thai existing faciilities may not be able to cope with a rescue operation to save several dozen manatees, for exalmple, in the event of a power plant shut-down in 

winter. [An emergency contingency plan is 

currently in preparation by the US Fish and 

Wildlife Service. '1 

New arrivals are quarantined for up to 

30 days. Manatees with traumatic injuries are 

less stringently segregated thln those with 

clinical evidence of disease. Alier quarantine, 

orphans or abandoned calves are sometimes 

placed with long-term captive females to assist 

them through rehabilitation. There are no specific regulations that govern qu5rantine; faci lities have defined their own criteria, and in most 

cases, standards are considered satisfactory. 

The panel nevertheless reconmended that 

uniform guidelines be established. 

A full range of diagnostic: tools, including hematology, blood chemistry, immunolog:y, 

cytology and bacteriology, is employed during 

the initial medical examination arid was considered acceptable by the panel. At the time of the 

Workshop, there was no known pathogen associated with widespread disease in this species. 

Nevertheless, the panel urged continued precautions against releasing manatees that might 

introduce such pathogens. [Recec tly, antibodies 

to morbillivirus have been detected in Florida 

manatees 3, though there is no evidence that the 

virus causes clinical infection.] 

An effort is made to limit the amount c~f 

time that a manatee is held in captivity. Those 

judged by medical and behavioral criteria to 

have a reasonable chance of surviving are released as soon as possible. The young arle 

generally kept until they reach sexual maturity 

at about five years of age. Pre-release conditioning for manatees is not complicated. As 

Manatees judged to be in good health 

are usually released in spring or early summer 

so they can have the longest period possible to 

acclimate before the onset of stressful winter 

conditions. The panel agreed that manatees 

should be released at a place and time that 

would allow them to resume synchronous movements with conspecifics. Mixing Gulf of Mexico and Atlantic "stocks" is avoided. All animals are freeze-branded prior to release, and 

depending on funding, some are equipped with 

VHF or satellite transmitters. From release 

studies, it appears that most manatees survive 

the critical first winter back in the wild 4. 

The public must be reminded that protective measures are more effective than rescue 

and rehabilitation. The manatee rehabilitation 

program costs roughly $600,000 per year, or 

approximately $40,000 for each animal treated, 

Sea Otters 

The status of sea otter populations 

ranges from threatened in California, to small 

but growing in Washington and British Columbia, to large and expanding in Alaska. Consequently, the level of effort directed toward 

rehabilitation varies according to the perceived 

needs of the population. The threatened status 

of the California population has demanded the 

development of effective rescue and 

rehabilitation programs. There, sea otters observed on land for more than 24 hours are captured and taken to rehabilitation facilities. This 

typically involves some 4 or 5 pups and perhaps 

10 adults each year. In Alaska, sick or injured 

sea otters usually die, in part because the remote 

coastline and sparse population make detection 
and response much more difficult. In the average year, only 1 or 2 animals may reach care 

facilities. 

Existing facilities can comfortably 

accommodate the number of anim 21s collected 

in a typical year. The exception, of'course, was 

the massive response following the ;grounding of 

the Exvon Valdez, which required the construction of three new care centers (Williams and 

Davis 1990). Still, lack of space required that 

some animals be euthanized, a practice normally 

reserved for cases of serious injury. Panel 

members stressed the need for contingency 

plans and training programs in California to 

ensure treatment capability in the event of 

similar disasters there. They cautioned that 

implementation of such plans must carefully 

weigh the benefits of "rescuing" unoiled or 

lightly oiled otters against the risks associated 

with capture, transport, handling and confinement. 

Rehabilitating sea otters i5; costly and 

challenging; the animals have a spec:ialized diet, 

high metabolic rate, and a tendency toward 

stress and thermal imbalance. l'heir social 

needs must also be met, and this may be a 

reason to limit the time spent in isolation. Pups 

are especially demanding and may need several 

months of constant attention, including formulafeeding and careful management of 1 heir pelage. 

In California, each sea otter pup took: on average 

eight months to rehabilitate, at a cost of about 

$20,000. Because of construction expenses and 

location, the cost of treating oilecl sea otters 

following the Exxon Valdez inciderit was more 

than $80,000 per animal (Estes 1991). 

Most rehabilitated adults are released, 

some within days of rescue. Many pups, however, never meet the established release criteria 

either because they remain weak or become too 

dependent on humans. The panel considered 

any sea otter kept longer than two years to be 

unreleasable. Presently, there are emugh facilities to accommodate such animals. However, 

the panel felt that the situation may soon change 

because the number of sea otters in captivity is 

increasing and captive breeding programs are 

being developed. Rehabilitation centers were 

urged to emphasize programs aimed at conditioning pups for successful release. Panel members agreed that obligatory release of all animals 

was unacceptable, and that there would always 

be the need to evaluate animals on a case-bycase basis. 

Prior to release, otters are given a routine health examination, including blood analysis and screening for herpes virus infection. The 

animals must also demonstrate normal behavioral profiles, particularly with respect to foraging and grooming, before being returned to the 

wild. Release usually takes place in an area 

occupied by animals of the same sex and similar 

age (Garshelis and Garshelis 1984, Jameson 

1989). In California, animals captured in extralimital areas are released within the population's 

natural range. 

All sea otters are tagged on the flipper 

before release. Intra-peritoneal radio transmitters that allow long-term monitoring (up to 2 

years) have also proved successful and have 

been recommended for use whenever possible 

(Siniff and Ralls 1988). Survival of released 

otters is unpredictable, and their strong homing 

behavior may result in animals returning to the 

release site. Experimental translocation of 

apparently healthy individuals has met with 

mixed success (Jameson et al. -1982, liathbun et 

al. 1990); animals graduating from a rigorous 

rehabilitation program cannot be expected to 

fare any better. Survival of otters released after 

the Exxon Vnldez spill was poor, perhaps because of re-exposure to oil rather than to any 

particular deficiency in the rehabilitation effort 

(Estes 1991). The panel agreed that. more detailed monitoring studies using implanted radio 

transmitters are needed to determine the effectiveness of rehabilitation programs. 
Cetaceans 

Cetacean strandings, even in remote 

areas, evoke great public reaction (Schefifer 

1989). The level of interest seems to be directed 

to these animals as a grozlp, irrespective of 

whether their population is endangered, threatened or abundant. The primary determinants of 

whether a strandling is immediaitely returned to 

sea, euthanized, or taken for rel~abilitation are 

the animal's size and health, the stranding location, logistic capabilities for moving and transport, and the availability of a suitable care 

facility. 

Strandlings in remote areas are rarely 

found alive, and if they are they are difficult to 

rescue. Large cetaceans, such as sperm or 

baleen whales, are generally beyond help unless 

they simply need to be herded or towed into 

deeper water. Singly stranded animals tend to 

be sick or debilitated and often die before or 

shortly after discovery (Geraci and St. Aubin 

1979). Even healthy animals may succumb to 

the stress of stranding in a matter of hours. Of 

the cetaceans that come ashore alive, relatively 

few reach rehabilitation centers. 

The fate of a stranded cetacean is usually determined after consultation among veteriinarians, representatives from rehabilitation 

facilities, and the regional stranding network 

coordinator. Small animals (i.e., independent 

juveniles or young adults) are easily transported 

and handled and are generally better choices for 

rehabilitation. Success rates for dependent 

calves are steadily improving. Mass strandingis 

are a problem, as few facilities have the resources or budget required to deal with more 

than a single animal or two. Hence, most of the - 

action must be taken on the beach -- either for 

immediate release or euthanasia. 'ne confusion 

and urgency that so often accompany these 

events can complicate matters, and public pressure may sway the decision to retain or release 

an animal that should, perhaps, be euthanized. 

Panel members suggested that more explicit 

criteria for assessing health, including speciesrelated information (e.g., cannot withstand long 

transport, easily stressed) would aid in this 

decision-making process. The panel also endorsed the mandatory involvement of a veterinarian in medical decisions, particularly those 

entailing euthanasia. It also recommended that 

all commitments for long-term care be confirmed before any animal is taken for rehabilitation. In the case of endangered baleen whales, 

where survival of an individual may benefit the 

population, every effort should be made to 

return the strandlings to sea. 

Euthanasia of stranded cetaceans is 

considered appropriate when animals are judged 

to be suffering and there is no hope for survival. 

Methods of euthanizing small cetaceans (reviewed by .Geraci and Lounsbury 1993) were 

considered effective, safe and humane when 

practiced by a qualified person, but participants 

expressed the need for better techniques for 

dealing with large whales. They further noted 

that the improving success in raising orphaned 

dependent young argues against a policy to 

euthanize otherwise healthy calves. 

Historically, the prognosis for rehabilitating a stranded cetacean has been poor. Until 

recently, few ever achieved the level of fitness 

necessary for surviving in the wild, and so they 

were retained for long-term care. Recent advances in husbandry and medicine have improved an animal's prospects for survival after 

release, but the rehabilitation process is longer, 

more labor-intensive, and costlier than for other 

marine mammals. This limits the number of 

centers able to take cetaceans. Those that do 

may be pressured to take additional animals 

even when resources are inadequate. 

Criteria for release include good health 

and nutritional status, normal behavior, and 

normal blood profiles, but as yet do not include 

requirements for serological tests. The risk of 

introduced disease was a concern in light of a 

recent morbillivirus epizootic in striped dolphins 

(Stenella coeruleoalba) (Domingo et al. 1990). 

[Subsequent studies have established the wide- 
spread occurrence of morbillivir~~s in a number 

of cetacean species in the North Atlantic (-. 

Iluignan et ul., 1995 a, b)]. The panel stressed 

the need for more information on disease in wild 

populations. It recommended in~munological 

screening, particularly for morbilli rrirus, herpes, 

hepatitis, and parvovirus, and cor sideration of 

the results of these tests among the criteria for 

judging releasability. 

Present knowledge was considered 

insufficient to establish release critsria based on 

such factors as age at time of stranding, duration 

of captivity, age at release, and social organization of the species. Mandatory re ease of cetaceans was considered unreasonable and unacceptable. Some individuals simplj. do not meet 

criteria that will assure their o,Nn survival; 

others may place the population at risk. 

Preconditioning a rehabilihted cetacean 

for release demands time and ressurces. The 

animal may require several week: of acclimation in a sea pen, a program to diminish reliance 

on humans, adaptation to live prey, and ongoing 

medical and behavioral evaluation. This process 

can be expected to be significantl:! more complex for animals in long-term care or captivity. 

Animals should be releasec within their 

home range, although for some species this can 

be difficult to determine. This may require 

transporting pelagic animals some c istance from 

shore to locate herds of the same s 3ecies, making the release more challenging. I I addition, it 

increases the cost. Participants e: timated that 

the effort involved in rehabilitating jolphins that 

can be released inshore may cost $43-50,000 per 

animal; up to $100,000 may be required for a 

cetacean needing lengthy rehabilitation and 

more elaborate support for release. As an added 

note, in 1992, the US Navy held a workshop to 

discuss reintroduction as an option Ior cetaceans 

in their care (Brill and Fried1 1993) A panel of 

biologists, trainers and conservationists concluded that 7-1 1 years of prepara ion may be 

necessary to condition long-term captives and 

captive-born animals for release and to develop 

appropriate monitoring equipment and followup programs. The calculated costs involved in 

such reintroduction efforts were judged to 

greatly exceed the expense of providing for the 

animals in their current environment. 

Compared with other marine mammals, 

few rehabilitated cetaceans have been released, 

and even fewer have been tracked or monitored 

(Bruni et a/. 1990, Kastelein et a/. 1990). In 

1987, three stranded long-finned pilot whales 

(Globicephala melas) that had been rehabilitated 

at the New England Aquarium were released in 

the vicinity of a wild pod offshore. One of the 

whales was equipped with an Argos satellitelinked transmitter and successfully tracked for 

95 days. Data derived fkom satellite readings on 

dive time, movements, location and swimming 

speed indicated that the whale's activities were 

normal for this species (Mate 1989). Subsequent attempts to track released cetaceans have 

been less successful. ,4n Atlantic white-sided 

dolphin (Lagenorhynchus acutus) (Mate et a/. 

1994), two long-finned pilot whales ', and a 

young female Bryde's whale (Bulaenoptera 

edeni) (Walsh et al. 193 1) were tracked for 4, 8, 

and 10 days, respectively, before the signals 

were lost. One short-finned pilot whale, released in 1991, was sighted 3 years later within 

a large pod of short-finned pilot whales 6. 

Clearly, more information on post-release 

behavior and survival is needed to develop 

meaningful release criteria. 

Although the Workshop's principal 

focus was the reintroduction of rehabilitated 

stranded cetaceans, the panel also reviewed the 

mixed results of the few instances in which 

long-term captive and captive-bred cetaceans 

have been released. Preparations then in progress to release long-term captive dolphins from 

an Australian facility7 were ultimately disappointing, despite careful planning and thorough 

preconditioning (Waples and Gales 1993). Of 

the 9 animals released, five were thought to 

have acclimated successfully, one calf was 

presumed to have died., and three were recap- 
tured for permanent holding after unsuccessful 

foraging resulted in significant weight loss. 

Apparently healthy animals, captured for study 

and later released, have met with better success. 

A gray whale calf taken from Scammon's Lagoon in 1971 and raised at Sea World in San 

Diego for one year was radio.tracked for 2 

months after release into a small group of migrating whales, suggesting that he animal had 

readapted successfully (Evans 1974). Two 

young male bottlenose dolphins (Tursiops 

truncatus) captured in Florida, held for two 

years and released back into their home range in 

October 1990, readapted quickly (Wells 1989, 

Bassos et al. 1991) and were still being monitored at the time of this Workshop, over one 

year later. 

The current policy is to visually mark or 

tag all released cetaceans, though participants 

recommended the additional use of radio transmitters (VHF for coastal species and satellitelinked for pelagic forms) whenzver possible. 

The need for more extensive mmitoring programs was emphasized, in view of the limited 

information available and the controversy surrounding cetacean release programs (Advisory 

Committee on Marine Mammals 1992). Federal 

~;ponsorship would be needed to underwrite the 

costs of monitoring, which shoulcl be continued 

for a minimum of one to two months after 

release. Yet such sponsorship is unlikely unless 

Ithe release involved an endangered species or 

was part of a comprehensive prog,ram designed 

1.0 test rehabilitation success. 

ETHICS, RESPONSIBILCTIES, 

AND ISSUES 

Against the backdrop of current practices, participants explored the ethlcal, legal and 

practical context in which rescue, iaehabilitation, 

and release programs operate. Rt gional and 

international differences in approach and philosophy were apparent in debates, making it clear 

that many issues are not likely to be resolved to 

the satisfaction of everyone with an interest in 

rehabilitation programs. 

Much of the following discussion applies broadly to all marine mammal groups, with 

some distinctions made for endangered and 

abundant species. Principal topics considered 

include the motives underlying intervention, the 

obligations involved in caring for the animals 

after they are rescued, and the responsibilities 

associated with returning the animals to the 

wild. 

