by Randall L. Brill NCCOSC RDTE DIV 511 San Diego, California

[The following article was originally presented at the 1994 AZA Conference in Atlanta, Georgia. It is reprinted here with the kind permission of the author and the American Zoo and Aquarium Association.]

Professionals responsible for the management of Atlantic bottlenose dolphins (Tursiops truncatus) have been addressing the pros and cons of returning long-term captive animals to the wild. Campaigns calling for the release of dolphins from public display and research facilities conducted by animals rights activists have gained notice. They base their arguments in favor of such a strategy on only one premise - captivity, of any kind, is bad, therefore, dolphins should be set free (see Jenkins, 1993; Joseph, 1993). Professionals (e.g.: scientists, trainers, managers, etc.), on the other hand, recognize the need to determine the risks and benefits of such action and insist on identifying responsible biological justifications before taking it (see Brill and Friedl, 1993). In light of the biological implications of the term "reintroduction," this paper represents the reintroduction program that has yet to be - more importantly, it addresses the question of whether it should be.

In the world of conservation biology, "reintroduction" is recognized as a technique which uses wild-bom and/or captive animals to establish or replenish wild populations in natural habitats from which the species has been extirpated by nature or man ( Stanley Price, 1991). The issue of note is that this technique is intended to benefit populations of endangered species in the wild, not individuals of surplus or unwanted captive stocks. The Atlantic bottlenose dolphin is not an endangered species. Under a clearly recognized exemption legislated in the Marine Mammal Protection Act and reauthorized by Congress, the dolphins cared for in public display and research facilities in the United States were collected or bred without any intention of being returned to the wild. Furthermore, their interactions with humans, more so than most animals in zoological environments, are frequent, and reinforced through behavioral modification.

Many, including this author, have previously misused the term "reintroduction" to refer to putting Atlantic bottlenose dolphins long accustomed to human care back into the ocean. It is more appropriate, with regard to these animals, to use the phrase "return to the wild," defined as a well planned, executed, and documented scientific process, similar to reintroduction, the ultimate goal of which is to release dolphins into a wild population for the purpose of their resuming a life free of any further intervention by or dependence upon humans. The process should yield biological benefits to the host population as well as to the animals returned. it should be noted that such a process conducted with dolphins that have become accustomed to, if not dependent upon, human care, presents a case much different from that of wild marine mammals that have stranded, been rehabilitated, and finally released (Geraci and St. Aubin, 1991). The question at hand, then, is for what reason, if any, should long-term captive marine mammals of a non-endangered species be returned to the wild?

Individuals referring to themselves as "dolphin release activists" claim a number of successes at releasing dolphins in the wild. Unfortunately, the details of these efforts are not documented in peer reviewed publications, if at all. Three examples are frequently cited by activists.

1. Joe and Rosie, Atlantic bottlenose dolphins previously involved in research, were acclimated in the Florida Keys, and were released off the coast of Georgia. The dolphins were tracked for two months afterward, resulting in a total of eight confirmed sightings (Anon., 1988). Whether the dolphins were ever actually sighted again is unclear. This project at least demonstrated concern for the dolphin population and potential environmental impact at the release site as well as efforts to modify the dolphins' behavior prior to release.

   The "Into the Blue" project (McKenna, 1992), involved three dolphins (1.1 Atlantic and 0.1 Pacific bottlenose dolphins [Tursiops truncatus gilli]) previously maintained in British oceanaria. The animals were released near the Turks and Caicos Islands. Reports of post-release sightings by local fishernen lack credibility, leaving the fate of the dolphins unconfirmed. The intentional permanent release of animals far from their home ranges, particularly a Pacific bottlenose dolphin in the Atlantic Ocean, are cause for serious criticism of the planning for and motives behind this effort.

The only known photograph of any of the three dolphins released in the Turks & Caicos Islands by the Into the Blue project was taken in September 1991, less than two weeks after the release. This photograph of Silver, a male Pacific bottlenose dolphin, shows a noticeably emaciated dolphin with the shoulder bone of the right pectoral fin clearly visible.

 

The release of a dolphin named 'Flipper' in Brazil has, for over a year now, generated reports of the animal being observed bearing injuries caused by either fishing nets or aggressive dolphins, appearing at beaches to interact with and accept food from bathers, and frequently observed in the company of a group of tucuxi dolphins (Sotalia fluviatilis) (see Rollo, 1994; WSPA, 1994). This project demonstrated attention to pre-release preparations and post-release monitoring. However, its outcome clearly begs the question of whether a dolphin that seeks human interaction and the company of another species rather than conspecifics was adequately prepared to resume life in the wild.

