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Captivity Studies

Captivity studies

Field Studies | Acoustic Studies | Toxin Studies | Brain Studies

Pulmonary Zygomycosis with Cunninghamella bertholletiae in a Killer Whale (Orcinus orca) Abdo W., et al. (2011).

Orca Behavior and Subsequent Aggression Associated with Oceanarium Confinement Anderson, R, et al. (2016).

Dolphin (Tursiops truncatus) echoic angular discrimination: Effects of objects separation and complexity Branstetter, B. K., et al. (2007).

Cutaneous papillomaviral-like papillomatosis in a killer whale (Keiko) Bossart, et al. (1996).

PROJECT DEEP OPS: Deep Object Recovery with Pilot and Killer Whales Bowers, C.A. and R.S. Henderson, (1972).

Reintroduction to the wild as an option for managing Navy Marine Mammals Brill, R.L. and W.A. Friedl (1993).

Decades-long social memory in bottlenose dolphins Bruck, Jason N. (2013).

In Search of Marine Mammals Claridge, D., K. C. Balcomb (1993).

Killer Whale (Orcinus orca) Reproduction at Sea World Duffield, Deborah A. (1995).

Preliminary report to Jerye Mooney, Fund for the Animals, Re: Keiko-Reino Aventura, Mexico City, Mexico 7/08/93 Cornell, L (1993).

A Review of the Releasability of Long-Term Captive Orcas Garrett, H. (1998).

A Killer Whale’s (Orcinus orca) Response to Visual Media. Hanna, Pepper (2017).

Intelligence and rational behavior in the Bottlenosed Dolphin. Herman, L. M. (2005).

The Bottlenosed Dolphin's (Tursiops truncatus) Understanding of Gestures as Symbolic Representations of its Body Parts. Herman, et al. (2001).

Observations of Disparity Between Educational Material Related to Killer Whales (Orcinus orca) Disseminated by Public Display Institutions and the Scientific Literature Hoyt, et al.(1994).

Bias and Misrepresentation of Science Undermines Productive Discourse on Animal Welfare Policy: A Case Study Jaakkola, Kelly et al. (2020).

Captive killer whale (Orcinus orca) survival Jett, John, Jeff Ventre (2015).

Evidence of Lethal Mosquito Transmitted Viral Disease in Captive Orcinus orca Jett, John, et al.(2012).

The Harmful Effects of Captivity and Chronic Stress on the Well-being of Orcas (Orcinus orca) Marino, Lori, et al.(2019).

Do Zoos and Aquariums Promote Attitude Change in Visitors? A Critical Evaluation of the American Zoo and Aquarium Study Marino, Lori, et al.(2010).

The Captivity Industry - The Reality of Zoos and Aquariums Marino, Lori, et al.(2009).

Summary Report of Evaluation Panel Convened to Assess the Health of Keiko-January 28, 1998 McBain, et al.(1998).

Rehabilitation and release of marine mammals in the United States Moore, Michael, et al. (2007).

Echolocation by killer whales (Orcinus orca) while in pursuit of live fish Newman, K., H. Markowitz (1993).

The dolphin's (Tursiops truncatus) understanding of human gazing and pointing: Knowing what and where. Pack, A. A. & Herman, L. M. (2007).

Mirror self-recognition in the bottlenose dolphin: a case of cognitive convergence Reiss, D., and L. Marino (2001).

From captivity to the wild and back: An attempt to release Keiko the killer whale Simon, M. et al. (2009).

Survival of five species of captive marine mammals Small, R. and D. DeMaster (1995a).

Acclimation to captivity: a quantitive estimate based on survival of bottlenose dolphins and California sea lions Small, R. and D. DeMaster (1995b).

Mission creep in the application of wildlife law: The progressive dilution of legal requirements regarding a wild-born orca kept for ‘research’ purposes Spiegl, M. V., et al. (2019).

Big Star All at Sea Valentry, Duane (1969).

Experimental return to the wild of two bottlenose dolphins Wells, R. S., et al. (1999).

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Abdo, W., Y. Kakizoe, M. Ryono, S. R. Dover, H. Fukushi, H. Okuda, R. Kano, T. Shibahara, E. Okada, H. Sakai and T. Yanai, (2012). Pulmonary Zygomycosis with Cunninghamella bertholletiae in a Killer Whale (Orcinus orca). J. Comp. Path. 2012, Vol. 147, 94e99.