Whv Intervene? 

Programs to rescue and rehabilitate sick 

and injured animals are founded on two general 

principles -- altruistic assistance to the sick or 

injured, and conservation of wild populations. 

In the process we gain scientific and medical 

knowledge, though this benefit is rarely proposed as a principal objective. Conservation is 

a realistic motive for reintroduction programs 

benefiting threatened terrestrial species such as 

the golden lion tamarin (Leontopithecus rosalia) 

(Montali and Bush, this report), and this may 

apply to some marine mammals as well. Endangered monk seals in Hawaii and the Mediterranean (Gilmartin 1983, Gilmartin 1990, Reijnders et al., this report), manatee:; in Florida 

(US Fish and Wildlife Service 1989), and sea 

otters in California may be benefiting from 

reintroduction of even a few to the wild. At the 

present rate of their decline, northern fur seals 

(Callorhinus ursinus) and Steller sea lions 

(Eumetopias jubatus) may soon require similar 

assistance (York 1987, Cranmore 1990, 

Loughlin et al. 1992, Marine Mammal Commission 1993). [Since the Workshop, the northern 

fur seal population appears to have stabilized.] 
For robust populations, conservation is 

not a defensible argument for rehabilitating 

animals; participants were in agreement on this 

point. In the years since marine lr~ammals in the 

United States and Canada haw been placed 

under legal protection, several ~~opulations of 

pinnipeds -- California sea lions, gray seals 

1(Halichoerus grypus), harp seals (Phoca 

,poenlandica) -- have grown sut stantially (Le 

IBoeuf and Bonnell 1980, Le Boellf et al. 1983, 

Zwanenburg et al. 1985, Sergeant 199 1). Reintroducing a few or even a few huridred of these 

animals will be of little benefit tcl most stocks, 

and of less benefit to the overall F opulation. 

Yet, because they are so rlumerous and 

accessible, these animals contribute to the 

developing reservoir of information on care and 

rj~ledicine that can be applied to sp1:cies needing 

help. Through strandings we have learned about 

diseases and other causes of nat~ral mortality 

(~Gilmartin et al. 1976, Domingo et al. 1990, 

Kennedy 1990), and have gained insights into 

physiology, metabolism (Walsh et 21. 1991) and 

aspects of life history and behavior that help 

determine when and where a strar dling can be 

rehabilitated and reintroduced with a reasonable 

chance of survival (Geraci and Lounsbury 

1993). A stranding may be the first lead to an 

unusual mortality event (Geraci et al. 1989, 

O'Shea et al. 1991), alerting those monitoring 

marine mammals and their environment. 

Stranding rates can provide a rough index of 

abundance. As top-level predators, marine 

mammals accumulate contaminants and thereby 

provide clues to the health of their habitat (- 

Reijnders 1980, Addison 1989, Muir et al. 

1990). But this kind of information valuable as 

it is to science, is not likely to sustain the energy 

and popularity of rescue and rvhabilitation 

programs. 

The motive behind most suzh efforts is 

humane concern for an animal in distress. Loew 

(this report) has described how dzmographic 

changes in the United States and, by inference, 

other developed nations, are intertwined with 

evolving perceptions of animals and nature. The 

ethical operative is that humans do not ignore 

suffering in wildlife, and help whenever they 

can. At no time is the obligation to intervene 

felt more than when a strandling is a victim of 

our own activities (e.g., gun shot wounding, 

entanglement in fishing gear, fouling with oil). 

Marine mammal display and rehabilitation 

centers have been instrumental in bringing this 

plea for empathy to the public. 

Antithetical to this view was one, perhaps more widely held than expres;sed in the 

Workshop's public forum, that rescue programs 

in some cases interfere with natural selection 

and population regulation. Intervention should 

therefore be limited to euthanizing ailing animals, with rescue efforts directed only toward 

enhancing the survival and recovery of threatened or endangered species. Such practice is 

endorsed by some biologists and employed as 

policy in at least one European country. The 

general public in most regions of North America 

would likely oppose widespread implementation 

of such a policy. 

RESPONSIBLE INTERVENTION 

Those assisting a strandling assume 

responsibilities to the animal, its parent population, the public, and the government agencies 

sanctioning the actions of the rescue operation. 

The animal may require expensive medical care 

and housing, and careful monitoring to assure 

survival after its return to the wild. The population as a whole must be protected ifrom any 

introduced disease, disruption of the social 

order, or perhaps burdensome addit~~ons toa 

habitat already at or beyond carrying capacity. 

Rehabilitation centers must balance biologically 

and medically sound programs with sometimes 

conflicting directives from regulatory agencies 

responsible for the welfare of the population at 

large and from public supporters that may 

encourage the return of all rescued animals. 
Standards of Care Need for Ouarantine 

The United States Dep irtment of Agriculture has established minimilm standards of 

marine mammal care (APHIS 1993) which 

govern the physical environmer t and husbandry 

practices of any display and rzsearch facility. 

APHIS regulations do not apply to stranding 

quarters at these institutions or at all to thost: 

dedicated entirely to stranding!;. The rationale 

has been that a sub-standard lacility is better 

than no facility at all. Worksl~op participants 

expressed the view that this approach was 

unacceptable. There was a call for enforceable 

minimum standards (see Critkal Needs and 

Recommendatio~zs), with recog lition that these 

requirements might be less than those for public: 

display and research facilities, and that some 

operations, unable to bear increased costs of 

meeting even these standards, might be forced to 

close. 

Medical Treatment 

Rehabilitation centers are essentially 

hospital operations with veterinary supervision. 

Newly admitted animals require a thorough 

examination, which veterinaria~~s attending the 

Workshop agreed should enconlpass: assessing 

the animal's behavior (e.g., responsive, comatose, convulsing), physical condition (e.g., 

injuries and deformities) and kital signs (e.g., 

body temperature, heart and respiratory rates), 

and blood, parasitological, micr3biological and 

treatment. At one end of the spectrum are those 

who balance the animal's condition with its 

prospects for release, long-term care and available space. At the other are th Ise who accept 

any animal that has a reasonable chance of 

recovering from its ailments, and defer other 

considerations. There was cclncern that the 

latter approach can quickly ou'strip a center's 

ability to provide full medical attention when 

dealing with a large number of ilnimals. 

Stranded marine mammals, even those 

without clinical evidence of disea~se, can carry 

pathogens that may be transmitted to others in a 

rehabilitation facility or permanent colony. 

New arrivals that are ill may themselves be 

more susceptible to infections from resident 

animals. Strandlings should therefore be isolated until appropriate diagnostic tests are performed and treatment instituted. Done well, 

isolation involves a discrete water supply, 

separate area for food preparation, strict disinfection procedures, no access by the public, pets 

or other domestic animals, and separate protective clothing, or better still, a separate staff. 

It was pointed out that meeting this 

objective is costly and difficult, but should be 

considered essential and incorporated into the 

design of the facility. Some facilities use recirculating water in a closed system, others have 

several pools in a common filtration system, or 

contiguous pens and no control over air movement. Under trying circumstances, some centers 

attempt reasonable quarantine measures; others 

improvise as they can. Where no quarantine 

exists, it is possible for a strandling to arrive at 

a busy facility more or less free of disease, and 

become infected with a serious paihogen hours 

before release. 

Quarantine space can be quickly overtaxed by a sudden influx of animals, rendering 

the system ineffective when it is rnost needed. 

One alternative solution has been r:o isolate the 

entire rehabilitation colony for a ti,me. But this 

step requires a schedule under which each 

animal is eventually released from quarantine 

conditions. Lack of agreement on the criteria 

for removal of quarantine has led, in the experience of one participant ', to instances in which 

animals have been isolated for weeks or months 

after the point when they no longer represent a 

threat to the health of other individuals. 
- P~rblic Health or forces a change in criteria for llolding or 

There was little discussion on zoonotic 

infections associated with handling strandlings. 

Though problems of this kind are nDt common, 

handling stranded marine mammals levertheless 

carries certain health risks (Gerlci and Lounsbury 1993). Rehabilitation centers are 

re:jponsible for making their staff aware that 

certain conditions may be transmized to handlers. Among these are "seal-finger" (Beck and 

Snlith 1977) caused by a mycoplasina (Madoff 

et al. 1991), a condition on the Pacific coast 

known by the same name but causec by a bacteri~~m (Suer and Vedros 1988), influenza (Webster et al. 1981), parapox virus (Hicks and 

Worthy 1987), calicivirus (Smith 1.t al. 1978) 

and Lobo's disease (Symmers 198:;). The unusual occurrence of rabies in a ringed seal 

(Phoca hispida) (Odegaard and Kroj;srud 198 1) 

has raised the possibility of even more serious 

threats. Any number of bacteria call be a problern to susceptible individuals (Geraci and 

Ridgway 199 1). 

- Euthanasia 

Euthanasia is the humane allernative for 

animals unlikely to recover from their illness or 

injury. [Techniques and issues relati -~g to euthanasia of marine mammals have since been 

reviewed (Geraci and Lounsbury 1393)l. The 

procedure is generally accepted arnong those 

involved with strandings, but the criteria for 

employing it, the Workshop reve<iled, differ 

among facilities and with circumstances. 

Some use flexible criteria that take into 

account the animal's condition and p,-ospects for 

release, and available resources. Wllen filled to 

capacity and faced with new arrivals, they 

maintain a constant number by euthanizing 

animals in poorer health and concentrating care 

on those with better prospects. Others employ 

a firmer routine based almost enti-ely on the 

animals' medical condition. As space diminishes, this approach places press Ire on the 

quality of animal care and either conflicts with 

releasing animals. Participants distinguished 

between "medical" and "non-medical" euthanasia. While euthanasia for medical reasons was 

determined to be the decision of the attending 

veterinarian, killing for non-medical reasons 

(e.g., lack of space) alone was considered unethical. 

Euthanasia is a sensitive issue for some 

centers that rely on public funding and volunteer 

staff. Participants expressed concern that resorting to this alternative except in extreme cases is 

often interpreted by the public as a failure of the 

rehabilitation program. Euthanizing an animal 

in irreversible condition at the outset, before 

care-givers invest time and emotion, will help 

reduce staff disenchantment and frustration. 

RELEASE 

Preparation 

Rehabilitated animals are normally 

given some type of medical examination before 

being released. The purpose is to ensure that the 

animal is healthy enough to live a reasonably 

normal life, cope with conditions endemic in the 

wild, and not place the population at: risk by 

introducing serious pathogens. Yet, participants 

agreed that freedom from detectable disease 

alone is no guarantee that the animal will thrive. 

Some animals, held for lengthy periods 

in captivity or raised from birth without the 

benefit of maternal (milk-borne) antibodies, 

may lack immunity to pathogens ubiq~uitous in 

the wild. Prolonged therapy with antibiotics or 

immunosuppressive agents such as corticosteroids may also abate the immune response. 

The pre-release examination sllould hellp define 

whether the animal is immunologically competent to meet the microbial cllallenges in the wild, 

but many important aspects of immune function 

are not evaluated by the routine tests currently 

employed. A full panel of immunological 

assays, including lymphocyte culture and anti- 
body production, is beyond the scope of most release or establish a contingency fund to cover 

diagnostic laboratories. the cost. 

A certain degree of p-e-release conditioning may be needed to prepare the animal to 

sustain itself, depending on the species, the 

reason it came ashore, and the length of its stay. 

The environment during the iransition period 

should promote a diminishing dependence on 

humans and greater opportunity for socializing 

with conspecifics. This period will enable 

experienced handlers to assess the animal's 

ability to interact normally w~th others. Live 

prey given to advance the animal's progress, 

though desirable, is costly, time-consuming and 

not a general practice. Participants were not 

convinced that this was necessaiy for all species. 

The release of an animal should be 

planned to give it a reasonable chance of meeting others of its kind. Current guidelines require 

that this be done. Many of the coastal species 

have predictable movements 01. migrations that 

are linked to environmental conditions such as 

food availability and oceanic temperatures, and 

encompass breeding or molting cycles. Certain 

animals, such as sea otters, distribute according 

to age and sex (Garshelis and Garshelis 1984, 

Jameson 1989). Finding a suitable time and 

place to release an animal of this kind may not 

be difficult or costly, but it may be for others. 

Hooded (Cystophora cristata), harp and ringecl 

seals from the Canadian Arctic have foundered 

ashore as far away as Florida and California 

(Odell 199 1, Dudley 1992). Re turning them to 

their home waters would require agreement 

between corresponding agencies in two governments and transportation over long distances. 

The practice may also provoke adversity among 

maritime residents who may n3t welcome the 

return of a stray. This clearly presents a dilemma, which for the moment :an be resolved 

by simply maintaining animals that cannot be 

released locally. Limited space will inevitably 

cancel that option and will creatc: pressure either 

to stop rescuing such strays, relax conditions of' 

Monitoring 

The effectiveness of a rehabilitation 

program is best gauged by assessing post-release 

survival, but current programs were judged 

unequipped, unprepared and underfunded for 

this task. The most cost-effective approach is to 

apply a mark or tag so that the bearer can be 

identified if it restrands. But estimates of survival based on such recoveries are misleading 

because most animals die at sea and not on the 

beach. Resighting or tracking an animal provides a better indicator of its recovery (Seagars 

1988, Scott et al. 1990, Harvey 19'91). Satellite 

telemetry units, while providing accurate and 

reliable data, cost $2,000-5,000 each, and are 

too expensive to be applied to every animal 

released. Conventional radio telemetry is less 

costly, perhaps a few hundred dollars per unit, 

but requires the expense of a dedicated vessel 

for tracking animals offshore (Mate 1989). 

Thus, in most cases, we are not in a position to 

evaluate and compare release programs on the 

basis of survivorship. 

Yet such data are needed, especially to 

guide decisions about individuals that are at best 

marginal when returned to the wild. Are "target 

weights" reasonable and useful criteria? Can 

animals compensate for physical impairment 

such as blindness? Answers to such questions 

are necessary to ensure that humane decisions 

are made on behalf of the animal (see Critical 

Needs and Recommendations). 

At what point is a released animal fully 

integrated? Some argue that the whole exercise 

has no benefit to the populatiori unless the 

individual reaches sexual maturity and reproduces (Le Boeuf, this report). At the very least, 

the animal should have an annual e:ipectation of 

survival appropriate for its age class in that 

population. Anything less has simply postponed 

the animal's fate by the number of days or 

months it was undergoing rehabilitation. 
Currently, federal agencies encourage nionitoring to ensure they are not counterprothe application of some mark or tag to all re- ductive. For others, this is not an issue. 

leased marine mammals. For some threatened Marine mammals have comp1e:x and species, such as manatees, sufficient funds have sometimes fragile social orders that might suffer been allocated to support satellite tracking from arbitrary reintroductions. Territoriality studies as part of the recovery plan (Sirenia and male competition is a dominant feature of Project 1991). However, for virtually ~11 others, the life history of many species. To spare young rehabilitation centers must finance the monitor- male elephant seals from damaging encounters ing programs themselves, often through public with aggressive bulls, releases are scheduled donaitions. outside the breeding season 9. We know the 

Associated Risks 

Biological and Social Disruption 

Rehabilitation centers deal with animals 

that rnay be unfit and unable to compete. To 

encourage their rehabilitation and release may 

therefore propagate maladaptive trails. This 

reasol~ling underlies selective reintrod~~ction of

golden lion tamarins (Montali and Bush, this 

report). However, there is no evidence linking 

marine mammal strandings to genetic defects. 