While these efforts have provided varying levels of documentation via privately published reports or accounts in the media and popular press, they are reported in a subjective manner and offer little in the way of satisfying, quantifiable data. If one defines "release" as the act of placing an unrestrained animal in a wild habitat for the purpose of preventing its keeping in a man-made facility, then the activists have valid claims to success. If, on the other hand, one seeks to provide a process, a return to the wild, which benefits the dolphins released, the populations and ecosystems that host them, and future efforts of its kind, then only two efforts have provided valid approximations to date.

1. Randall Wells collected 2.0 juvenile Atlantic bottlenose dolphins inTampa Bay, Florida. The dolphins were taken to the Long Marine Laboratory at the University of California in Santa Cruz to participate in biosonar studies. Two years later, they were successfully returned to Tampa Bay and rejoined the indigenous population (Wells, 1989;Bassos, Wells, and Norris 1991; Bassos, 1993). Confirmed sightings of both dolphins continue to be documented (Bassos, pers. comm.). The careful planning, execution, and ongoing documentation of this project clearly establish its validity and success. However, the Wells' project must be cautiously viewed as unique. The fact that a brief period of human care and a return to the wild were a part of the plan from the outset make it difficult to draw direct parallels between it and similar efforts that may be undertaken with dolphins much more accustomed to human care. It nevertheless stands as a significant contribution to any future efforts to return dolphins to the wild.

   With the closing of the Atlantis Marine Park near Perth, Australia, and unsuccessful efforts to relocate its group of Atlantic bottlenose dolphins to other facilities, Nick Gales headed an effort to return the animals to the wild (Gales and Waples, 1993). The group of nine dolphins released consisted of 3.2 adults originally collected from the Indian Ocean, 0.3 captive-born juveniles, and 0.1 two months of age. Gales' plan included pre-release behavioral studies, assessment of the local offshore dolphin population, behavioral conditioning for foraging, acclimation to an open water environment, periodic health checks, and a nine-month post-release tracking period using freeze brands and radio tags to identify and locate the dolphins. The post-release efforts were plagued with a number of problems including the premature failure of the radio tags. At the end of a month and a half, the calf was assumed lost and three of the dolphins, including the calf's mother, had been recovered with noticeable weight losses. Four unconfirmed sightings of dolphins wearing radio tags were reported over the following two months. The three recovered dolphins were relocated to a commercial aquarium and the disposition of the others is undetermined.

Despite the outcome, the Gales' project represents the first responsibly planned and documented effort to return long-term captive dolphins to the wild. The data and lessons learned provided in its documentation (Gales and Waples, 1993) should be viewed critically and will no doubt be important contributions to future efforts.

In 1992, twenty-eight experts in the fields of conservation biology and marine mammal public display and research attended a Navy-sponsored workshop to evaluate the concept of returning marine mammals to the wild. Their deliberations were based on a hypothetical plan that incorporated nine elements:

• Social Behavior and Natural History
• Animal-Human Interactions
• Nutritional Requirements and Food Stocks
• Species Specific Requirements
• Environmental Requirements and Considerations
• Criteria for Identifying Candidate Animals
• Disease Transmission and Genetics
• Pre-release Training
• Post-release Tracking and Monitoring

Participants worked in groups to evaluate each element, comment on its importance and application, and make recommendations. The participants then convened in a plenary session to compare the groups' findings and conclusions. The results, detailed in a Navy Technical Report (Brill and Friedl, 1993), can be summarized in three questions and their respective answers.

1. Can marine mammals that have been under human care for a significant length of time be successfully returned to the wild? The simple answer is, with responsible preparation and conduct, probably. However, quantifiable success will be dependent upon resources, methods, and technologies that require development; for example, as will be noted further, tracking and telemetry equipment that can withstand the rigors of being attached to a marine mammal living at sea and reliably provide data for an adequate length of time.

   Is returning such animals to the wild appropriate? The workshop participants made a strong statement: "There is no compelling scientific reason for reintroducing nonendangered species" (Brill and Friedl, 1993). A reasonable implication of this statement is that there is no obvious benefit to the animals returned or the population that will host them. To validly determine the appropriateness and identify any biological or scientific benefit, the associated risks must first be identified and then resolved to a minimum, if not eliminated.

   The participants did, however, recognize the potential value of methods and technologies that might be developed with a non-endangered species such as the Atlantic bottlenose dolphin that could be applied to the conservation and management of a species like the Chinese river dolphin (Lipotes vexillifer); in other words, the potential for carryover benefits to an endangered species (see Ames, 1991).