Summary: An adult female killer whale (Orcinus orca) was transported to the Port of Nagoya public aquarium in June 2010. While the animal was being maintained in the aquarium there was a gradual decrease in body weight. On October 1st, 2010 the whale exhibited signs of gastrointestinal disease and died on January 14th, 2011. At necropsy examination the gastric compartments were filled with a large number of variably-sized rocks (total weight 81.4 kg) and there was marked ulceration in the third compartment. There were multifocal tubercle-like nodules within the lungs and on sectioning there were numerous abscesses and pulmonary cavities. Microscopically, there was severe suppurative pneumonia associated with fungal hyphae that were infrequently septate and often branched. Numerous bacterial colonies were also present. The hyphae demonstrated immunohistochemical cross-reactivity with Rhizomucor spp. and Cunninghamella bertholletiae was cultured. Bacteriological culture revealed the presence of Proteus mirabilis, Pseudomonas aeruginosa and Pseudomonas oryzihabitans. This case represents the first documentation of zygomycosis associated with C. bertholletiae in a marine mammal.
Full paper HERE


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Anderson, Robert, Robyn Waayers and Andrew Knight, (2016). Orca Behavior and Subsequent Aggression Associated with Oceanarium Confinement. Animals 2016, 6, 49; doi:10.3390/ani6080049.

Orca behaviors interacting with humans within apparent friendship bonds are reviewed, and some impediments to the human evaluation of delphinid intelligence are discussed. The subsequent involvement of these orcas and their offspring in aggressive incidents with humans is also documented and examined. This is particularly relevant given that the highest recorded rates of aggressive incidents have occurred among orcas who had previously established unstructured human friendship bonds prior to their inclusion within oceanaria performances. It is concluded that the confinement of orcas within aquaria, and their use in entertainment programs, is morally indefensible, given their high intelligence, complex behaviors, and the apparent adverse effects on orcas of such confinement and use.

Based on neuroanatomical indices such as brain size and encephalization quotient, orcas are among the most intelligent animals on Earth. They display a range of complex behaviors indicative of social intelligence, but these are difficult to study in the open ocean where protective laws may apply, or in captivity, where access is constrained for commercial and safety reasons. From 1979 to 1980, however, we were able to interact with juvenile orcas in an unstructured way at San Diego’s SeaWorld facility. We observed in the animals what appeared to be pranks, tests of trust, limited use of tactical deception, emotional self-control, and empathetic behaviors. Our observations were consistent with those of a former Seaworld trainer, and provide important insights into orca cognition, communication, and social intelligence. However, after being trained as performers within Seaworld’s commercial entertainment program, a number of orcas began to exhibit aggressive behaviors. The orcas who previously established apparent friendships with humans were most affected, although significant aggression also occurred in some of their descendants, and among the orcas they lived with. Such oceanaria confinement and commercial use can no longer be considered ethically defensible, given the current understanding of orcas’ advanced cognitive, social, and communicative capacities, and of their behavioral needs. Full paper HERE

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Branstetter, B. K., Mevissen S. J., Pack, A. A., Herman, L. M., Roberts, S. R., and Carsrud, L. K. (2007). Dolphin (Tursiops truncatus) echoic angular discrimination: Effects of objects separation and complexity. Journal of the Acoustical Society of America, 121, 626-635.

A bottlenose dolphin was tested on its ability to echoically discriminate horizontal angular differences between arrays of vertically oriented air-filled PVC rods. The blindfolded dolphin was required to station in a submerged hoop 2 radial m from the stimuli and indicate if an array with two rods (S+) was to the right or the left of a single rod (S-). The angular separation between the two rods (thetaw) was held constant within each experiment while the angle between the S+ and the S- stimuli (thetab) varied to produce angular differences (Deltatheta=thetab-thetaw) ranging from 0.25 to 4°. In experiment I, thetaw was maintained at 2° and in experiment II, thetaw was maintained at 4°. Resulting 75% correct thresholds (method of constant stimuli) were 1.5 and 0.7°, respectively. The two main findings of this study are: (1) decreasing the number of targets does not aid in localization, and (2) increasing the space between the rods enhances localization. Taken as a whole, the experiments suggest dolphins have a well-developed ability to resolve spatial information through sonar.
Reprint pdfs may be obtained from Brian Branstetter at or from Adam Pack at


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Bossart, G. D., C. Cray, J. L. Solarzano, S. J. Decker, L. H. Cornell, N. H. Altman (1996). Cutaneous papillomaviral-like papillomatosis in a killer whale (Orcinus orca). Marine Mammal Science, Vol. 12:2, p. 274-281.

Quote: "In this report, we document the first case of cutaneous papillomaviral-like papillomatosis in a killer whale. An approximately 10-yr-old male killer whale of Icelandic origin ("Keiko") developed bilateral axillary skin lesions soon after its arrival at a Mexico City oceanarium in 1985." ..."Studies are underway to characterize this presumptive viral disease and to address the potential immunological aspects of its pathogenesis. These studies include evaluation and characterization of the physiological and immunological status of the whale, isolation and characterization of the papilloma-associated virus, and subsequently the design and implementation of potential treatment regimens."