Most strandlings are victims of circurnstances 

that have more to do with chance than biological 

inadequacies, and returning them to their natural 

habita~t was considered unlikely to promote 

undesirable genetic characteristics because the 

number of reintroductions is truly small compared to the size of the parent population. 

Paradoxically, threatened or endangered species, 

which stand to gain most from reintroductions, 

face a greater risk because each animal may 

make a significant contribution to the relatively 

small genetic pool. 

At the other end of the spectrum, consider a population near or at the carrying capacity of the environment. Competition for food 

and habitat might be an important factor contributing to the incidence of strandings. W11uld the 

return of a strandling place still more burden on 

the habitat and increase the competiiion for 

limited resources? Some stocks, such ;is those 

of harbor and gray seals in the wester11 North 

Atlantic, sea otters in parts of Alaska, and California sea lions may be approaching this limit. 

Release programs for these species bear close 

detrimental effect of an unbalanced sex ra,tio on 

female Hawaiian monk seals (Hiruki et al. 

1993), and for this reason, males are simply not 

released (Gilmartin 1983, Gilmartin 1990). We 

can only speculate on what might happen if a 

disproportionate number of male bottlenose 

dolphins attempted, upon release, to force their 

way into a stable group. The consequent disruption may offset any benefit that the individual or 

the population might gain by the reintroduction. 

Reintroductions may take on a political 

dimension if they compound already existing 

problems between marine mammals and people. 

Conflicts between commercial fisheries and 

marine mammals have already led to control 

measures such as removing or trans1oc:ating 

offending animals (Rathbun et al. 1990). Workshop participants felt that released animals were 

no more likely than members of the wild population to become "nuisance animals" interfering 

with fisheries by raiding nets or long-lines. 

Other behaviors are not only annoying but can 

be risky. For example, California sea lions 

sometimes return to the care facility after release 

(Ridgway and Robison 1985) or seek attention 

and food from humans. Though infrequent, 

such occurrences are highly visible and command attention out of proportion to the extent of 

the problem. 

Disease 

Looming large in the minds of rehabilitators is the prospect of introducing 

serious disease. Miller (this report) has cited 

several examples of the harm of exposing naive 
populations of terrestrial animals to virulent 

organisms. This threat for marine mammals has 

been accentuated by the recent rash of mass 

mortalities caused by morbilli~ irus infection in 

pinnipeds and cetaceans (Domingo et al. 1990, 

Kennedy 1990, Heide-Jorgensen et al. 1992). 

Because the virus has a broad geographic anti 

biological range, there is heated debate over 

what should be done with rehabilitated animals 

that have been infected, as eviaenced by serum 

antibodies. Are these animals potentially infective to others and therefore a risk when released, 

or are they merely indicators of an endemic: 

infection in the population, posil~g no additionall 

threat? Workshop participants urged the formation of an expert panel (see Crltical Needs anal 

Recommendations) to recommend a framework 

for dealing with this and other viral conditions. 

among them influenza (Geraci et al. 1982), 

herpes (Osterhaus et al. 1985, Kennedy et al. 

1992), and caliciviruses (Smilth et al. 1973, 

Smith 1987), and others sure to emerge as we 

broaden our understanding of marine mammal 

pathogens. 

Other conditions that might be threatening on a smaller scale include leptospirosis, 

especially in California sea lion:; (Dierauf et al. 

1985), and tuberculosis in Australian sea lions 

(Neophoca cinerea) (Forshaw and Phelps 199 1). 

Marine mammals also harbor a host of parasites 

(Delyamure 1955) with identifiable effects on 

the individual (Geraci and St. Aubin 1987). 

However, parasites in their natural host and 

carried by released animals are not considered to 

have the same potential for population-wide 

impact. 

We are not likely to precipitate a serious 

problem when dealing with ~on~ditions that are 

endemic in local populations. The danger lies in 

returning, to a distant naive population, a stray 

that may have encountered fort:ign pathogens 

somewhere along the way. Scrutiny for exotic 

diseases will help prevent the k:nd of problem 

that arose when a spirurid intestinal nematode of 

the slow loris (Nyctecebus couccrng) was introduced into golden lion tamarins (Montali and 

Bush, this report). Such an event in a marine 

mammal population would cancel any benefit 

derived from saving a few strandlings and would 

encourage more stringent, perhaps impossible, 

criteria for release. Rather than risk introducing 

disease, most participants concurred that they 

would chose to retain or euthanize suspect 

animals. 

THE REGULATORY PROCESS 

In the United States, the h4arine Mammal Protection Act (MMPA) placed all activities 

relating to these animals under the jurisdiction 

of the National Marine Fisheries Service and the 

Fish and Wildlife Service. With this jurisdiction 

comes the authority to license and control rescue 

and rehabilitation operations. Though not as 

far-reaching as the MMPA, some legislation 

exists in many other nations, requiring that 

treatment centers operate in accordance with 

government agencies or programs. Participants 

representing centers and government agencies 

expressed their views on how current policies 

affect their operations. 

In the 20 years since the MMPA was 

enacted, arrangements between rescue and 

rehabilitation centers and government agencies 

in the US have evolved to the point where most 

of the activities have become routine and based 

on mutual understanding. Though regulations 

seem to be clear, some participants felt that 

implementation was uneven, reflecting different 

priorities among regions. For example, some 

regions are more insistent than others in enforcing the requirement that all stranded animals be 

eventually released. For example, pressure to 

release a sea otter is greater in California than in 

Alaska. Such practice may encourage either 

premature release or inappropriate detention. In 

view of regional differences in priorities, social 

attitudes, and animal populations, it is unrealistic to expect that a national policy would be 

applied consistently throughout the country. 
While fulfilling their own mission, 

rehabilitation centers perform a service for lacal, 

state and federal government agencies by rescuing animals in distress, removing carcasses that 

are a potential public health risk from the beach, 

and collecting baseline data which help to formullate marine mammal management plans. 

Rehabilitation centers not only bear the cost of 

care and treatment, but also must collect samples 

and conduct viral screening, apply tags when 

anitnals are released, maintain records, and 

prepare timely reports on their activities. Yet, in 

the US at least, no reimbursement is provided or 

expected, except to support programs for endangered species. 

Participants agreed that government 

agencies must continue to support recovery 

efforts for endangered marine mammals; the 

Florida Manatee Recovery Plan (US Fish and 

Wildlife 1989) is one such example. Some 

expiressed concern that there is no analogous 

policy nor funding for rehabilitating animals 

from robust populations. They argued that 

benefits derived by government agencies from 

the rescue centers' activities warraint at least 

some financial support. 

CRITICAL NEEDS AND 

RECOMMENDATIONS 

In the course of the discussions, workshop participants were able to make a number of 

procedural recommendations, many of'which are 

noted throughout the text of this report. Some 

exarnples include advocating training programs 

for staff, encouraging more efficient mechanisms 

for rnoving animals across internaticnal borders, 

and requiring that new arrivals be quarantined. 

For (other issues left unresolved, the participants 

recommended the formation of expert committees to deal with: standards for care and facilities, criteria for releasing rehabilitated animals, 

risk!; of introducing disease, and determining 

survivorship through monitoring released animal:;. The committees would develop further 

recommendations to address the folllowing 

critical needs. 

Inspection and Licensing 

Standards of marine mammal care as 

governed by APHIS regulations do not apply to 

stranded animals unless they become part of a 

permanent exhibit or research colony. Yet most 

of these regulations are in keeping with what is 

known of an animal's basic needs in captivity, 

irrespective of duration. Exceptions might be 

the amount of pool and haul-out space needed 

for temporary housing, and social groupings 

required over the short term. A panel of ,medical 

iind husbandry specialists is needed to establish 

which of the existing APHIS standards are 

appropriate for a rehabilitation facility, and to 

provide an explanation and a substitute recommendation for any regulation determined to be 

inapplicable. If adopted, at least on a voluntary 

basis, such guidelines will ensure a more uniform level of basic care and humane treatment, 

and increase the likelihood that animals will 

meet the criteria for release in reasonable time. 

It will remain for regulatory agencies to decide 

whether or not to implement a licensing and 

inspection procedure based on these standards. 

Criteria for Releasability 

A panel of medical and behtavioral 

specialists is needed to recommend criteria for 

assuring that released animals will prosper 

humanely and pose no undesirable risk. to the 

wild population. The guidelines should include 

a recommended set of medical determinai~ions by 

species, with appropriate reference ranges for 

blood constituents and other clinical measures, 

morphometric limits (weight at length ar~d age), 

a checklist for physical examination, and a 

means of scoring behavioral attributes that 

would influence survival in the wild. Minimum 

values should be set for each of these criteria, 

such that no animal failing any measure would 

be released. The panel would incorporate the 
While fulfilling their own mission, 

rehabilitation centers perform a service for lccal, 

state and federal government agencies by rescuing animals in distress, removing carcasses that 

are a potential public health risk from the beach, 

andl collecting baseline data which help to formulate marine mammal management plans. 

Rehabilitation centers not only bear the cost of 

care and treatment, but also must collect samples 

and conduct viral screening, apply tags when 

animals are released, maintain records, and 

prepare timely reports on their activities. Yet, in 

the US at least, no reimbursement is provided or 

expected, except to support programs for endangered species. 

Participants agreed that government 

ageincies must continue to support recovery 

efforts for endangered marine mammals; the 

Florida Manatee Recovery Plan (US Fish and 

Wildlife 1989) is one such example. Some 

expressed concern that there is no analogous 

policy nor funding for rehabilitating animals 

from robust populations. They argued that 

benefits derived by government agencies from 

the rescue centers' activities warrant at least 

some financial support. 

CRITICAL NEEDS AND 

KECOMMENDATIONS 

In the course of the discussions, workshop participants were able to make a number of 

procedural recommendations, many ofwhich are 

noted throughout the text of this report. Some 

examples include advocating training programs 

for staff, encouraging more efficient mechanisms 

for moving animals across internaticnal borders, 

and irequiring that new arrivals be quarantined. 

For other issues left unresolved, the participants 

recommended the formation of expert committees to deal with: standards for care and facilities, criteria for releasing rehabilitated animals, 

risks of introducing disease, and determining 

survivorship through monitoring released animals. The committees would develop further 

recommendations to address the following 

critical needs. 

Inspection and Licensing 

Standards of marine mammal care as 

governed by APHIS regulations do not apply to 

stranded animals unless they become part of a 

permanent exhibit or resealch colony. Yet most 

of these regulations are in keeping with what is 

known of an animal's basic needs in captivity, 

irrespective of duration. Exceptions niight be 

the amount of pool and haul-out space needed 

for temporary housing, and social groupings 

required over the short term. A panel of medical 

and husbandry specialists is needed to establish 

which of the existing APHIS standards are 

appropriate for a rehabilitation facility, and to 

provide an explanation and a substitute recom- 

~nendation for any regulation determined to be 

inapplicable. If adopted, at least on a voluntary 

basis, such guidelines will ensure a more uniform level of basic care and humane treatment, 

and increase the likelihood that animals will 

meet the criteria for release in reasonable time. 

It will remain for regulatory agencies to decide 

whether or not to implement a licensing and 

inspection procedure based on these standards. 

Criteria for Releasability 

A panel of medical and behavioral 

specialists is needed to recommend criteria for 

assuring that released animals will prosper 

humanely and pose no undesirable risk to the 

wild population. The guidelines should include 

a recommended set of medical determinations t3/ 

species, with appropriate reference ranges for 

blood constituents and other clinical measures, 

niorphometric limits (weight at length and age), 

a checklist for physical examination, and a 

means of scoring behavioral attributes that 

would influence survival in the wild. Minimum 

values should be set for each of these criteria, 

such that no animal failing any measure would 

be released. The panel would incorporate the 
recommendations of the group considering the 

risks associated with specific pathogens, particularly for "carriers" that are otherwise normal and 

healthy. 

Disease Transmission 

Marine mammals are exposed to pathogens, certain of which may jeopardize the health 

of populations. A panel with expertise in marine mammal medicine is needed to review the 

known infectious agents of each marine mammal group, rank them according to their potential to transmit disease, and determine which 

pose an unacceptable risk if introduced to the 

marine environment. The panel s hould recommend to the Working Group on Criteria for 

Releasability (see above) procedures for identifying these agents or exposure to them. It 

should define the clinical condition or carrier 

state that determines if and when an animal 

exposed to these pathogens can be released. The 

panel also should consider and, as possible, 

recommend procedures for detecting and avoiding the spread of new infectious agents. 

Monitoring 

A panel of population biologists familiar 

with telemetry technology is needed to review 

available data on survival, assess the efficacy of 

the tagging, marking and tracking techniques 

that have been used, and recommend the best 

approaches to determining mortality rates in 

rehabilitated animals. The group might also be 

charged with designing a study, using representative species for which there are sufficient 

numbers of animals handled, to test the assumptions underlying criteria for release. For example, animals that do not meet target weights or 

are partially disabled but otherwise healthy, 

could be released and tracked along with a 

matched set of individuals in optimal condition. 

Such a study might reasonably be funded by 

federal agencies seeking to resolve uncertainties 

over the efficacy of rehabilitation and release 

programs. 
ACKNOWLEDGMENTS 

The success of the Workshop was due in large part to the enthusiastic participation of all the 

attendees, and the skillful guidance of the Panel Chairs - R. Hofman, A. Hohn, M. Johnson, B. Le Boeuf, 

and R. Turner. We also thank S. Murphy and M. Patterson for carefully recording the proceedings of 

their groups, and H. Copland for assisting with all aspects of the Workshop, from convening to 

preparation of the report. R. Hofman provided many valuable comments during the preparation of this 

report. Partial financial support was received from the Office of the Dean, Ontario Veterinary College, 

University of Guelph. 

FOOTNOTES 

Present address - Mystic Marinelife Aquarium, Mystic, CT. 

R. Turner, US Fish and Wildlife Service, Jacksonville, FL. 

P.J. Duignan, Dept. of Pathology, University of Guelph, Guelph, Ontario, Canada 

T.J. O'Shea, US Fish and Wildlife Service, National Ecology Research Center, Fort 

Collins. CO. 

G. Early, New England Aquarium, Bostrm, MA. 

G.D. Bossart, Miami Seaquarium, Miami, FL. 

N.J. Gales, Dept. of Conservation, Wellington, N.Z. 