   Finally, what issues should be resolved before attempting the return of such animals to the wild? The working groups had several concerns in common. Among those were the need for effective behavioral modification protocols, the risk of exceeding the carrying capacity of the environment, disruption of the host population's social structure and reproductive patterns, inviting unwanted human intervention, and so on. The more salient concerns included the lack of federal regulatory policies for returning captive marine mammals, the importance of returning animals to their home ranges, the handicapping of the effective prediction and quantification of potential benefits by the insufficiency of current data, and the inability to predict the risk of mortality to the animals returned and the populations that would host them.

The participants identified two issues as specifically requiring resolution prior to any actual attempt to return marine mammals to the wild. First, the inability to understand the potential for disease transmission between returned animals and wild populations and vice versa - while the participants agreed that disease transmission may not necessarily constitute a grave situation, they felt the current state of knowledge did not warrant placing individuals and populations at risk without the benefit of satisfactory predetermination. Second, the inability to track marine mammals at sea for a minimum of one full seasonal cycle after release - the technology for small, unobtrusive telemetry packages that can be comfortably attached to marine mammals and provide a year's worth of data requires development. The participants felt that quantifiable postrelease data were a requirement for defining the justifications, benefits, and any success of conducting a return to the wild.

In summary, the participants of this workshop, marine mammal experts with a diversity of backgrounds, identified critical issues and voiced serious concern for their resolution before attempting to return nonendangered, long-term captive marine mammals to the wild. They did not, however, ignore the possibility that such efforts, conducted responsibly and empirically, could yield scientific and technological contributions. If nothing else, these experts certainly made it clear that returning dolphins to the wild will not be as readily accomplished as activists would have us believe. The responsible management of any population demands, for any action taken on its behalf, an awareness and identification of the associated risks and benefits, followed by the pursuit of effective, reproducible means of reducing the risks and exploiting the benefits for the good of the population.

There are a vast number of issues that need to be taken into account when attempting to return dolphins to the wild. Simply training them to once again eat live fish, for instance, does not mean that the dolphin will know how to find those fish on its own once it has been released.

Based on the findings of the workshop, the Navy's Technical Report ( Brill and Friedl, 1993) offers a generic model for planning efforts to return marine mammals to the wild. The model addresses the issues of concern raised by the workshop participants and promotes the pursuit of basic research and technological development. Overall, the model is designed to be generic and act as a guide to planners who would insert their specific requirements and objectives. Of interest is the fact that, while arrived at quite independently, the workshop findings and resulting model are quite similar to the guidelines and concerns expressed by reintroduction specialists in such documents as IUCN's position statement (IUCN, 1987).

Should those of us engaged in the care of marine mammals for public display and research ignore "return to the wild" as a potential tool for managing our animals? Of course not! It should, however, be weighed against the appropriateness and potential benefits of other options available. The conduct of a valid program for nonendangered marine mammals, even one that may be designed specifically to be experimental (see Lindburg, 1992), is certainly within the realm of possibilities. The definition of "return to the wild" does not obviate the conduct of necessary approximations or limit the potential scenarios that may be employed. However, it would be inadvisable and irresponsible to attempt to return any dolphins to the wild without having first determined that it is the best option for the animals returned and the population that will host them, without having clearly defined the biological purpose and justification, and without addressing risks and exploiting benefits through bona fide research and careful professional management.

Are there foreseeable circumstances that might justify returning Atlantic bottlenose dolphins to the wild? The knee-jerk response of scientists might be that such efforts should be conducted for basic research, the gain of knowledge for the sake of it. The potential payoffs for the conservation and management of endangered species, as alluded to earlier, certainly present potential justifications. Likewise, as problematic as it may seem to some, the contribution of captive stock to locally depleted populations is a consideration, especially in light of the threat of major die-offs, most recently in the Gulf of Mexico.

What about returning dolphins that are surplus to collections or simply because there are activists who would prefer to set them free? Specialists have voiced clear warnings with regard to the use of reintroduction in the management of surplus animals (see Kleiman, 1989). Captive breeding programs for the Atlantic bottlenosedolphin have been successful and are improving consistently (Asper et al., 1990). Relying on returning nonendangered surplus stock to the wild hardly seems to be an appropriate strategy for a responsible captive breeding program. As for the notion of setting animals free, we come full-circle and return to the requirements of identifying the best option available, benefitting the wild population, and conducting such programs responsibly. The "Into the Blue" and "Flipper" releases, as documented on film by the BBC and National Geographic respectively, show interesting parallels. In both cases the dolphins involved hesitated to leave their enclosures for open water and when they did, their first action was to go to nearby humans in the water or on boats. Such responses were certainly not indicative of animals that were seeking the "freedom" of open sea. That leads one to wonder whether if, as it suggests, the animals were not adequately prepared to return to the wild? Was the end result nothing more than to replace one form of captivity with another, physical confinement with behavioral limitations?