Note: This report is noteworthy because it mentions the word "virus" in the title ("papillovaviral-like") and throughout the paper, and it states that this virus is the "first case" found in a killer whale, strongly suggesting that Keiko was infected with a virus foreign to wild populations, without quite stating clearly that Keiko actually carried any virus. At the time the paper was written many spokespeople for the marine park industry were stating publicly that Keiko should never be released because he carried a contagious virus that could infect wild populations. In 1993, prior to this report, one of its authors, (Cornell), had written a report stating that Keiko's skin problems were the result of environmental stresses and not related to any virus. In 1998, after Bossart, et al.'s report was published, a group of six veterinarians and specialists appointed by the USDA examined Keiko and found him negative for 48 suspected viruses. (See USDA) report, below.) Bossart, et al.'s frightening viral theory was apparently incorrect.


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Bowers, C.A. and R.S. Henderson, (1972). PROJECT DEEP OPS: Deep Object Recovery with Pilot and Killer Whales. NUC TP 306. Undersea Surveillance and Ocean Sciences Department, Naval Undersea Center, San Diego, CA. Unclassified, 86 pp.

Note: Describes in detail the US Navy program from 1968 to 1971 for two male killer whales (Ahab and Ishmael) which were captured in Puget Sound, WA and airlifted to Point Mugu, CA, and later to Kaneohe, HI. Both killer whales were maintained at NUC Hawaii in fenced ocean pens, "...with low maintenance costs and excellent animal health." By September 1970, both whales had attained "open ocean reliability," wherein they would accompany a vessel out to sea an average of five times per week for a round trip distance of 10-12 nautical miles, typically swimming alongside the vessel at speeds of 6-7 knots. Ishmael on 19 February 1971 did not respond to his underwater recall signal and apparently swam away. On 8 June 1971, Ahab went on a 24 hour excursion ranging over 50 nautical miles in a northwesterly direction along the Oahu coast, and no further sea trials were conducted with him. Ahab died in 1974 at an estimated age of 15-16.


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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, San Diego, CA, 92152-5001.

Note: In 1992, as part of a cost-cutting effort, Congress became aware that the US Navy held over fifty "surplus" dolphins. This report documents the results of a study group formed to satisfy a Congressional request to "...develop training procedures which will allow mammals which are no longer required for this project to be released back into their natural habitat..." Instead, the group concluded: "There is no compelling scientific reason for reintroducing nonendangered species. Proven methods of operant conditioning can be used to prepare marine mammals for reintroduction to the wild. The success of reintroducing marine mammals to the wild, however, depends upon resources, methodologies, and technologies which do not currently exist. The success of a Navy reintroduction program would depend on developing technologies for monitoring and tracking reintroduced animals to quantify the success of the effort. Such technology does not exist and its development is estimated to take at least 2 years. In terms of cost effectiveness, the lifetime care and maintenance of the animals is preferable to reintroduction."

Note: The methodologies and technologies for reintroduction did exist (See Mate, 1989a, below) and they were published and available as of the drafting of the Navy report.


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Bruck, Jason N. (2013). Decades-long social memory in bottlenose dolphins. Royal Society Publishing DOI: 10.1098/rspb.2013.1726 Published 7 August 2013.

Long-term social memory is important, because it is an ecologically relevant test of cognitive capacity, it helps us understand which social relationships are remembered and it relates two seemingly disparate disciplines: cognition and sociality. For dolphins, long-term memory for conspecifics could help assess social threats as well as potential social or hunting alliances in a very fluid and complex fission–fusion social system, yet we have no idea how long dolphins can remember each other. Through a playback study conducted within a multi-institution dolphin breeding consortium (where animals are moved between different facilities), recognition of unfamiliar versus familiar signature whistles of former tank mates was assessed. This research shows that dolphins have the potential for lifelong memory for each other regardless of relatedness, sex or duration of association. This is, to my knowledge, the first study to show that social recognition can last for at least 20 years in a non-human species and the first large-scale study to address long-term memory in a cetacean. These results, paired with evidence from elephants and humans, provide suggestive evidence that sociality and cognition could be related, as a good memory is necessary in a fluid social system. Full paper HERE


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Claridge, D., K. C. Balcomb (1993). In Search of Marine Mammals. Bahamas Naturalist, Vol 7:1 p. 11-17.