S. Sadove, Okeanos Ocean Research Foundation, Hampton Bays, NY. 

P. Barrett, Marine Mammal Center, Sausalito, CA. 
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MANATEE PANEL 

Greg Bossart 

Miami Seaquarium 

Miami, FL 33149 

APPENDIX I 

DIRECTORY OF WORKSHOP PARTICIPANTS 

Jerry Eberhardt 

Wildlife Preservation Trust 

Philadelphia, PA 19 104 

Milton Friend 

US Fish and Wildlife Service 

National Wildlife Research Center 

Madison, WI 5371 1 

Jim Kraus 

US Fish and Wildlife Service 

Jacksonville, FL 32216 

Dan Ode11 

Sea World 

Orlando, FL 32821-8097 

Robert Turner (Chair) 

US Fish and Wildlife Service 

Jacksonville, FL 32216 

Michael Walsh 

Sea World 

Orlando, FL 32821 

SEA OTTER PANEL 

Carl Benz 

US Fish and Wildlife Service 

Ventura, CA 93003 

Murray Johnson (Chair) 

Marine Mammal Commission 

Washington, D.C. 20009 

Susan Jacobsen 

US Fish and Wildlife Service 

Arlington, VA 22203 

Sue Kruse 

Southwest Fisheries Region 

National Marine Fisheries Service 

La Jolla, CA 92038 

Richard Montali 

Department of Pathology 

National Zoological Park 

Washington, D.C. 20008 

Thomas D. Williams 

Monterey Bay Aquarium 

Monterey, CA 93940 

Scott Wright 

Florida Department of Natural Resources 

St.Petersbug, FL 33701 
CETACEAN PANEL OTARIID PANEL 

Larry Dunn 

Mystic Marinelife Aquarium 

Mystic, CT 06355 

Nick Gales 

Atlantis Marine Park 

West Perth, Australia 6005 

Sylvia Galloway 

Southeast Fisheries Region 

National Marine Fisheries Service 

Charleston, SC 294 12 

Joseph Geraci 

University of Guelph 

Guelph, Ontario, Canada N1G 2W 1 

Dan Goodman 

Department of Fisheries and Oceans 

Ottawa, Ontario, Canada 

Aleta Hohn (Chair) 

Office of Protected Resources 

National Marine Fisheries Service 

Silver Spring, MD 20910 

Sally Murphy 

Sc~uth Carolina Wildlife and Marine 

F:esources Department 

Charleston, SC 294 12 

Ken Ramirez 

John G. Shedd Aquarium 

Chicago, IL 60605 

Sam Ridgway 

Naval Ocean Systems Center 

San Diego, CA 92152 

Robert Schoelkopf 

M,arine Mammal Stranding Center 

Brigantine, NJ 08203 

Ra~ndy Wells 

Conservation Biology Department 

Chicago Zoological Society 

Brookfield, IL 605 13 

Peigin Barrett 

Marine Mammal Center 

Marin Headlands, GGNRA, 

Sausalito, CA 94965 

Donald Calkins 

Alaska Department of Fish and Game 

Anchorage, AK 995 18 

Richard Ferrero 

National Marine Mammal Laboratory 

National Marine Fisheries Service 

Seattle, WA 98115 

Doyle Hanan 

California Dept. of Fish and Game 

C/O Southwest Fisheries Region 

National Marine Fisheries Service 

La Jolla, CA 92038 

Robert Hofman (Chair) 

Marine Mammal Commission 

Washington, D.C. 20009 

Jim McBain 

Sea World 

San Diego, CA 92 109-9980 

William Medway 

School of Veterinary Medicine 

University of Pennsylvania 

Philadelphia, PA 19 104 

Eric Miller 

St. Louis Zoological Park 

St. Louis. MO 63 110-1396 

Dana Seagars 

Office of Marine Mammal Management 

US Fish and Wildlife Service 

Anchorage, AK 99508 

Dean Wilkinson 

Office of Protected Resources 

National Marine Fisheries Service 

Silver Spring, MD 209 10 
PHOCID PANEL 

Sophie Brasseur 

Department of Aquatic Ecology 

Institute for Forestry and Nature Research 

Den Burg, The Netherlands 

Colleen Coogan 

Northeast Fisheries Region 

National Marine Fisheries Service 

Gloucester MA 01930 

Padraig Duignan 

University of Guelph 

Guelph, Ontario, Canada N 1 G 2W 1 

Greg Early 

New England Aquarium 

Bostoli, MA 02 1 10 

Laurie Gage 

Marine Mammal Center 

Marin Headlands, GGNRA 

Sausalito, CA 94965 

William Gilmartin, 

Southwest Fisheries Region 

National Marine Fisheries Service 

La Jolla, CA 92038 

Giinter Heidemann 

Institut Fiir Haustierkunde 

Der Christian-Albrechts-Universitat 

Forschungsstelle Wildbiologie 

Kiel, Germany 

Burney Le Boeuf (Chair) 

Institute of Marine Science 

University of California 

Santa Cruz, CA 95064 

Lloyd Lowry 

Alaska Department of Fish and Game 

Fairbanks, AK 99701 

Peter Reijnders 

Institute for Forestry and Nature Research 

Den Burg, The Netherlands 

Ian Robinson 

RSPCA Seal Assessment Unit 

Norfolk, England PE3 18NP 

Samuel Sadove 

Okeanos Ocean Research Foundation 

Hampton Bays, NY 1 1946 

David St. Aubin 

University of Guelph 

Guelph, Ontario, Canada NI G 2W 1 

Tom Smith 

Department of Fisheries and Oceans 

Pacific Biological Station 

Nanaimo, B.C., Canada V9R 5K6 
CHANGING VIEWS OF ANIMALS: 

THE ETHICAL FRAMEWORK OF REHABILITATION PROGRAMS 

Prepared from a Presentation Delivered by 

Franklin M. Loew 

School of Veterinary Medicine 

Tufts University 

Boston, MA 

America today is much different than it 

was during its development through the last 

century, and this transformation has had a significant impact on its inhabitants' perspectives 

on animals. Ninety-eight percent of the population does not live on farms. Urban Americans 

now own more cats and dogs (1 10 million) than 

there are people in any of the countries of the 

European Community. There are more horses 

now in urban/suburban America (some 7 million 

or so) than at any time since the horse cavalry 

ceased to be an effective fighting force after 

World War I. More horse now graze in Massachusetts than do dairy cattle, the first time that's 

been true for a century. 

The shift away from an agricultural 

society has redefined our behavior toward 

animals (Loew 1993). Urban Americans view 

their cats, dogs and horses more as "companiclns" than as pets, more as fellow creatures than 

as the mere chattels the law still holds them to 

be. And these feelings have been increasingly 

transferred to wild animals. A decade of "animal rights" activism has, in its less extreme 

forms, resonated in the psyches of most citizens 

in the form of concerns about whether animals 

in at least some kinds of research or testing are 

really needed, the ways in which at least some 

kinds of livestock are raised for food, the wearing of furs, and hunting and trapping. Concern 

for the welfare of individual animals now surpasses that for the species in many situations. 

Within this broad framework, there exist 

strong regional tendencies that vary sharply 

across the country. Kellert (1988) has distinguished ten basic attitudes that define fundamental views of animals, and charted the prevalence of these attitudes within various geographic and demongraphic sectors of the United 

States. Most prevalent, and closely linked to the 

evolution from a rural life-style, is the "humanistic" view, which emphasizes feelings of 

strong affection for individual animals. Those 

engaged in livestock production, hunters, and 

fishermen see the practical or material value of 

animals from anutilitarian" or "dominionistic" 

perspective. Differences in the public and 

political response to stranded marine mammals 

can be traced in some measure to the strength of 

these value sets within each region of the nation. 

While some groups in the population are 

well informed of issues concerning wild animals, the American public as a whole has an 

extremely limited knowledge of animals (Kellert 

1988). The problem of biological iilliteracy in 

society complicates the decision-making processes of politicians and government agents, 

who must perform an ethical calculus that 

incorporates factors such as time, money and 

politics against a broad, and sometimes conflicting, ethical framework within each geographical 

region. Combining national and local perspectives into a generally accepted value system may 

prove to be a difficult challenge. 
Among wild animals, marine mammalls 

are viewed with a particular reverence. Strong 

opposition to seal harvests and the whaling 

industry resulted in significant reduction or 

elimination of these activities on an international scale. Attention has now shifted to the 

issue of marine mammals in captivity. Initially 

this attention was to ensure high standards for 

maintaining the animals in good health, but it is 

evolving into the more fundamental question of 

the moral justification for confining them at all. 

Confinement for the purpose of rehabilitation is 

more readily accepted. There is widespread 

public support for the rescue of a stranded 

marine mammal for its own sake, regardless of 

the scientific or educational motives that might 

underlie such activities (Scheffer 1989). These 

are the values that will chart the course of marine mammal rescue and rehabilitation programs. 

LITERATURE CITED 

Kellert, S.R. 1988. Human-animal interactions: a review of American attitudes to wild and domestic 

animals in the twentieth century. In AN. Rowman [ed.] Animals and people sharing the 

world, University Press of New England. Hanover, NH. 

Loew, F.M. 1993. Turning plowshares into Volvos: changing American attitudes toward livestock. 

J. Agric. And Environ. Ethics 6 (Suppl. 1): 105-109. 

Scheffer, V.B. 1989. How much is a whale's life worth anyway? Oceanus 32: 109-1 11. 
REHABILITATING STRANDED CETACEANS AND PINNIPEDS: 

MANAGEMENT ISSUES, AND DATA SUMMARY 

Aleta A. Hohn and Dean M. Wilkinson 

Office of Protected Resources 

National Marine Fisheries Service 

133 5 East-W est Highway 

Silver Spring, MD 20910 

It's almost time to go home, Friday afternoon after a long week. Visions of a night on 

the town and a relaxing weekend at home suddenly evaporate when the stranding 

telephone rings. There's a live marine mammal stranded on the beach and it needs help, 

NOW. 

Public lnterest in "saving" marine mammals and the goodwill of professional marine 

mammalogists and various facilities have resulted in an active stranding-rescue network in 

the US. Over the years, these efforts have led to 

an increase in the number of stranded animals 

reh~abilitated and released. Concurrently, there 

has been an increase in concern over the handliing of live-stranded marine mammals, the 

decision-making process involved when releasing, or retaining treated animals, and potential 

impacts of releasing animals into wild populatioi~s. 

Since the passage of the Marine Mammal Protection Act (MMPA) in 1972, the National Marine Fisheries Service (NMFS) has 

developed regufations, policies, and recommendations regarding the proper response to stranded cetaceans and pinnipeds (except walrus), and their dispositions once they are rehabilitated (Wilkinson 1991). This paper focuses on 

these issues, summarizes existing data and 

concludes with recommendations for standards 

in treating and releasing cetaceans and p 

innipeds. Walruses, sea otters, manatees, dugorigs and polar. bears are under the jurisdiction 

of the Fish and Wildlife Service, and are not 

corisidereti here. 

In this paper, we make a distinction 

between rehabilitate and treat. Webster's I1 

dictionary defines rehabilitate as "to restore ... to 

customary activity through education and therapy" and treat as "to give medical aid to". 

Although the goal is to rehabilitate live-stranded 

marine mammals, it is seldom known whether 

individuals that have been treated and released 

have in fact been rehabilitated. 

APPLICABLE STATUTES, 

REGULATIONS, AND POLICIES 

Statutory Requirements 

The MMPA explicitly states that rescued marine mammals be released if feasible 

and the animals are judged likely to survive 

(Section 109(h)(3)). However, NMFS has 

adopted the policy that the welfare of the wild 

population overrides that of any individual. In 

other words, release must not be to the detriment 

of the wild population, and may be denied if 

NMFS determines that an unnecessary risk 

exists. This authority has been exercised recently, for example, in preventing release of 

pinnipeds with titers to morbillivirus because it 

was uncertain whether the animals were infectious. 
Mandatory release may also be sus- Permanent Retention of Treated Animals 

pended for reasons other than a potentia1,ly There are no specific regulations or adverse effect on a population. For example, policies for retaining animals except those that live-stranded pinnipeds have been retained for might pose an unnecessary risk to the wild public display in lieu of removing others from population. Generally, that decision is made by the wild '. the attending veterinarian. Unreleasable animals - 

- Animals on the Beach must enter a permanent colony or be euthanized. 

In practical terms there are no regulations, policies, or guidelines for rescuing ;an 

animal on the beach, transferring it, or e u 

thariizing it. The MMPA, as passed in 1972, 

generally viewed both live and dead stranded 

marine mammals as public health hazards which 

are the responsibility of local governments. The 

value of stranded animals to science and conservation was pointed out in a 1977 workshop 

(Geraci and St. Aubin 1979), and in 1981 the 

Act was amended to allow federal involvement. 

Subsequently, NMFS established regional 

marine mammal stranding networks. 

Three NMFS regions (Northeast, Northwest, Southwest) have a policy that pinnipeds be 

observed for 24-48 hours before any action is 

taken. Currently the decision on the fate and 

handling of a beached animal lies with the 

attending veterinarian or qualified member of 

the stranding network; qualified individuals are 

identified as such when authorized to participate 

in a stranding network (i.e., in a Letter of Authsrization from the regional offices of NMFS). 

At the Rehabilitation Facility 

The course of medical treatment at a 

rehabilitation facility is left to the discretion of 

the attending veterinarian. NMFS has not 

suggested treatment protocols or standards, but 

provides two guidelines on maintenance: animals undergoing rehabilitation are to be segregated from those used for public display during 

an unspecified quarantine period; and animals 

undergoing rehabilitation are not to be used for 

public display. 

Those retained must be placed in a 

facility that meets APHIS (Animal and Plant 

Health Inspection Service, US Department of 

Agriculture) standards. Until recently, regional 

offices of NMFS issued a Letter of Agreement 

authorizing public display facilities for this 

purpose; a public display permit was not required. This procedure had the advantage of 

allowing expeditious placement of animals and 

reducing the burden on facilities providing 

treatment. It also circumvented public review 

regarding the placement of animals, and precipitated a controversy when, in 1989, a bottlenose 

dolphin (Tursiops truncatus) was permanently 

placed under a Letter of Agreement in a facility 

that did not have a public display permit. As a 

result, NMFS policy was changed to require that 

facilities lacking such a permit had to obtain one 

following inspection and full public review 

before they could permanently retain a cetacean. 

The policy of placing rehabilitated pinnipeds in 

public display facilities under Letters of Agreement has continued. 

Non-releasable animals may also be 

used for scientific research. Authorization for 

this purpose requires a scientific research permit. 