The Navy Technical Report (Brill and Friedl, 1993) is not the only statement of concern over returning dolphins to the wild. The report prepared for Canada's Minister of Fisheries and Oceans (Anon., 1992) recognizes that research is necessary to find solutions to potential problems prior to attempting the return of marine mammals. That report concludes that the current state of knowledge is such that "the release to the wild of cetaceans that have been in captivity for extended periods is inappropriate." The professionals involved in the care of marine mammals in public display and research facilities assume that the activists who would have us put our dolphins back into the wild would also like to see them survive. That is at least one aspiration that everyone holds in common. As professionals, we expect and would do no less than whatever is necessary to increase the probability of survival, applicable benefits, and, therefore, success. Literature Cited

Ames, M.H. (1991). Saving some cetaceans may require breeding in captivity. BioScience. 41(l):746-749.

Anon. (1988). A journey home. Oceanic Research Communication Alliance (ORCA), Tides Foundation, San Francisco, California.

Anon. (1992). Capture and maintenance of cetaceans in Canada. A report prepared by the Advisory Committee on Marine Mammals for the Minister of Fisheries and Oceans.

Asper, E.D., D.A. Duffield, N. DimeoEdiger, and D. Shell (1990). Marine mammals in zoos, aquaria, and marine zoological parks in North America: 1990 census report. International Zoo Yearbook. 29:179-187.

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 (Abstract). The Ninth Biennial Conference on the Biology of Marine Mammals, Chicago, Illinois.

Bassos, M.K. (1993). A behavioral assessment of the reintroduction of two bottlenose dolphins. Master's thesis. University of California at Santa Cruz.

Brill, R.L. and W.A. Friedl (1993). Reintroduction to the wild as an option for managing Navy marine mammals: (Technical Report 1549). Naval Command, Control, and ocean Surveillance Center RDT&E Division, San Diego, California 92152-5001.

Gales, N. and K. Waples (1993). The rehabilitation and release of bottlenose dolphins from Atlantis Marine Park, Western Australia. Aquatic Mammals, 19(2):49-59.

Geraci, J.R. and D.J. St. Aubin (1991). Workshop on rescue and release of marine mammals (Meeting agenda). 35 December, 1991. Chicago, Illinois.

IUCN (1987). The IUCN position statement on translocation of living organisms: introductions, reintroductions, and restocking. International Union for the Conservation of Nature (IUCN), Gland, Switzerland.

Jenkins, R.L. (1993). An analysis of marine mammal display problems in the media. In N.F. Hecker (Ed.), Proceedings of the 18th Annual International Marine Animal Trainers Association Conference (1990) (pp. 266-273). Baltimore: De Vilbiss Printers.

Joseph, B. (1993). Marine mammals in zoological environments: current threats, goals, and opportunities. in N.F. Hecker (Ed.), Proceedings of the 18th annual International Marine Animal Trainers Association Conference (1990) (pp. 254-265). Baltimore: De Vilbiss Printers.

Kleiman, D.G. (1989). Reintroduction of captive mammals for conservation. BioScience. 39(3):152-161.

Lindburg, D.G. (1992). Are wildlife reintroductions worth the cost? Zoo Biology. 11:1-2.

McKenna, V. (1992). Into the blue. London: Aquarian Press.

Rollo, M.M. (1994). The last captive dolphin in Brazil: a project of rehabilitation, releasing, and monitoring in the natural environment (Abstract). The Tenth Biennial Conference on the Biology of Marine Mammals. Galveston, Texas.

Stanley Price, M.R. (1991). A review of mammal re-introductions, and the role of the Re-introduction Specialist Group of IUCN/SSC. In J.H.W. Gipps (Ed.). Beyond captive breeding: reintroducing endangered mammals to the wild (pp. 9-25). Oxford: Clarendon. (Symposia of the Zoological Society of London, No. 62).

Wells, R.S. (1989). Return to the wild: completion of a "dolphin sabbatical". Whalewatcher. Winter:3-5.

WSPA (1994). Press release issued by the World Society for the Protection of Animals, 24