Note: In addition to a general survey of marine mammals of the northern Bahamas, this article discusses Bahama Mama, an adult female bottlenose dolphin inadvertently released to her assumed native habitat in 1992 after at least seventeen years of captivity. No official followup occurred, however this dolphin was positively photo-identified up to eight months after release in the company of wild dolphins in the Bahamas. This reintroduction, with no preparation, although not an example for future releases, gives reason for confidence in the species' ability to readapt to natural conditions.


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Deborah A. Duffield, Daniel K. Odell, James F. McBain, and Brad Andrews. Killer Whale (Orcinus orca) Reproduction at Sea World. Zoo Biology 14:417-430 (1995).

Sea World has maintained killer whales (Orcinus orca) since 1965. The total killer whale inventory (1965–1993) has included 39 whales (25 females, 14 males); 28 were wild-caught and 11 captive-born, including one second-generation calf. As of September, 1993, there were 19 whales in the breeding program. Ten of these whales (53%) were captive-born, either at Sea World or other facilities in North America. The live wild-caught whales ranged in estimated age from 12–27 years (x¯ ± sd = 17.6 ± 4.2 years). The captive-born whales ranged in age from <1 to 8 years. In the Sea World breeding program (through September, 1993), there have been nine live births and one stillbirth, with eight calves part of the current inventory. Births occurred from July to February. Calving intervals ranged from 32–58 months. Female age at birth of first calves ranged from 8 years to an estimated 17 years (x¯ ± sd = 12.7 ± 3.0 years). Gestation, based on conception estimates from serum progesterone analysis, averaged 17 months (x¯ ± sd = 517 ± 20 days), but successful pregnancies with viable calves occurred from 15–18 months (468–539 days). Females, in the presence and absence of males, were polyestrus with periods of cycling interspersed with individually variable noncycling (presumed anestrous) periods ranging from 3–16 months. Mean serum progesterone levels (±se) were as follows: noncycling periods = 121 ± 20 pg/ml; peak elevations during nonconceptive ovulatory (estrous) cycles = 3,962 ± 2,280 pg/ml; first pregnancies = 14,592 ± 3,854 pg/ml; second pregnancies = 8,389 ± 395 pg/ml; and third pregnancy = 8,180 ± 4,556 .

(page 7)
Females exhibited periods (data not shown) of multiple estrous cycling (polyestrus) interspersed with periods of noncycling (presumed anestrus). The mean interval (rsd) between estrous cycles during polyestrus, measured from one serum progesterone peak elevation to the next, was 43.8 2 2.9 days (N = 50; range: 18-91 days).On average, there were four estrous cycles per polyestrous period, but duration of polyestrus was highly variable, both over time for a given whale and between whales. The number of cycles per period varied from one to 12, the latter polyestrous period spanning 20 months. The length of entervening noncycling periods was also highly variable, lasting on average 7-8 months but ranging from 3-16 months. No synchrony to the timing of polyestrous cycling and noncycling periods among females was observed. Long sustained periods of anestrus were observed in three famales in their 20s, possibly indicating that they were in postestrous condition. The oldest female of the current inventory (>27 years) has exhibited continuous anestrus for the past 6 years. This female perviously had six term pregnancies [Duffield and Miller, 1988], prior to coming to Sea World in January 1987, and cycled at Sea World until mid-1987.

(Pages 11-12)
Periods of polyestrous cycling in the females were initiated in the presence and absence of males. Mating behavior by males was not sufficient to cause noncycling females to enter estrus. Based on daily behavior logs, males demonstrated concentrated courting activity towards a particular female for 5-10 days during what has been shown by examination of urinary reproductive steroid metabolites and gonadotropins to be the time of presumptive ovulation (Robeck et al., 1993.) However, males were observed to copulate not only with females in estrus, but with noncycling (presumed anestrous) and pregnant females as well.
Full article HERE.


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Cornell, L (1993). Preliminary report to Jerye Mooney, Fund for the Animals, Re: Keiko-Reino Aventura, Mexico City, Mexico 7/08/93.

Quote: "This male orca, now about 10 to 12 years of age has been examined by several veterinarians in the past year or so to determine his health status and to establish his value for purchase by their aquariums and marine zoological parks. Keiko has been held in a small pool for these past years, one which could not meet even the meager standards and guidelines of the United States Department of Agriculture (USDA).

"The question now is how long can the whale survive in this facility and where will he go if removed from Mexico City?