Releasing: Treated Animals 

In the past, NMFS has left the determination of releasability to the individual institutions. This practice is being re-evaluated, particularly for cetaceans. As a first step, NMFS 

placed conditions on the release of cetaceans, 

and applied them on a case-by-case basis. The 

conditions include: (1) "normal" swimming 

behavior (upright orientation and multidirectional movements), (2) stable body weight 
maintained by freely feeding animals, (3) "normal" blood chemistry and hematology, and (4) 

no indication of infectious disease. In 1991, 

additional conditions delayed for several months 

the release of a harbor porpoise (Phocoena 

phocoena) calf that had stranded on the Pacific 

coast. NMFS required that the animal be retained until it was closer to the estimated age at 

weaning for this species, and others of its kind 

had ,returned to nearby waters. 

Once a decision is made to release an 

animal, NMFS has three additional requirements. The facility must notify NMFS of the 

release, the animal must be tagged ', and the 

release must be in the vicinity of conspecifics. 

An exception to the last requirement has been 

authorized in the Northeast Region where an 

increasing number of species are stranding 

(including gray seals, Halichoerus grypus, 

hoocled seals, Cjjstophora cristata, and harp 

seals, Phoca groenlandica) outside the core 

range of their populations. Releasing these 

species in their core range may not be feasible. 

As sm alternative, the Northeast Region has 

adopted a policy that release could be in the 

vicinity of the original stranding at the same 

time of year. NMFS also recommends that a 

speciies normally occurring in social groups in 

the wild be released in the vicinity of others of 

the same species or that at least two treated 

individuals be released simultaneously. 

It has been standard practice for NMFS 

Regions to require that released animals be 

mark.ed or tagged. The Southwest and Northwest Regions provide roto-tags for this purpose. 

Additional information about the movements 

and, possibly, survival of released animals can 

be obtained by attaching radio tags or satellitelinked transmitters. Until recently, a scientific 

research permit was required to apply any type 

of tai;. Recognizing the need to verify survivorship of animals rehabilitated and released, 

NMFS changed the policy, and no longer require:~ a permit to tag cetaceans or pinnipeds 

with transmitters prior to release 3. 

THE NUMBER OF PINNIPEDS AND CETACEANS RELEASED OR RETAINED 

NMFS regional offices maintain records of cetaceans and pinnipeds taken to rehabilitation facilities. The data presented here 

are based on reports submitted by the rehabilitation centers for 1973-1991, and include all 

regions of the continental United States. Data 

on the number of number of animals permanently retained in captivity are likely accurate 

because they come from various sources. These 

include the NMFS inventory of captive marine 

mammals, Letters of Agreement for transferring 

or holding in captivity, and permit records. In 

this paper, an animal is considered "retained" if 

it had been (1) held at least one year without a 

formal decision to retain it permanently, or (2) 

if a formal decision was made, by Letter of 

Agreement or permit, for permanent care even if 

it died within one year of that determination. 

Excluded from the data set are animals that died 

within one year without a formal determination 

on their status, and those held longer than a year 

but later released. The latter category applies 

more frequently to cetaceans. 

Records are less complete on stranded 

pinnipeds and cetaceans that were released. 

Most, if not all, of the cetaceans in this category 

have been accounted for since 1973 but in some 

cases the exact dates (or even years) of stranding 

or release are uncertain. Data on released pinnipeds have been systematically kept only in 

more recent years: since 1982 for California sea 

lions (Zalophus callfornianus) and northern 

elephant seals (Mirounga angustirostris) in the 

Southwest Region, and since 1986 for all other 

species including Mirounga in the Northwest 

Region. 

Most of the live-stranded individuals 

taken to rehabilitation facilities are pinnipeds 

(Fig. 1); the majority of those are California sea 

lions, followed by elephant seals and harbor 

seals (Phoca vitulina). Seven other species have 

been recorded (Table 1). The recorded number 

of individuals of all species of pinnipeds that are 

treated and released has generally risen since 
1973 (Fig. 1). Some of the increase may be 

attributed to better reporting and record keeping, 

but other factors are likely involved as well. 

These include greater effort to rehabilitate, 

improved medical knowledge, better equipped 

facilities, and recent catastrophic events that 

resulted in large numbers of strandings. Expanding populations or range extensions may 

also account for an increase in strandings. 

The marked annual variation in stranding records for Zalophus reflects the combined 

influence of epizootics and environmental 

~zonditions. A 1983 outbreak of leptospirosis 

coincided with a significant El Nifio - Southern 

~3scillation event that affected the coastal waters 

of California (Trillmich and Ono 1991). Two 

other leptospirosis outbreaks account for increases in the number of stranded Zalophus in 

1988 and 199 1, the latter also including animals 

affected by other diseases. The comparatively 

low numbers in 1985-87 likely reflect more 

normal stranding rates, and are not an artifact of 

incomplete records, which on Zalophus have 

been systematically kept since 1982. 

Very few cetaceans are treated (Fig. 1) 

Individuals representing twelve species have 

survived long enough at rehabilitation facilities 

to be released or considered permanently captive 

(Table 2): the most common are pilot whales, 

(7lobicephala rnacrorhynchus and G. rnelm, and 

bottlenose dolphins. Only one or two individuals from each of the eight remaining species has 

been treated. 

Most cetaceans die on the beach or 

shortly after arriving at a treatment facility. 

Even in mass strandings, where some of the 

elnimals may not be "sick!, the stranding event 

itself can cause physiological stress, shock and 

t~yperthermia. Without timely intervention, 

animals in this condition are unlikely to survive. 

In addition, logistic difficulties are great. Some 

animals are too large to transport, or be kept at 

a rehabilitation facility. The number of cetaceans treated at rehabilitation facilities remained 

relatively constant at low levels from 1973-1990 

(mean =: 2. llyear) then increased in 1991 when 

12 live-stranded cetaceans were collected. 

Though dwarfed by the hundreds of pinnipeds 

that are now being treated and released each 

year, the few cetaceans released or retained 

draw considerable public attention and controversy. 

The number of stranded marine mammals placed in permanent captivity has varied 

widely since the passage of the MMPA (Fig. 1). 

In 1977, NMFS adopted a policy to place rehabilitated pinnipeds in lieu of a take from the 

wild. Almost without exception, no permit has 

been issued since that time allowing a pinniped 

to be taken from the wild for permanent captive 

maintenance. This policy is reflected in the 

large number of Zalophus retained in 1978 and 

1979. Subsequently, the numbers of pinnipeds 

retained has declined, reflecting a saturation of 

public display facilities. Only a few treated 

pinnipeds or cetaceans are now retained in 

permanent captivity (Fig. 1). 

The profile of retained species is driven 

by the number that strand, the size of the animal, 

and the cost of maintenance. As with California 

sea lions, more elephant seals have been released than retained (Figs. 2 and 3). In contrast, 

about as many harbor seals and cetaceans have 

been retained as released (Figs. 4 and 5). Most 

of the other pinniped species strand outside their 

expected population range, and most of them are 

released. 

RECOMMENDATIONS 

The biological justification for rescuing 

and rehabilitating most stranded marine mammals is arguable. Such efforts do not contribute 

to the enhancement of most species. For that 

reason, NMFS provides few resources for 

rescue programs. However institutions dedicated to this end are likely to endure and even 

increase in number; centers are now emerging 

with the sole purpose of treating stranded animals. These centers currently are not licensed 

or inspected by APHIS, and therefore operate 

autonomously. 
This raises concern that animals might be released without adequate health evaluation, and 

could pose a risk of transmitting disease to the 

population. Standards are needed that address 

these issues, beginning with criteria for rescue 

and release (Geraci and Lounsbury 1993) and 

guidelines for medical and quarantine measures 

(St. Aubin et al. this report) that will safeguard 

the animal and the population to which it is 

introduced. 

ACKNOWLEDGMENTS 

The data included here were reported to the NMFS regional offices by rehabilitation facilities 

and members of the stranding network. We are grateful to Kathy Horstman for assistance in editing 

the data and reports received from the regions. Constructive reviews of the manuscript were provided 

by Cindy Driscoll, Nancy Foster, Brent Norberg, Michael Payne, Michael Scott, Ann Terbush and 

Michael Tillman. 

LITERATURE CITED 

Geraci, J.R. and V.J. Lounsbury. 1993. Marine mammals ashore: afield guide for strandings. Texas A&M 

University Sea Grant College Program. Galveston, TX. 305 p. 

Geraci, J.R. and D.J. St. Aubin (eds.). 1979. Biology of marine mammals: insights through strandings. 

Natl. Tech. Inf. Serv., Springfield, VA. PB293-890. 343 p. 

Trillmich, F. and K.A. Ono (eds.). 1991. Pinnipeds and El Niiio: responses to environmental stress. 

Springer-Verlag, New York. 293 p. 

Wilkinson, D.M. 1991. Program review of the marine mammal stranding networks. Report to the 

Assistant Administrator for Fisheries, National Marine Fisheries Service, Silver $ring, MD. 203 

P. 

FOOTNOTES 

I memo from W. Meibohn, Associate Director, NMFS, to the Regional Directors, July 5, 

1977; a copy can be found in Wilkinson 199 1, Appendix D 

implemented as a policy per letter from W.W. Fox, Jr. to NMFS Regional Directors, 

January 9, 1992 

' formalized as a policy per letter from W.W. Fox, Jr. to NMFS Regional Directors, July 9, 1991 
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Figure 1. (see next page) The number of live-stranded pinnipeds and cetaceans transported to a 

rehabilitation facility, treated, then released or retained for permanent captivity. 

Records are complete for all cetaceans and for retained pinnipeds since passage of 

the Marine Mammal Protection Act in 1972. Records are incomplete for (A) 

Zalophus and Mirounga released prior to 1982, except for any Mirounga that might 

have been released in the Northwest Region prior to 1986 (this number is likely to be 

very small, and (B) all other species of pinnipeds released prior to 1986. Retained 

animals are those that either have been determined to be permanently captive and are 

designated as such by Letter of Agreement or permit, or those that have survived one 

year or more as permanently captive animals even if they h~ve not been determined 

to be permanently captive. 
YEAR 

- ................................................................ I. 

I 1 I I I I I I I I I I I I I I I 

'C 3 %b %% %6 Z B~,~,~ 4' 9' 

,9'+ ,9qb ,9'" ,9i6 ,9" ,9i8 ,9i9 ,91° $8, ,9% ,9% ,9 ,9 ,9 4% ,9 ,9 ,9 

YEAR 

-. 

- 

RELEASED I 

t I 

I ................................. 1 ! ............................ 

I\ I 

I' I 

Zalophus I \ I ............................. ...\............... ........ i i 

............ 

- ................... 

4w 

I I I I I I I I I I I I I I I I I 
ZALOPHUS 

----- 

300 250 ZOO 150 100 50 0 50 100 150 ZOO 250 300 

NUMBER RETAINED NUMBER RELEASED 

Figure 2. The number of California sea lions, Zalophus califomianus, treated at a 

rehabilitation facility and released or retained. Data on the numbers released are 

incomplete prior to 1982. For a definition of retained, see Figure 1. 
120 100 80 60 40 20 0 20 40 60 80 100 120 

NUMBER RETAINED NUMBER RELEASED 

Figure 3. The number of northern elephant seals, Mirounga angusfirosfris, treated at a 

rehabilitation facility and released or retained. Data on the numbers of released in 

the Southwest Region are complete beginning in 1982. Although they are not 

complete in the Northwest Region until 1986, relatively few Mirounga have been 

released there. For a definition of retained, see Figure 1. 
YEAR 

80 6 0 4 0 2 0 0 20 40 60 80 

NUMBER RETAINED NUMBER RELEASED 

1973 - 

1974 - 

197s - 

1976 - 

1977 - 

1978 - 

1979 -- 

1980 - 

1981 - 

1982 - 

1983 - 

1984 - 

1985 - 

1986 - 

1987 - 

1988 - 

1989 - 

1990 -- 

1991 - 

Figure 4. The number of harbor seals, Phoca vifulina, treated at a rehabilitation facility and 

released or retained. Data on the numbers released are incomplete prior to 1986. 

For a definition of retained, see Figure 1. 

PHOCA 

I I I 
YEAR 

CETACEANS 

NUMBER RETAINED NUMBER RELEASED 

Figure 5. The number of cetaceans of all species treated at a rehabilitation facility and released 

or retained. Data should be complete since passage of the Marine Mammal 

Protection Act for both released and retained individuals. For a definition of 

retained, see Figure 1. 
DISEASE AND REINTRODUCTIONS - AN OVERVIEW 

R. Eric Miller 

St. Louis Zoological Park 

Forest Park 

St. Louis, MO 63 110 

Disease can have a major impact on wiM 

populations. Consider the extinction of wild 

black-footed ferrets (Mustela nigripes) and the 

current precipitous decline of the African wild 

dog (Lycaon pictus) due to canine distemper. In 

many cases, disease introductions result from tk 

activities of man. For example, exposure to 

lungworm infections and viral diseases of 

domestic sheep has had a notable and negative 

effect on the North American populations of 

Rocky Mountain bighorn sheep (Ovis 

canadensis). Like the "Hawaiian syndrome" in 

man, where measles nearly exterminated the 

native populations, the potential impact of 

disease introductions in immunologically naive 

wildlife populations is not surprising. 

As reintroductions of rehabilitated or 

captive-bred animals take place, it is critical that 

these new arrivals do not bring with them 

disease entities that will affect the health and 

survival of their compatriots still afield. 

Although this presentation focuses on the 

problems and prevention of disease introduced 

from captive animals returned to the wild, it is 

important to remember that there is similar 

concern when wild animals are translocated to 

areas with diseases to which they have not 

developed resistance. A notable example is the 

introduction of white rhinoceroses 

(Ceratotherium simum) into Kenya's Meru 

National Park. There, several newly arrived 

rhinoceroses died of trypanosomal infections, 

although rhinoceroses already exposed had 

developed resistance and survived. 

Reintroduction of captive animals to the 

wild is not new. Several of the bison (Bison 

bison) herds that currently inhabit the American 

West are descended from animals reintroduced 

from the New York Zoological Society in 1907. 

Arabian oryx (Oryx leucooryx) from the Phoenix 

and San Diego Zoos are currently being used to 

found new herds in the Middle East, and golden 

lion tamarins (Leontopithecus rosalia) from the 

National Zoological Park and other institutions 

are being returned to the coastal Brazilian rain 

forest (Montali and Bush, this report). These 

projects are increasingly important for species 

threatened by dramatic changes in their natural 

habitat (Foose 1983). Captive populations may 

represent the last hope for some. It is now 

estimated that there are more captive Siberian 

tigers (Panthera tigris altaica) (600-700) than 

wild ones (300-400). Other species, such as the 

Asian wild horse (Equusprzwalskii), exist only 

in captivity. 

To maintain the genetic diversity of 

small populations, intensive genetic management 

is required (Soule et al. 1986). Genetic models 

have defined the "saving" of a species as the 

maintenance of 90% of its genetic diversity over 

200 years or 50 generations (Soule et al. 1986). 

That principle is perhaps best expressed by Alcb 

Leopold's statement, "The first rule of intdligent 

tinkering is to save all of the parts." 

