Return-path: <WHE_WILLIAM@flo.org> Received: from flo.org by VMSVAX.SIMMONS.EDU (PMDF V4.3-10 #8767) id <01HK2AV4IL2O005SBD@VMSVAX.SIMMONS.EDU>; Tue, 29 Nov 1994 19:54:41 -0500 (EST) Date: Tue, 29 Nov 1994 20:00:53 -0500 (EST) From: Michael Williamson <WHE_WILLIAM@flo.org> Subject: Case Study: Dolphin release To: whalenet@VMSVAX.SIMMONS.EDU Message-id: <email@example.com> Content-transfer-encoding: 7BIT From: SMTP%"MARMAM@UVVM.BITNET" 29-NOV-1994 17:51:31.49 To: WHE_WILLIAM CC: Subj: Considerations for Captive Release Date: Mon, 28 Nov 1994 17:49:59 -0800 Reply-To: Marine Mammals Research and Conservation Discussion <MARMAM@UVVM.BITNET> Sender: Marine Mammals Research and Conservation Discussion <MARMAM@UVVM.BITNET> Comments: Warning -- original Sender: tag was rbaird@SOL.UVIC.CA From: firstname.lastname@example.org Subject: Considerations for Captive Release X-To: email@example.com To: Multiple recipients of list MARMAM <MARMAM@UVVM.BITNET> Considerations for Captive Release Don Croll, Bernie Tershy, and Kevin Starr firstname.lastname@example.org and email@example.com Recently there has been a flurry of discussion and debate regarding the arrival at UC Santa Cruz Long Marine Laboratory of two bottlenose dolphins from the U.S. Navy dolphin program. It has been suggested that these animals belong in the wild, not in captivity in a cement pool and that they should be released rather than held for research. Indeed, a program for the release of dolphins used in Navy programs has been initiated by a group in Florida. The hope is to reprogram these highly trained animals so that they may again function as wild dolphins - able to forage for themselves and engage in the kin-based social organization of the wild population. We do not know the details of this program, nor do we wish to suggest that the individuals undertaking the project are not doing the best job possible. We also do not intend to suggest that captive released animals cannot incorporate into the social organization of a wild group of animals. The wild reintroduction of once captive animals is a difficult task, and one that should be approached with much careful planning, rigor, and methods for monitoring success well into the future. However, our reasons for writing extend beyond this issue. Emotions surrounding the morality and ethical use of wild animals held in captivity inevitably run high. The debate regarding the release of captive animals into the wild is not new. It is probably fair to say that discussions surrounding release juxtapose the benefits to the captive animals of wild release with the long-term benefits of perpetuating their captivity. Both sides often attempt to take a moral higher ground - one side proclaiming that such use of wild animals is unethical and that these animals should be released back to the wild, the other side taking a righteous stand on the educational or research value of wild species held in captivity. Sick, stranded, oiled, or otherwise incapacitated individuals from the wild (particularly of those species our society has designated as charismatic -otters, seals, dolphins, etc.) are also held in rehabilitation centers for variable periods and released to the wild. We do not intend to take sides in discussions of the use of wild animals for research and education or the rehabilitation of incapacitated wild animals. We do, however, wish to give voice to a group that is seldom considered: the wild population of animals into which the captive animal is released. More specifically, we hope to ask whether the release of captive-held individuals is in the best interests of wild populations and global biodiversity. Captive animals released into the wild can impact wild populations in three ways: 1) competition for limited resources such as food, shelter, water or mates; 2) deleterious outbreeding-dilution or contamination of locally adapted genomes; and 3) introduction of diseases which do not naturally occur in the wild population. Here we would like to focus on the potential introduction of non-native diseases, and briefly discuss the more obvious potential for deleterious outbreeding. This notion of disease spread may sound alarmist, but the possibility is real. Most animals are held in captivity in a confined area where many individuals and perhaps species of wild animal are in close proximity (e.g. zoos, aquaria, or rehabilitation centers). In spite of variable amounts of time and care taken in the isolation and quarantine of individuals or species, the risk of disease cross infection in such centers can be significant. Introduced diseases may be directly transferred from one individual of a species to another, or it may be transferred from one individual of a species to an entirely different species. If captive-held individuals were held in captivity in perpetuity, then disease transfers would only be a concern for animal husbandry and not for the conservation of populations and biodiversity. However, when individuals held in captivity (for whatever reason) are released into the wild, diseases may be released with them. To our knowledge, captive to wild disease transfers have not been documented in marine mammals (to a large extent, this may be due to the difficulty of studying the presence and origin of diseases in wild marine mammals and the spread of disease in marine animals). We offer several examples of disease transfer from captive held terrestrial animals to wild populations which may illustrate that disease transfer is a real threat: The golden lion tamarin is a small primate which has lost much of its Atlantic rainforest habitat in Brazil. Because of this it is endangered with only a few remnant wild populations. Captive breeding programs for golden lion tamarins were initiated, and releases were about to occur in an effort to enhance the wild population numbers. Just before the scheduled release, the captive individuals started to die in significant numbers from a viral disease, callitrichid hepatitis, which originated in captivity. This virus causes high mortality, and if introduced into the wild, it would have pushed the species closer to extinction. Another similar captive breeding program for orangutans almost led to the release of tuberculosis to the wild orangutan population as well as introducing the disease to the local human population. Another example of the possible damage of captive animal release to native populations can be found with the desert tortoise in Southern California. The recovery of this endangered population has been hampered by problems with habitat destruction and the introduction of an upper respiratory tract disease which originated in tortoises held in captivity as pets and subsequently released into the wild. More examples of disease introductions and near introductions exist in a myriad of species: heath hens, black-footed ferrets, whooping cranes, Mauritius pink pigeons, Aral Sea sturgeon, rainbow trout, Hawaiian crows, Arabian oryx... We would argue that captive breeding programs which aim to enhance the number of individuals of a highly endangered population (for example the California Condor) can be worthwhile. These populations have few options for perpetuating themselves and the possible benefits of enhancing the number of individuals may be worth the risk of spreading disease to the wild population. In addition, such programs are generally careful with the potential for disease transmission to the endangered population. We would also argue that release of captive animals to the wild may not be worth the risk for less endangered or threatened populations where introduced diseases could become pandemic. In other words, it is important that an analysis of the benefit to the wild population versus the potential cost be undertaken before captive release occurs. Captive release also brings with it the possibility of human induced changes in the gene pools of wild populations. This can occur when individuals from populations native to one area are released to areas where they would not normally occur. This is of particular concern when the same "species" of marine mammal exists in separation in two ocean basins. Such releases would likely have a low probability of significantly altering wild gene pools. However, a risk of introducing potentially deleterious gene combinations into the wild population exists. In addition, such introductions (if the released animals eventually breed) will change gene combinations in the wild population and may alter evolutionary patterns in ways we are not able to measure. Perhaps with great care and analysis, the risks of captive release to wild populations can be minimized. However, we believe that the burden of proof (of no harm to wild populations) should be placed on those individuals planning to release or re- release animals into the wild. At present such analyses are not always undertaken. We may also argue that the taking of wild animals for captive uses should also be carefully considered, but do not wish to address this issue here. As biologists, our intention is to examine the controversy surrounding the release of captive marine mammals from a population perspective. First and foremost, we believe that the impacts and benefits of the release should be examined from the viewpoint of the wild population. Until such analyses occur, we run the risk of doing damage to populations in the hope of helping the individual.