"To their credit the owners and curatorial and training staff at Reino Aventura realize the animal is in improper conditions and have repeatedly asked other zoological facilities for their help in relocating him as they have not the money to build him new pools and life support systems as would be needed to secure his future. Until now they have repeatedly been refused in their attempts to sell or relocate him because he suffers from skin conditions which appear to be viral pappilomatous masses at the axillary area on both pectoral fins and another similar lesion on his tail stock anterior to his flukes. If these lesions are indeed viral, and his history would indicate they might be, his contact with other orcas and perhaps other animals of any kind could place those animals in jeopardy of exposure and possibly infection by the same virus(s) until he has been cleared up, assuming this is a virus which is not already endemic in these animals and which is obvious in Keiko because of his environment.

"The results of the clinical blood values and the tissue samples will not be available to us for some days, so for this preliminary report we will evaluate the animal solely on the basis of his history and our examinations, both behaviorally and physically.

"Keiko is, as we have pointed out, a male orca captured in the North Atlantic by Icelandic fishermen in about November of 1983. Judging by his alleged capture size he was about a yearling at that time plus or minus a year.

"After his capture, he was placed in a facility in Canada along with several other orcas and maintained in training as a future show animal until his sale to Reino Aventura in 1985. He is remarkably well adapted to his situation in that he is completely docile, well trained, under the circumstances and appears to be very well liked by the staff. And he appears to like the staffs of trainers as well. He is very responsive to them even when he is not hungry. He is approximately 20 feet in length and weighs only about 5000 pounds, considerably small of stature for an orca of his age and sexual maturity. He is unusually alert and is accompanied in his small shallow pool by a male bottlenosed dolphin which has not yet shown signs of skin diseases despite his continued daily environmental and physical contact with Keiko. Keiko eats only a small amount -120 pounds of food each day- due to the excessively high water temperatures in his pool (average 75-80 plus degrees fahrenheit). These excess temperatures-killer whales are usually found in water temperatures below 60 degrees F-are also responsible for his thin stature as there is no need for extra blubber to maintain warmth in this heat, instead his problem is how to stay cool as is evidenced by the daily lethargy which overtakes the animal as each day progresses in warmer weather. His teeth are worn down from rubbing on hard surfaces and are about 50% to the gum line at the anterior third of his jaws both top and bottom.

"The most significant findings of the physical examination other than his small size and teeth are the proliferative skin lesions at his axillary region and tail stock and the overall poor condition of his skin generally which is solely the result of the improper mix of salt in his pool. The lesions are very rough and bumpy in texture and are spreading again, at this time despite the extensive previous treatments with autogenous vaccines made from tissues removed from the whale. He has also been treated with large doses of immune response stimulants to no great permanent avail.

"According to the records shown to me, Dr.S Solorzano remarked at the small skin lesions at the base of both pectoral fins shortly after the whale's arrival mexico in 1985, this would indicate a chronicity of some determination. That there have been several extensive and time consuming attempts to "cure" Keiko indicate there is not likely to be an answer to his problem in his present situation and facility. Thus, if the whale is to be saved, rehabilitated and released, his facility must be rebuilt to modern, state of the art conditions which is not likely due to the owners' lack of funding, or, he must be moved somewhere with high quality cool sea water. This means some effort on the part of those interested parties. In the past several people have seen or reported lesions similar to this in orcas in captive environments. All of these have been in man made sea water save one. All facilities involved were of questionable water quality at the time the lesions were seen. All except this one have at this writing been cleared up, apparently spontaneously, after the water quality problems involved were addressed. (I would not be surprised to have, some day, a report of these lesions naturally occurring in young wild killer whales as we have already seen with walrus and sealions).

"Thus, to save Keiko one must first rebuild his existing pools or locate a facility willing to take the whale which has cool natural sea water as its source. The animal, once in such a facility, will likely improve its skin condition spontaneously, in time, with the retrieval in its body of the natural trace elements he now lacks and he will also gain weight accordingly, when no longer stressed and challenged by the chronic heat loss problems he now faces.

"There is no doubt that whales and dolphins can successfully be released to the wild. Many people have been involved in such releases in the past, some on purpose and some accidentally.

Lanny H. Cornell, DVM

Addendum to Keiko summary:

"The histopathology report done by routine histology is non commital about infection either by bacteria or viruses. The pathologist reports he believes the skin reaction to be the result of continued insult by chemical exposure, and states he has seen this previously in whales but does not give particulars

"The electronmicroscopy report has been slow coming in as they usually are. The pathologist here reports he sees no viruses but does see numerous bacterial colonies in the tissues submitted. The tissues were taken by scalpel from the most active parts of the lesion nearest the junction with normal skin tissue visually. This is normally where one would see the invasive organism(s) and would be the best place to judge the kind of confection present. Thus, one would have to believe we are dealing with a contact dermatitis here, caused by some external source and secondarily invaded by bacteria. If this were primarily a virus or a bacterial infection one would find the causative organisms all over the wounds instead of just in some areas as we see here (emphasis added).