Genetic variability encompasses not 

only body shape or color, but also factors that 

affect susceptibility to disease. For example, tl-e 

genetic impoverishment of the cheetah (Acionyx 
jubatus) may be directly responsible for in- Saudi Arabia, tuberculosis was transferred from 

creased morbidity due to feline infectious peri- domestic hoofstock to Arabian oryx being held 

tonitis (FIP) in this population (O'Brien et al. for release. 

No single institution can hold enough 

animals to maintain a genetically viable population, and so cooperative programs have been 

organized. In North America, Species Survival 

Plans (SSPs) are managed under the auspices of 

the American Association of Zoological Parks 

and Aquariums (AAZPA). An integral part of 

these plans is the transfer of animals from 

institution to institution for breeding purposes. 

Though genetically necessary, these transfers 

also increase the risk of the spread of disease, 

similar to the risks encountered when reintroWe are confident in our ability to diagnose most of these diseases. Yet problems still 

arise. Up to 60% of orangutans (Pongo 

pygmaeus) tested for tuberculosis react positively, but many are "false positive" reactors, 

seriously complicating the interpretation of this 

basic test. Even common diseases can be difficult to diagnose in their acute stages. This has 

been the case with leptospirosis in black rhinoceroses (Diceros bicornis), for which serological 

tests vary widely, leaving only the fluorescent 

antibody (FA) test as a reliable indicator in acute 

infection (Miller et al. 1987). 

ducing animals to the wild or performing A further dilemma can result when a translocations there. biologist asks "What diseases do we need to be 

Many SSP Committees have appointed 

veterinary advisors to help determine what 

diseases are significant in each species. Sound 

conclusions must be based on accumulated 

clinical and post-mortem data, rather than on 

anecdotal or incidental information. Serum and 

tissue banks are integral to retrospective studies 

necessary to determine the history of exposure 

to infectious agents in captive and free-living 

animals. 

Clearly, preventive medicine and testing 

depend on the species involved. The spread of 

tuberculosis in hoofstock and great apes, equine 

rhinotracheitis (a herpes virus) in Asian wild 

horses, paramyxovirus in Aruba Island rattlesnakes (Crotalus unicolor), herpes viruses in 

cheetahs, lion-tailed macaques (Macaca silenus) 

and cranes have been checked by specific testing 

programs. Additional attention must be given to 

preventing mixing species that may carry diseases adapted to one, but dangerous to others. 

For example the virus of simian hemorrhagic 

fever in Patas monkeys (Eeythrocebus patas) 

may be inconsequential to that species, but 

lethal to other primates. It is also important that 

captive species not be exposed to domestic 

animals which may transfer disease to them. In 

concerned about?" In giving a "clean bill of 

health", a veterinarian naturally considers diseases that have already been described in that 

species, and though disease entities continue to 

surface, such as herpetic skin lesions in cheetahs 

(Junge et al. 1991) and coronaviral hepatitis in 

golden lion tamarins (Ramsay et al. 1989), wide 

gaps still exist in our understanding of disease 

agents in a host of other "exotic" species. How 

then can one certify that herpes, retroviral or 

some other viral infection is not significant in 

rhinoceroses or whales or seals? 

Obviously, there are no quick and easy 

answers. The best approach is to develop protocols based on the most current medical knowledge available for each species. To this end, 

centralized data and tissue banks have proved to 

be invaluable. Whether it is a question of releasing long-term captives, captive-born animals, rehabilitated wildlife, or simply translocating free-ranging animals, the issues are often the 

same. Those responsible for regulating the 

transfer and reintroduction of marine mammals 

might benefit by examining programs developed 

by the Captive Breeding Specialist Group 

(CBSG) of the International Union for the 

Conservation of Nature (IUCN). Information 
can be obtained by contacting: 

Captive Breeding Specialist Group 

C/O Minnesota Zoological Park 

13000 Zoo Boulevard 

Apple Valley, MN 55 124. 

LITERATURE CITED 

Foose, T. 1983. The relevance of captive populations to the conservation of biotic diversity, p. 373- 

40 1 In C.M. Schonewald-Cox, S.M. Chambers and B. MacBryde [eds.] Genetics and 

conservation. Menlo Park, CA. 

Junge, R.E., R.E. Miller, W.J. Boever, G. Scherba and J.P. Sundberg. 1991. Persistent cutaneous 

ulcers associated with feline herpesvirus type 1 infection in a cheetah (Acionyx jubutus). J. 

Am. Vet. Med. Assoc. 198: 1057-1058. 

Miller, R.E. and C.A. Bolin. 1987. Evaluation of leptospirosis in black rhinoceroses (Diceros 

bicornis) by microscopic agglutination and fluorescent antibody test. Proc. Am. Assoc. Zoo 

Vet.: 161-162. 

O'Brien, S.J., M.E. Roelke and L. Marker. 1985. Genetic basis for species vulnerability in the 

cheetah. Science 227: 1428- 1434. 

Ramsay, E.C., R.J. Montali and M. Worley. 1989. Callitrichid hepatitis: epizootiology of a fatal 

hepatitis in zoo tamarins and marmosets. J. Zoo Wildl. Med. 20: 178-1 83. 

Soule, M., M. Giipin and W. Conway. 1986. The millennium ark: how long a voyage, how many 

staterooms, how many passengers? Zoo Biol. 5: 10 1- 1 13. 
MODELS FOR DISEASE CONTAINMENT IN CAPTIVE 

TERRESTRIAL MAMMALS DESTINED FOR REINTRODUCTION 

Richard J. Montali and Milton Bush 

National Zoological Park 

Smithsonian Institution 

Washington, D.C. 20008 

Zoological institutions throughout the 

world are propagating threatened and endangered species with the intention ofreintroducing 

and maintaining them in natural habitats. This 

activity is based on major advances made in the 

last 25 years in captive management, nutrition 

and zoological medicine, and the collaborative 

efforts of professionals in the behavioral and 

veterinary sciences. 

The National Zoological Park in Washington, D.C., has developed programs to reintroduce golden lion tamarins (Leontopithecus 

rosalia) to Brazil (Beck et al. 1988) and to reinforce Guam rail (Rallus owstoni) populations by 

establishing them on the island of Rota 

(Derrickson 1987). In addition, cooperative 

programs have been underway to replenish 

natural habitats with black-footed ferrets 

(Mustela nigripes) (Thorn and Williams 1988) 

and more recently red wolves (Canis rufus) in 

the United States. Inherent in such restoration 

programs have been a number of obstacles, not 

the least of which are animal health issues. 

Other programs involving endangered carnivores 

and parrot and crane species have been stymied 

by disease problems (Thom and Williams 1988, 

Cooper 1989, Derrickson and Snyder 1992). 

Therefore, strict guidelines must be developed b 

prevent the dissemination of diseases that might 

arise during the captive breeding phase. 

The purpose of this communication is to 

describe some important types of diseases that 

might develop during in situ propagation of 

endangered animals and to prevent the 

perpetuation of these diseases into wild 

populations during the release phase. Of 

particular concern are genetic and infectious 

diseases, some of which will be illustrated using 

the collaborative program of the Brazilian 

government and the National Zoological Park's 

golden lion tamarin reintroduction program as a 

model (Kleiman et al. 1991). 

Communicable diseases are of utmost 

importance and perhaps the greatest threat to 

annihilating groups of susceptible, valuable 

animals. This process can work both ways. 

Animals from captive sources could transmit 

diseases to conspecifics in the wild and 

potentially to other wild and domestic species in 

the areas of release. Conversely, captive animals 

naive to indigenous infectious agents could 

contract diseases to which the wild population is 

most likely immune. For example, a new 

virulent viral infection of captive marmosets and 

tamarins emerged in the early 1980's with a high 

incidence in the endangered golden tamarin 

(Montali et al. 1989, Ramsey et al. 1989). 

Callitrichid hepatitis virus (CHV) caused fatal 

epizootics at 10 zoos between 1981 and 1991 

before zoo researchers identified the causative 

agent as an arenavirus that was carried by mice 

(Stephensen et al. 1991). The primates were 

exposed to the virus either through their food 

(suckling mice -"pinkiesu) or from contact with 

wild mice inhabiting their exhibits (Montali et 

al. 1993). The overriding concern was that this 
newly emergent disease not be introduced into 

ithe native habitat of this endangered species 

during reintroduction. Preliminary serosurveys 

of wild-born golden lion tamarins from Brazil 

have been negative for CHV antibodies, suggest- 

.[ng that callitrichid hepatitis is not an indigaous 

disease in this species. Efforts to prevent the 

introduction of CHV have included strict quarap 

iiine practices, elimination of mouse-feeding, ad 

csontrol of rodent contact with the animals. 

,Although transmission between tamarins has nct 

lbeen established, those seropositive for CHV 

lhave been eliminated from the reintroduction 

]programs. 

Another medical concern in this species 

involved a spirurid intestinal nematode, 

Pterygoderrnatites nycticebi, whose indigenous 

host is the slow loris (Nycticebus coucang). The 

parasite insidiously adapted itself to the golden 

lion tamarin colony during the earlier propagating phase of this species at the National Zoological Park. Before its recognition as a potential 

problem, it "spilled over" to other tamarin colonies via animal exchanges, resulting in a high 

morbidity but low mortality (Montaliet al. 1983). 

The concern of introducing this captive-adapted 

parasite into the wild was lessened by the fact 

that the German cockroach (Blattela germanica) 

served as an obligate intermediate host and it 

would be unlikely for the parasite to be perpetuated under these conditions in the wild. Fwthermore, the parasite can be eliminated during 

quarantine with effective anthelminthics. 

Animals with genetically-based defects 

are another major area of concern. Recognition 

of a putative familial diaphragmatic defect inthe 

golden lion tamarin led to a diagnostic surveillance program to prevent animals phenotypically 

expressing this trait from being reintroduced 

(Bush et al. 1992). The defects ranged from 

trivial changes to wide gaps that could lead to 

fatal diaphragmatic hernias (Montaliet al. 1980). 

A relatively high incidence 

was reduced precipitously by eliminating overrepresented founders in the breeding stock at 

several facilities. 

In summary, a number of disease problems, both infectious and genetically-based, 

were identified over a fifteen year period in 

captive golden lion tamarins selectively propagated by various zoos for eventual reintroduction. These conditions had been previously 

unrecognized in wild populations. The tamarin 

reintroduction program has served as a prototype 

for developing the rationale and methods to 

prevent the perpetuation of diseases like these 

into areas of release. After approximately a 

decade of reintroducing golden lion tamarins 

into their native habitat in Brazil, none of the 

captive-acquired infectious conditions has yet 

been recognized in survivors of multiplereintroduced groups (Beck et al. 1991). One critical 

element of such a preventative health program 

for reintroduction, therefore, is the capability of 

clinical and pathological monitoring during and 

after the reintroduction period. 

In general, all aspects of this program, 

including breeding strategies and health monitoring procedures, are applicable to most animal 

species whether they be terrestrial or aquatic. 

However, protocols should be tailored to the 

specific disease problems of the species in 

question. Much of the information gained about 

these infectious and genetic conditions in golden 

lion tamarins has been gathered and shared 

globally by breeders through Studbook and in 

the preparation of Species Survival Plans (SSP) 

drafted through the auspices of the American 

,Association of Zoological Parks and .Aquariums 

(AAZPA, now the American Zoo and Aquarium 

Association). Medical protocols for disease 

problems, necropsies and quarantine procedures 

germane to the golden lion tamarin have been 

established and are now in use by all zoos contributing animals to the reintroduction programs. 
LITERATURE CITED 

Beck, B.B., I. Castro, D.G. Kleiman, J.M. Dietz and B. Rettberg-Beck. 1988. Preparing captive-born 

primates for reintroduction. Int. J. Primat. 8: 426. 

Beck, B.B., D.G. Kleiman, J.M. Dietz, I. Castro and B. Beck. 1991. Losses and reproduction in 

reintroduced golden lion tamarins. DODO 27: 50-61. 

Bush, M., B.B. Beck and R.J. Montali. 1992. Medical considerations of reintroduction. In press, In M. 

E. Fowler [ed.] Zoo and wild animal medicine, 3rd ed. W.B. Saunders, Philadelphia. 

Cooper, J.E. 1989. The role of pathogens in threatened populations: an historical review. ICBP Tech. 

Publ. 10: 51-61. 

Derrickson, S.R. 1987. Current status and captive propagation of the endangered Guam rail. Proceedings of the Jean DelacourIIFCB Symposium on Breeding Birds in Captivity, AC Risser [ed.] 

N. Hollywood CA, International Foundation for the Conservation of Birds, p. 187-195. 

Derrickson, S.R. and N.F.R. Snyder. 1992. Potentials and limits of captive breeding in parrot conservation. In S.R. Beissinger and N.F.R. Snyder [eds.] New world parrots in crisis: solutions from 

conservation biology, Washington D.C., Smithsonian Institution Press, p. 133-163. 

Kleiman, D.G., B.B. Beck, J.M. Dietz and L.A. Dietz. 1991. Cost of a reintroduction program and 

criteria for success: accounting and accountability in the golden lion tamarin conservation 

program. Symp. Zool. Soc. Lond. 62: 125-142. 

Montali, R.J., M. Bush, D.G. Kleiman and R. Evans. 1980. Familial diaphragmatic defects in golden 

lion tamarins, p. 173 In Proceedings of the 22nd International Symposium of Diseases of Zoo 

Animals. Arnem. 

Montali, R.J, C.H. Gardiner, R.R. Evans and M. Bush. 1983. Pterygodermaties nycticebi (Nematoda: 

Spirurida) in golden lion tamarins. Lab. Anim. Sci. 33: 194-197. 

Montali, R.J., E.C. Ramsay, C.B stephensen, M.W. Worley, J.A. Davis and K.V. Holmes. 1989. A 

new transmissable hepatitis of marmosets and tamarins. J. Infect. Dis. 160: 759-765. 

Montali, R.J., C.A. Scanga, D. Pernikoff, D. Wessner, R. Ward and K. Holmes. 1993. A common 

source outbreak of callitrichid hepatitis in captive tamarins and marmosets. J. Infect. Dis. 167: 

946-950. 

Ramsay, E.C., R.J. Montali, M.W. Worley, C.B. Stephensen and K.V. Holmes. 1989. Callitrichid 

hepatitis: epizootiology of a fatal hepatitis in zoo tamarins and marmosets. J. Zoo Wildl. Med. 

20: 178-183. 

Stephensen, C.B., J.R. Jacob, R.J. Montali, K.V. Holmes, E. Muchmore, R.W. Compans, E.D. Arms, 

M.J. Buchmeier and R.E. Lanford. 1991. Isolation of an arenavirus from a marmoset with 

callitrichid hepatitis and its serologic association with disease. J. Virol. 65: 3995-4000. 

Thorn, E.T. and E.S. Williams. 1988. Disease and endangered species: the black-footed ferret as a 

recent example. Conserv. Biol. 2: 66-74. 
BEHAVIORAL ISSUES IN RETURNING MARINE MAMMALS 

TO THEIR HABITAT 

Burney J. Le Boeuf 

Department of Biology & 

Institute of Marine Sciences 

University of California 

Santa Cruz, California 95064 

Central to rehabilitating stranded 

animals is the question "does it work?" In the 

broadest sense, we are talking about returning 

animals to their habitat after removal fromit and 

determining whether they survive, resume 

normal activities and reproduce. A priori, two 

categories of variables are expected to influence 

the ease, speed and efficacy of reintroduction. 

The first concerns the cause of initial dislocation 

Successful reintroduction might depend on 

whether initial dislocation from the habitat was 

due to maternal abandonment, illness, accident, 

inclement weather, choice or folce from without 

such as capture. The second set of variables that 

is expected to influence the success of 

reintroduction deals with behaviorally mediated 

effects associated with the period of "habitat 

displacement." These effects can be graded 

along several dimensions: 

1) Temporal dimension. The length of 

time the animal is away from its habitat. This 

may also depend on the animal's age, for critical 

periods of development may be involved. 

2) Spatial dimension. The distance the 

,animal is removed from its habitat (e.g., time 

zones, daylength differences, temperature) and 

how different it is from "home". 

3) Operational or experiential 

dimension. The degree to which the animal is 

affected by the activities experienced during 

detainment, for example drug immobilization, 

blood sampling, forced feeding, and 

manipulation. To what extent did the animal 

experience stress, discomfort, pain, or amnesia 

that would affect its subsequent behavior? 

4) Intrinsic dimension. Change in 

normal behavior, daily rhythm of activities, or 

normal experience as a result of dislocation. 

What did the animal miss during habitat 

displacement that it would normally have 

experienced? 

ASSESSING REINTRODUCTION 

Documenting survival and reproduction 

of reintroduced animals relative to appropriate 

controls is critical for assessing the value of 

rehabilitation or treatments effected during the 

period of removal. Reproduction is the ultimate 

dependent variable, for if an animal does not 

reproduce it does not contribute to the 

propagation of the species. However, although 

rehabilitation and release of injured wildlife has 

become a widespread activity in North America 
(Martell et al. 1991), little effort has been made 

to document survival or breeding success of 

released animals. It is first necessary to 

document whether the reintroduced animal 

survives. If not, why not? Has the dislocation 

lowered the animal's chances of surviving 

relative to conspecifics of the same sex, same 

age, and same health? Has the experience 

affected its foraging success, altered its risk of 

predation, made it more accident prone, made it 

more a risk to conflict with human fishing? 

Is the animal as likely to reproduce as 

"controls"? Is it as likely to wean its offspring? 

Does a female cycle normally, join a harem or 

herd, become receptive to males, conceive, give 

birth and treat her pup normally? Do males 

compete as effectively? If not, why not? 

Assessing reproduction is more difficult than 

assessing survival in most species, and doing so 

with appropriate controls may be possible for 

few species. 

Are the animal's habits changed in subtle 

ways that might eventually affect survival or 

reproduction? For example, does it use the same 

resting sites, breeding sites, molting sites, 

migratory path, foraging areas, etc.? Is it 

received by conspecifics in the area or is it 

treated as an outcast (a lone wolf)? 

Desideratum 

We want to know which variables are 

most important in bringing about successful 

reintroductions. For example, eagles and hawks 

remain near release sites for the first few days 

after release (Servheen and English 1979, 

Hamilton et al. 1988, Martell et al. 1991). 

Reijnders et al. (this report) present evidence 

that some phocid seals do as well. For those 

species, it appears that the release site should be 

chosen so that it fulfills immediate needs of the 

released animal, i.e., food and shelter and no 

humans. Evidently, identifying key variables 

will involve a great deal of parametric study, 

e.g., how long one can hold a dolphin in an 

enclosed tank before it is too late to release it 

successfully and what is the optimal age for 

release of a female harbor seal. An effective 

monitoring program will depend on a complete 

description of the physical condition of the 

animal prior to or at the time of dislocation and 

at the time of reintroduction. It is imperative 

that normal behavior, survivorship, reproductive 

success for a particular agelsex group be known 

in order to fully assess the success of 

reintroduction. That is, one must have a 

standard of comparison. 

BEHAVIOR OF REINTRODUCED 

EXPERIMENTAL SEALS 

To illustrate an approach that a releasemonitoring program might take, I present 

preliminary data on experimentally manipulated 

seals, viewing them as reintroduced animals. 

Some of you may think that this is like the druk 

who lost his wallet in the middleof the block but 

looked for it on the corner because there was 

more light there. But this is not so. 

Reintroduced experimentally treated animals can 

be considered along the same dimensions that 

affect reintroduction of rehabilitated stranded 

animals. The major difference between the two 

is that many stranded animals are initially sick cr 

weak while experimental animals usually are 

assumed to be healthy at the time of capture. 

Treatment during detainment and the duration d 

detainment are often similar. As a result, 

reintroduced experimental animals provide a 

valuable comparison with reintroduced 

rehabilitated animals, or more to the point, a 

control for initial health. 

During the course of a ten year study of 

northern elephant seals (Mirounga 

angustirostris) at Afio Nuevo, California, my 

colleagues and I transported pups and yearlings 

from the rookery to the Long Marine Laborabry 

for a variety of experiments and then returned 

them to the field. We also drugged, restrained, 

and conducted field experiments with seals of 
both sexes and all age groups. Subsequently, we 

sought to determine whether these operations 

affected behavior promoting survivorship and 

reproductive success. 

'Weanlinn Lab Studies 

During the 2.5-month period following 

weaning, elephant seal pups were captured by 

placing a bag over their heads, putting them into 

a cage, and then transporting them by pickup 

truck to the lab 30 km away. Here, the pups 

were housed outdoors in a fenced enclosure on 

a cement slab covered with sand for 2-4 weeks 

and were involved in a variety of experiments to 

study thermoregulation and energy metabolism, 

The studies varied in duration and degree of 

manipulation; most involved blood sampling and 

physical restraint. The animals were not fed 

(unless involved in a feeding experiment) 

because they are normally fasting at this time. 

At the end of experiments, the pups were tagged 

and released in good health at the site where they 

were captured. They weighed approximately 

;!5% less than at the time of capture, the same 

weight loss that untreated pups incur normally. 

lgursing Female Field Studies 

Adult females, 3 to 12 years old, were 

involved in studies of the energetics of lactation 

(Costa et al. 1986) and in the collectionof diving 

data (Le Boeuf et al. 1986, 1988, and 1989). 

Each female was immobilized with ketamine, 

blood samples were taken, and radioactively 

labeled water and Evan's blue dye were injected. 

Each female was weighed and measured and 

kept under low levels of immobilization for up b 

three hours. This procedure was used three 

times during lactation for some females: within 

two days after parturition, in mid-lactation, and 

1-2 days before weaning. For most of them, the 

mid-lactation procedure was omitted. During 

the last treatment, a time-depth recorder and 

radio transmitter were glued to the female'sback 

with marine epoxy. 

Controls 

To evaluate the effects of the treatments 

on the experimental animals, matched controls 

were designated for both weaned pups and adult 

females. The animals were equated with respect 

to several factors that might affect recapture 

rates: sex, weight, time in the season tagged, and 

the number of tags. 

Weanling Survival to One Year of Age 

The survival rate of 74 experimental 

pups to one year of age was not significantly 

different from that of an equal number of contrd 

pups (X2 = 0.027, df = 1, P > 0.05) or from that 

of the population mean (X = 0.164, df = 1, P > 

0.05) (Table 1). Juvenile survivorship did not 

vary significantly as a function of sex (X = 2.5, 

df = 1, P > 0.05), weight at the end of the 

experiment (t = 0.24, df = 65, P > 0.05), the 

number of days held in the laboratory (X2 = 4.90, 

df = 3, P > 0.05), or the date of reintroduction 

into the wild (X2 = 0.22, df = 3, P > 0.05) 

(Tables 1-4). There is a trend for survivorship to 

decrease with time held in the laboratory (Table 

3), so we separated the sample into animals held 

for up to 12 days and those held for longer. 

With this analysis, survivorship was significantly 

lower for animals held for more than 12 days (X 

= 4.51, df =1, P <0.05). 

Adult Female Survival. Reproduction and Site 

Tenacity 

Survival of 43 field-treated adult femalcs 

over the 2.5-month post-breeding period at sea 

was not significantly different from that of an 

equal number of control females, 86% vs. 

88.4%, respectively (z = 0.32, P > 0.05). 

Similarly, there was no difference in site 

tenacity; 45% of the experimentals and 42% of 

the controls returned to breed in the same 

location a year later (P = 0.067, df = 1, P > 

0.05). Females in the two groups had equal 

levels of reproductive success as measured by 

number of pups produced and number of pups 

weaned successfully. The foraging period at se,a 
of experimental females (mean = 71 days) was 

not significantly different from that of controls 

(mean = 73.4 6.6 days, N = 28). 

CONCLUSIONS 

We conclude that these experimental 

operations had little discernible effect on the 

survival of pups and adult females and on the 

subsequent breeding behavior of adult females. 

Similarly, no effects on the subsequent behavior 

of yearlings and adult males drugged for 

attachment of diving recorders were noted. As 

a final note, 74 of 77 yearlings translocated fran 

Afio Nuevo in spring or fall to a release point 

within 80 km of the island (after being drugged, 

subjected to diving instrument attachment, 

weighed and held overnight at the Long Marine 

Laboratory) returned to the capture site or 

nearby within seven days. 

These data show that healthy elephant 

seal pups can be brought to the laboratory 

shortly after weaning from March to May (the 

time when the majority of elephant seals are 

stranded (Seagars et al. 1986), subjected to 

treatments and detainment similar to that 

experienced during the rehabilitation process, 

and held for up to twelve days, and then returned 

to their habitat with no ill effects. Do pups of 

the same age that strand fare equally well? Data 

are accumulating from elephant seal pups 

recovered, brought to good health, tagged and 

released by the Marine Mammal Center 

(Sausalito, CA). During the years 1977- 1987, 

183 northern elephant seal pups percentage of 

resights is significantly less thanthe survival rate 

of weanlings to one year, which is 45%. 

Unfortunately, these data are not directly 

comparable with those of the experiment 

presented. However, it would be possible to 

release stranded animals at the rehabilitated for 

2-6 months (generally from March to August) 

were released '. In the next 3.25 years, 19.1% 

were resighted alive, with most of the resights 

within two months of release at Farallon Island, 

during various stages of lactation, adult females 

showed no long-term effects of the experience. 

the rookery nearest the release site at Point 

Reyes peninsula. This same place and at the 

same time of year as experimental animals, and 

in effect, conduct a controlled study. 

These data, and the few successful 

reintroductions of monk seals (Monachus 

nzonachus and M shauinslandi) (Gilmartin and 

Gerrodette 1986, Gerrodette and Gilmartin 1990, 

~eijnders et al. this report), harbor seals (Phoca 

vitulina) (Seagars 1988, Reijnders et al. this 

volume), bottlenose dolphins (Tursiops 

truncatus) (Bassos et al. 1991) and manatees 

(Trichechus nzanatus) (Sirenia Project 199 1 ), 

suggest that marine mammals may be easier to 

reintroduce successfully to their habitat than 

other animals such as birds, terrestrial carnivores 

and primates. 
LITERATURE CITED 

Bassos, M.K., R.S. Wells, and K.S. Norris. 1991. Assessment of the readaptation to the wild of two 

young male bottlenose dolphins after two years in captivity. gh Biennial Conference on the 

Biology of Marine Mammals. Dec. 5-10, Chicago, 11. (abstract only) 

Costa, D.P., B.J. Le Boeuf, A.C. Huntley and C.L. Ortiz. 1986. The energetics of lactation in the 

northern elephant seal. J. Zool., Lond. 209: 21-33. 

Gerrodette, T. and W.G. Gilmartin. 1990. Demographic consequences of changed pupping and 

hauling sites of the Hawaiian monk seal. Conserv. Biol. 4: 423-430. 

Gilmartin, W.G. and T. Gerrodette. 1986. Hawaiian monk seal populations status and recovery 

potential at Kure Atoll. NMFS, Southwest Fisheries Center Admin Rep. H-86-6-16. 26 p. 

Hamilton, L.L., P.J. Zwank and G.H. Olsen. 1988. Movements and survival of released rehabilitated 

hawks. J. Raptor Res. 22: 22-26. 

Le Boeuf, B.J., D.P. Costa, A.C. Huntley and S.D. Feldkamp. 1988. Continuous, deep diving in 

female northern elephant seals, Mirounga a~zgustirostris. Can. J. Zool. 66: 446-458. 

Le Boeuf, B. J., D.P. Costa, A.C. Huntley, G.L. Kooyman and R.W. Davis. 1986. Pattern and depth of 

dives in northern elephant seals, Mirounga a~zgustirostris. J. Zool., Lond. 208A: 1-7. 

Le Boeuf, B.J., Y. Naito, A.C. Huntley and T. Asaga. 1989. Prolonged, continuous deep-diving by 

northern elephant seals. Can. J. 2001. 67: 25 14-25 19. 

Martell, M., P. Redig, J. Nibe and G. Buhl. 1991. Survival and movements of released rehabilitated 

bald eagles. J. Raptor Res. 25: 72-78. 

Seagars, D.J., J.H. Lecky, J.J. Slawson, and H.S. Stone. 1986. Evaluation of the California marine 

mammal stranding network as a management tool based on records for 1983 and 1984. 

NMFS, Southwest Fisheries Center Admin. Rept. SWR-86-5, 34 p. 

Seagars, D.J. 1988. The fate of released rehabilitated pinnipeds based on tag-resight information: a 

preliminary assessment. NMFS, Southwest Fisheries Center Admin. Rept. SWR-88-1. 3 1 p. 

Servheen, C. and W. English. 1979. Movements of rehabilitated bald eagles and proposed seasonal 

movement patterns of bald eagles in the Pacific Northwest. J. Raptor Res. 13: 79-88. 

Sirenia Project. 199 1. Progress report - tracking of rehabilitated manatees released on the east coast of 

Florida. US Fish and Wildlife Service, National Ecology Research Center, Gainsville FL. 17 

P. 

FOOTNOTE 

C. Gavette, J. Roletto and K. Hanni, Marine Mammal Center, Sausalito CA. 
THE RELEASE OF SEALS FROM CAPTIVE BREEDING 

AND REHABILITATION PROGRAMS: 

A USEFUL CONSERVATION MANAGEMENT TOOL? 

Peter J.H. Reijnders, Sophie M.J.M. Brasseur and Edith H. Ries 

Department of Aquatic Ecology 

Institute for Forestry and Nature Research 

Den Burg, 'The Netherlands 

INTRODUCTION 

The general approach to managing 

endangered and threatened species is strict 

protection of habitat. However, additional 

measures might be necessary in situations wkre 

either the size of the population has declined 

below a critical number or when external threats 

are difficult to control. Under these conditions, 

releasing rehabilitated and captive-bred animals 

might be considered, to bridge a critical period 

of population recovery. 