"Conclusions: It would appear we are dealing with an iatrogenic disease. Probably this problem is the result of chronic water quality and/or environmental problems in the animal's water and could be corrected on site through the expenditure of a proper water filtration and treatment plant, or more likely, since they have had the animal there for some years and done nothing to change their water system, by moving the animal to a proper location with viable water quality for killer whales.


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Hanna, Pepper, Beri Brown, Kelley Winship, Dianne Cameron, Heather M. Hill, and Stan Kuczaj II. (2017). A Killer Whale’s (Orcinus orca) Response to Visual Media. International Journal of Comparative Psychology, Issue 30.
Environmental enrichment is critical for maintaining cognitive welfare for animals in human care, but is subject to individual preferences. The interest in a video-based enrichment was assessed for a single killer whale (Orcinus orca) in human care. The adult female was presented 20 video recordings featuring cetaceans, elephants, or humans with each video presented in two conditions: (1) with sound and (2) without sound. Four additional presentations in which the television displayed a blank screen served as controls. All sessions were videotaped and coded for time spent viewing the recordings, behavioral responses, and visual laterality. The killer whale spent significantly more time at the television when programs were on screen compared to when the television was present but blank. She was more likely to watch videos accompanied by sound than those presented without sound. Videos were more likely to be viewed monocularly rather than binocularly, with a right eye preference when viewing the videos the first time they were presented. The highest rates of behavioral responses occurred during videos of cetaceans. These results demonstrate that one killer whale responded to video recordings of different stimuli, suggesting that video recordings may be used as a form of enrichment for cetaceans and that not all video content and formats are equally interesting.
Full paper here (620kb .pdf file).


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Herman, Louis M. (2005). Intelligence and rational behavior in the Bottlenosed Dolphin. In Rational Animals, Susan Hurley and Matthew Nudds, editors.
A rational animal is defined as one that can perceive and represent how its world is structured and functions, and can make logical inferences and draw conclusions that enable it to function effectively and productively in that world. Further, a rational animal is able to incorporate new evidence into new perspectives of the world and can then modify its behaviours appropriately—in effect creating a new or revised model of the world in which it is immersed. Rational behaviour is necessarily built on the bedrock of general and specific intellectual capacity. Intelligence, a multidimensional trait, may appear to various degrees in various behavioural, cognitive, or social domains. Data and observations are presented on dolphin cognitive performance and on apparent rational responses within four intellectual domains within the context of a variety of empirical studies that we have conducted. These domains are: (a) the declarative (semantic or representational) domain (does the dolphin display knowledge or understanding about things?); (b) the procedural domain (does the dolphin exhibit competency in means, operations, or methods?); (c) the social domain (does the dolphin reveal social awareness and appropriate responsiveness in social interactions or relations?); and (d) the domain of the self (does the dolphin exhibit knowledge or awareness of itself?). In each case, the particular experimental paradigms are briefly outlined and instances of apparent inferenctial or creative acts within each paradigm are given. Read the full chapter here (715kb .pdf file).


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Herman, L. M., Matus, D. S., Herman, E. Y. K., Ivancic, M., and Pack, A. A. (2001). The Bottlenosed Dolphin's (Tursiops truncatus) Understanding of Gestures as Symbolic Representations of its Body Parts. Animal Learning & Behavior, 29, 250-264.
We assigned gestural symbols to nine different body parts of a bottlenosed dolphin (Tursiops truncatus) (rostrum, mouth, melon, pectoral fin, dorsal fin, side, belly, genitals, tail). The dolphin was first trained to touch any floating object it chose with the body part indicated by a gestural symbol. In Experiment 1, we tested the dolphin's ability to now touch specific gesturally referenced objects using specific gesturally referenced body parts. In Experiment 2, we tested its ability to either touch or toss gesturally referenced objects with gesturally referenced body parts, or to simply display those body parts, or shake them back and forth. The acts of touching, tossing, displaying, and shaking were each associated with specific gestures and appeared in random sequences within test sessions. The results demonstrated highly significant levels of performance throughout these tasks, including many successes on the first occasions of new body-part uses. These findings provided strong evidence that the gestural symbols we used for body parts were semantically processed and understood by the dolphin as representing those body parts. In addition, the dolphin's ability to use its different body parts in the same way (e.g., touching objects with each of the nine referenced body parts), and to use the same body part in different ways (e.g., displaying or shaking its dorsal fin, or touching or tossing objects with its dorsal fin), suggested a body-image representational system for conscious awareness and conscious control of body parts similar to that postulated for humans and revealed through human brain lesion studies.
Reprints are available from:

Louis M. Herman
Kewalo Basin Marine Mammal Laboratory
1129 Ala Moana Blvd.
Honolulu HI 96814


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Jaakkola, Kelly, Jason N. Bruck, Richard C. Connor, Stephen H. Montgomery and Stephanie L. King (2020). Bias and Misrepresentation of Science Undermines Productive Discourse on Animal Welfare Policy: A Case Study. Animals 2020, 10, 1118.
Simple Summary: Creating good animal welfare-related laws, regulations, and policies depends on accurate knowledge. To that end, scientific reviews that explain and contextualize the relevant research can be powerful tools for informing decision-makers, assuming these reviews represent the state of the scientific knowledge accurately and objectively. In this commentary, we examine the major flaws, biases, and misrepresentations of the scientific literature in one such recent review regarding the welfare and care of captive killer whales. Such pervasive problems, in this or any review, make it impossible to determine the true state of knowledge of the relevant issues, and can ultimately result in misinformed, arbitrary, or even harmful decisions about animals and their care.
Abstract: Reliable scientific knowledge is crucial for informing legislative, regulatory, and policy decisions in a variety of areas. To that end, scientific reviews of topical issues can be invaluable tools for informing productive discourse and decision-making, assuming these reviews represent the target body of scientific knowledge as completely, accurately, and objectively as possible. Unfortunately, not all reviews live up to this standard. As a case in point, Marino et al.’s review regarding the welfare of killer whales in captivity contains methodological flaws and misrepresentations of the scientific literature, including problematic referencing, overinterpretation of the data, misleading word choice, and biased argumentation. These errors and misrepresentations undermine the authors’ conclusions and make it impossible to determine the true state of knowledge of the relevant issues. To achieve the goal of properly informing public discourse and policy on this and other issues, it is imperative that scientists and science communicators strive for higher standards of analysis, argumentation, and objectivity, in order to clearly communicate what is known, what is not known, what conclusions are supported by the data, and where we are lacking the data necessary to draw reliable conclusions. The full paper can be found HERE.


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John Jett, Jeffrey M. Ventre (2015). Captive killer whale (Orcinus orca) survival. Journal of Marine Mammal Science.
Killer whales (Orcinus orca) were first placed into captivity in 1961 and are now found in theme parks around the world. Despite successful breeding of captive killer whales since 1985 there is growing concern for their welfare in captivity, which often includes claims of poor survival. We employed Kaplan-Meier and Cox Proportional hazards models and annual survival rate analyses on 201 captive killer whales to discern how sex, facility (U.S. vs. foreign), captive-born vs. wild-captured, pre- vs. post-1 January 1985, and animal age upon entering captivity affect survival. Overall median survival estimate was 6.1 yr, with no difference between male and female survival. Killer whales in U.S. facilities (12.0 yr) demonstrated a significantly higher median survival than those in foreign facilities (4.4 yr), as did whales entering captivity post-1 January 1985 (11.8 yr) vs. those entering prior to 1 January 1985 (3.9 yr). Median survival for captive-born (14.1 yr) was significantly higher than wild-captured killer whales (5.5 yr), though the two failed to differ among the post-1 January 1985 cohort. Facility location and pre- vs. post-1 January 1985 were predictors of the hazard rate. Survival of captive killer whale cohorts has generally improved through time, although survival to age milestones are poor when compared to wild killer whales.


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John Jett, Jeffrey M. Ventre, Courtney S. Vail (2012). Evidence of Lethal Mosquito Transmitted Viral Disease in Captive Orcinus orca. Florida Marine Mammal Health Conference.
Two recently discovered studies document the presence of viral diseases carried by a mosquito vector in captive killer whales, Orcinus orca. In both cases, the transmission of these diseases was implicated in the cause of death for these animals. In the first case, a 25-year-old male orca, Kanduke, died suddenly and unexpectedly in the summer of 1990 at Sea World of Florida in Orlando. The necropsy in this instance identified the St. Louis encephalitis virus as the cause of death. Buck et al (1993) subsequently wrote a peer-reviewed paper describing the presence of this avian virus in the tissue of Kanduke. In the second case , a 14-year-old male orca, Taku, also died suddenly and without notable premonitory signs of illness in 2007 at Sea World of Texas in San Antonio. The necropsy in this case confirmed the presence of West Nile Virus in brain tissue and suggested the observed pathologies were consistent with those caused by West Nile Virus in other animals.