The benefits of releasing captive-born or 

rehabilitated animals can be offset by the risks 

inherent in this effort. The possible introduction 

of pathogens and interference with the selection 

processes that regulate population size and 

fitness are factors that apply to terrestrial animak 

;is well as marine mammals (Miller, Montali md 

Hush, this report). 

For non-threatened populations, rehabilitating injured or diseased animals is more an 

issue of animal welfare than of conservation and 

management. The objective is clearly to assist 

the individual animal, rather than a population. 

Consequently, the risks and benefits involved 

should be evaluated differently. 

This paper presents our observations on 

the adaptability and survivorship of rehablitated 

harbor (Phoca vitulina) and Mediterranean monk 

(Monachus monachus) seals released to the wild, 

and considers whether such individuals can 

contribute to the population. Three distinct 

approaches, differing by species, origin of animals, and post-release monitoring, are discussed 

CASE STUDIES 

Harbor seals in the Wadden Sea 

Stemming from the concern that the 

harbor seal population in the Wadden Sea has 

decreased significantly during this century 

(Reijnders 1992), captive breeding, rescue, 

rehabilitation and release programs were instituted to support the small numbers remaining 

(Reijnders 1983). To determine the outcome of 

these operations, we evaluated the movements 

and survivorship of reintroduced seals from 

returns of flipper tags fitted on each of the released animals. Data from a separate study on 

tag recoveries from frek-ranging seals were used 

for comparison. 

Dispersal 

Since 1973, nearly all animals released 

in the Wadden Sea have been juveniles. It is 

known that young seals can disperse widely, 

some travelling distances of over 6000 km 

(Peterson et al. 1968, King 1983), a behavior 

known as "removal migration" (Baker 1978). 

Tag recoveries from released and feral seals 

show a similar pattern in both the proportion of 
returns and their distribution (Figs. 1 and 2). seals had the lowest percentage return. 

The majority of seals stay within 100 km of the A temporal analysis of tag-returns over release site; in fact approximately one third of a1 time shows that most recoveries were obtained recoveries have been obtained within 25 km. within the first two years after release (Fig. 4). 

Survival 

Assuming that the probability of recovering a tagged seal is the same for released and 

wild animals, the percentage of tag-returns can 

be considered a relative indicator of the survival 

of each group. Tag returns from stranded seals 

during the first five years after release were 

examined in five groups (Fig. 3): 

Again, the percentage recoveries are the lowest 

in rehabilitated seals and tk highest for animals 

born in captivity and released as subadults, 

indicating higher survival in the former. 

The conclusion is that rehabilitated 

animals and captive-born seals released as 

juveniles adapted well to their environment, 

whereas captive born animals released as 

subadults do not fare as well. 

1) wild - captured, tagged and released (n=18) - - 

2) bred 1 - born in captivity and released as SignzJicance to the Population 

subadults (n=13) The impact of the captive breeding and 

3) bred 2 - born in captivity and released as 

juveniles (n=16) 

4) rehabilitated 1 - born in the wild, rehabiitated 

and released (n=27); excluding those 

classified as "rehabilitated 2" 

5) rehabilitated 2 - born in the wild, rehabiitated 

and released during the same time of year as the 

"bred 2" group (n=52). 

Since the two groups of "bred" seals 

differed not only in the age of the animals at the 

time of release, but also in the time of year that 

they were released, the tag returns for the "bred 

rehabilitation program on the free-rangingpopulation was evaluated using data from aerial 

surveys. Calculations of population size indicak. 

that the number of seals in the Wadden Sea 

would have declined without the contributions 

from immigration and the release program (Fig. 

5). The decrease noted in the mid- 1970s would 

have been more profound, and the recovery 

during the early 1980s only half of what was 

observed. Released animals compensated at 

least in part for the low productivity in this 

population (Reijnders 1983). 

Harbor seals in the Oosterschelde 

2" group were compared with those for rehabili- Harbor seals were historically abundant 

tated seals released at the same time ("rehabili- in the Oosterschelde (S.W. Netherlands). 

tated 2"). No significant difference was found Overhunting, followed by habitat destruction, 

(Fisher's exact test, P>0.8). Since the tag return has reduced the population to the point where 

rates of the two rehabilitated groups were similar, it was concluded that the timing of release 

did not influence survivorship. 

Statistical comparison of the findings 

from the "bred-2" animals with those from the 

"wild", "bred- 1 ", and "rehabilitated- 1 " seals 

revealed no significant difference (Fish's exact 

test, p0.5). There was a tendency for greater 

tag-return from captive-born seals released as 

subadults ("bred- 1), whereas "rehabilitated- 1 " 

. . 

only some 15 seals are observed there each year 

(Reijnders 1985, Reijnders et al. 1990). Hunting 

has been banned since 1962, and the quality of 

the habitat has improved since the heavily polluted waters of the Rhine River were diverted 

from the area. Efforts to recolonize the region 

have begun, particularly since the morbillivirus 

epizootic of 1988 slowed the immigration of 

young seals from the Wadden Sea. 
Three juveniles and two 5-6 year old 

seals, rehabilitated for 3 to 5 months and fitted 

with VFIF-radiotransmitters, were released in the 

spring of 1989. The transmitters were glued to 

the fur, and were expected to fall off during the 

tnoult in June or July of the same year. The 

seals' activities were recorded by an automatic 

registration system, manual tracking and direct 

observations. The animals apparently began to 

feed after a few days. Withill two weeks, diurnal 

and nocturnal haulout patterns were similar to 

those of the free-ranging seals. Four of d~e seals 

stayed in the area that season, and three were 

resighted throughout 1990. Two of the tagged 

animals joined a group of four wild seals and 

interacted with them normally (Reijnders et al. 

1990). Their reactions to human disturbances 

were similar as well, showing that handling in 

captivity had not diminished their wariness 

towards humans. The reintroduction attempt 

was considered successful, and will be continued 

in an attempt to repopulate the improved habitat 

of the Oosterschelde. 

Monk Seals in Greece 

The Mediterranean monk seal is highly 

endangered (Reijnders et al. 1988). A stranding 

alert and rescue network, established in Greek 

waters to help avert extinction of the species 

(Reijnders 1984, Reijnders et al. 1986), retrieved 

two orphaned monk seal pups and brought them 

to the Seal Rehabilitation and Research Centre 

(SRRC) in Pieterburen, The Netherlands. After 

successful rehabilitation over a seven month 

period ('t Hart and Vedder 1990), the seals were 

released in "Northern Sporades", a marine park 

inhabited by monk seals where some protection 

could. be afforded (Reijnders & Ries 1989). 

VHF-radiotransmitters were glued to the fur on 

the top of the seals' heads and were expected to 

fall off during moult in that same year. The 

movements of the animals were monitored for 

several months by an automatic recording staticn 

and mobile tracking units operated from air, sea 

and land. The animals remained within 50 km 

of where they were released. Within a short 

period, their activity pattern changed from the 

daytime feeding schedule in captivity to a predominately nocturnal routine. 

Their readaptation to the wild can also 

be judged from data on diving behavior of one of 

the animals. During the first two weeks after 

release, almost 90% of its dives were shorter 

than 120 seconds (s) and no dive exceeded 240 

s. After about two months, approximately 50% 

of the dives exceeded 240 s and only 30% were 

less than 120 s (Fig.6). The duration of the 

longest dives also changed significantly. The 

average of the ten longest dives increased from 

207 s after release to 345 s hvo months later 

(Student t-test, p<0.001). A comparable change 

was observed in a young, wild harbor seal (E. 

Ries and P. Paffen, unpub. data). The average 

of the five longest dives of this juvenile increased nearly two fold between 6 weeks and 3 

months of age, whereas no difference was found 

in subadults and adults in the same period of that 

year. These changes indicate increased underwater exploration and exploitation of the habitzt, 

possibly related to increased diving capacity. 

Increased dive times might also reflect low prey 

density. 

The results of this first attempt are 

promising, and an expanded program could play 

a significant role in attempts to safeguard this 

species. At present, an emergency rescue and 

rehabilitation centre has been established on the 

island of Alonissos (Northern Sporades, Greece), 

where another monk seal pup was succesfully 

rehabilitated (Visser 1991). 

CONCLUSIONS 

We conclude that captive-bred and 

rehabilitated seals can be successfully reintroduced into their natural environment. Tagrecoveries and radiotelemetry studies demonstrate that survival of the released animals was 

similar to that of free-ranging seals of the same 

species. After several weeks in the wild, seals 

show normal activity patterns and disperse as 
expected within their habitat. Rehabilitated seal; 

appear to adapt most readily, followed by 

captive-born animals released as juwniles; seals 

born in captivity and released as adults appear 

not to fare as well. Programs designed to breed 

seals in captivity for subsequent release should 

deliver the pups to the wild as soon as they are 

self sufficient. 

These conclusions should not be interpreted as advocating captive breeding or rehabilitation programs as the solution to declining wikl 

populations. This approach addresses only a 

symptom, and not the cause, of threats to the 

survival of a species, and can divert attention 

from efforts to determine the 

nature of the underlying threats. Each case 

needs to be evaluated separately, with due 

consideration of the potential risks as well as the 

benefits to the wild population. Until all the 

dangers are identified and investigated, a cautious approach to rehabilitation and release 

programs is recommended. At present, the only 

possible exception is the highly endangered 

monk seal, for which many urgent steps must be 

taken to save it from extinction. 
LITERATURE CITED 

Baker, R.R. 1978. The evolutionary ecology of animal migration. Hoder & Stoughton, Toronto. 1012 

P. 

King, J.E. 1983. Seals of the world. British Museum of Natural History & Oxford University Press. 

240 p. 

Peterson, R.S., B.J. Le Boeuf and R.L. DeLong. 1968. Fur seals from the Bering Sea breeding in 

California. Nature 2 19: 899-90 1. 

Reijnders, P.J.H. 1983. The effect of seal hunting in Germany on the further existence of a harbour 

seal population in the Dutch Wadden Sea. Z. Saugetierk. 48: 50-54. 

Reijnders, P.J.H. and J.H. Prime. 1984. The importance of a breeding unit and nursery station for 

Mediterranean monk seals in respect to their conservation: outline programme, p. 21-29 In J. 

Hanvood, S.S. Anderson & J.H. Prime [eds.] Special measures for the conservation of monk 

seals in the European Community. Report EUR. 9928 ENV. Commission for the European 

Communities,. 

Reijnders, P.J.H. 1985. On the extinction of the southern Dutch harbour seal population. Biol. 

Conserv. 3 1 : 75-84. 

Reijnders, P.J.H. 1992. Retrospective population analyses and related future management perspectives for the harbour seal Phoca vitulina in the Wadden Sea. In N. Dankers, C.J. Smit & 

M.Schol1 [eds.] Proceedings of the 7th International Wadden Sea Symposium, Ameland, The 

Netherlands, 22-26 October 1990. Neth. Inst. Sea Res., Publ. Ser. 20: 193-197. 

Reijnders, P.J.H., A. Econonmou, S. Spiropoulou and R. Beudels. 1986. Information and rescue 

system for the monk seals in the European Community: a pilot scheme for its establishment in 

Greece. Report to the European Commission, Brussels. Research Institute for Nature 

Management, Texel (NL). 7p. 

Reijnders, P.J.H., M.N. de Visscher and E.H. Ries. 1988. The Mediterranean monk seal. 

IUCNRJNEP, Gland, Switzerland. 59 p. 

Reijnders, P.J.H. and E.H. Ries. 1989. Release and radiotracking of two rehabilitated monk seals in 

the marine park "Northern Sporades", Greece. Report presented to the European Commission 

and International Fund for Animal Welfare. Research Institute for Nature Management, Texel 

(NL). 17 p. 

Reijnders, P.J.H., I.M. Traut and E.H. Ries. 1990. Verkennend onderzoek naar de mogelijkheden voor 

het terugzetten van gerevalideerde zeehonden, Phoca vitulina, in de Oosterschelde. RINreport 90110. Research Institute for Nature Management, Texel (NL). 36 p. 

't Hart, L. and E.J. Vedder. 1990. The rehabilitation of two newborn Mediterranean monk seals 

Monachus monachus in the Seal Rehabilitation and Research Centre (SRRC) in Pieterburen, 

The Netherlands, SRRC, January 1990. 17 p. 

Visser, 1. 1991. The rehabilitation of an orphaned Mediterranean monk seal Monachus monachus in 

the National Marine Park of the Northern Sporades, Greece. Seal Rehabilitation and Research 

Centre, Pieterburen (NL) and the Hellenic Society for the Study and Protection of the Monk 

Seal, Athens (Gr). 3 1 p. 
FIGURE LEGENDS 

Fig. 1. Distribution of juvenild harbor seals in different areas of the Wadden sea. 

Fig.2. Percentage of tag-recoveries of juvenile harbor seals in relation to distance covered. 

Fig.3. Percentage tag-recoveries of seals, five years after their release. See text for description of 

groups. 

Fig.4. Percentage tag-recoveries of seals, followed over the first five years after their release. 

Fig.5. Counts of harbor seals in the Dutch Wadden Sea based on aerial surveys, and estimated 

numbers if no immigration and no release had occured. 

Fig.6. Diving time distribution of a monk seal during three periods after its release, based on periods 

lasting 6 to 8 hours. 
tagging centre recoveries 

rn - H Niedersachsen 

--- Schleswig Holstein 

0- o The Netherlands *- * The Netherlands 

A- A Denmark 

NORTH SEA 

The Netherlands 

Fig. 1. Distribution of juvenile harbor seals in 

different areas of the Wadden Sea. 
- + - Wild (n=34) 

-m- Rehabilitated (n=48) 

0 200 400 600 800 1000 

DISTANCE (km) 

Fig. 2. Percentage of tag-returns from juvenile harbor seals 

in relation to distance from the release site. 
Wi Id Bred I Bred 2 Rehab. 1 Rehab. 2 

GROUP 

Fig. 3. Percentage of tag-returns for juvenile harbor seals, 

five years after their release. See text for description 

of groups. 
u u a Y E 

a a Ea, Q) 

uu 

U) w w 

- + U) ([I ([I 

Q) + w 3 - .- .- 

.- - - 

u 

([I c E E 

a - 2 >" T T ([I ([I 

=I 

U) 3 .z E 2 
Aerial Survey 

Counts 

Estimate 

Without 

Immigration 

Estimate Without 

Release or 

lmmigration 

00 

1970 1972 1974 1976 1978 

, 

1980 1982 

I I I - 

1984 1986 

YEAR 

Fig. 5. Counts of harbor seals in the Dutch Wadden Sea based on 

aerial surveys, and estimated numbers if no immigration 

and no release had occured. 
DIVE TIME DISTRIBUTION 

5/5/88 6/22/88 6/27/88 

DATA PERIOD 

Fig. 6. Distribution of dive times of a monk seal during 

three 6-8 hour periods after release.