This initial evidence suggests a direct causal link between orcas maintained in public display facilities and premature death due to viruses transmitted through a mosquito vector. Further analysis is required to determine the presence of, and exposure to, these viruses in captive cetacean populations and stemming from the shallow and static environments where loafing and other surface behaviors increase susceptibility to transmission through mosquito bite. The West Nile Virus has been isolated in some populations of wild dolphins who may be similarly susceptible as a result of sustained surface behaviors in shallower coastal waters. Additionally, anecdotal eyewitness reports of mosquitoes being observed on the dorsal surfaces of killer whales in a captive environment reveals the additional risks associated with confinement and housing of this species in subtropical environments.

The occurrence of avian-borne viruses in captive killer whales requires further inquiry, and suggests the possibility of such viruses in other cetaceans maintained in captivity. This information is critical to the debate about keeping cetaceans in captivity and may provide additional explanation for past or future illnesses and death in these facilities. Free-ranging, wild killer whales are not stationary and suspended with their dorsal surfaces exposed for extended periods of time, thereby providing an opportunity for transmission via mosquitoes carrying avian viruses. No data has been found that documents these diseases in their wild counterparts.


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Lori Marino, Naomi A. Rose, Ingrid N. Visser Heather Rally, Hope Ferdowsian, Veronica Slootsky (2019). The Harmful Effects of Captivity and Chronic Stress on the Well-being of Orcas (Orcinus orca). Journal of Veterinary Behavior
Orcas are large, deep-diving cetaceans who are known for their global distribution, wide-ranging behavior, intelligence, and social complexity. They possess one of the largest and most complex brains in the mammalian kingdom. However, they are the third most common species of cetaceans kept in aquariums and marine theme parks. Most spend many years, and sometimes decades, in captivity. At the time of writing, 63 individuals are held in concrete tanks globally.

The scientific data on how both wild-caught and captive-born orcas fare in captivity is increasingly robust in demonstrating that they cannot thrive under artificial circumstances in concrete tanks. In captivity, orcas exhibit a wide range of abnormal behaviors and often die at an early age from infections and other health conditions that are uncommon in a wild setting. Though numerous papers and reports describe these adverse effects, they do not offer a clear and systematic explanation for why captive orcas suffer chronic stress and how it affects their well-being.

We describe likely mechanisms for the high levels of morbidity and mortality in captive orcas, including the impact of chronic stress on physiology and illness. We conclude that orcas are poor candidates for maintenance in captivity and suggest that a radical shift is required in their treatment, in order to meet their complex needs.
See full paper HERE.

Accepted/uncorrected ms. online The Harmful Effects of Captivity and Chronic Stress on the Well-being of Orcas (Orcinus orca)

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Marino, Lori, Scott O. Lilienfeld, Randy Malamud, Nathan Nobis and Ron Brogliod (2010). Do Zoos and Aquariums Promote Attitude Change in Visitors? A Critical Evaluation of the American Zoo and Aquarium Study. Society and Animals 18 (2010) 126-138.
Modern-day zoos and aquariums market themselves as places of education and conservation. A recent study conducted by the American Zoo and Aquarium Association (AZA) (Falk et al., 2007) is being widely heralded as the fi rst direct evidence that visits to zoos and aquariums produce long-term positive eff ects on people’s attitudes toward other animals. In this paper, we address whether this conclusion is warranted by analyzing the study’s methodological soundness. We conclude that Falk et al. (2007) contains at least six major threats to methodological validity that undermine the authors’ conclusions. Th ere remains no compelling evidence for the claim that zoos and aquariums promote attitude change, education, or interest in conservation in visitors, although further investigation of this possibility using methodologically sophisticated designs is warranted. See full paper HERE.


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Marino, Lori, Gay Bradshaw and Randy Malamud (2009). The Captivity Industry - The reality of zoos and aquariums. BEST FRIENDS MAGAZINE March/April 2009.
Millions of people visit zoos, marine parks and aquariums every year. Ostensibly, these places provide an opportunity to look at, connect with and appreciate the beauty and behavior of the animals. Indeed, everyone is drawn to the majesty and mystery of animals who look and live so differently than we do, but nonetheless seem so similar to us. But more is going on than meets the eye. Exactly what are we learning about other animals in these places? How is the zoo experience different for the animals than it is for the visitors? And what might we learn about ourselves by casting a more examining eye on the institution of zoos and aquariums?
Most zoo visitors don’t think about what it means that the animals on display have been removed from their native habitats. When they do think about it, people often come to the conclusion that captivity is a necessary evil: Zoos and aquariums are necessary because it is important for people to be able to look at other animals and because this human experience actually helps other animals in the wild. Subsequently, the price we pay for this (or, more accurately, the price the animals pay) is justified.
But this rationalization sidesteps a fundamental question: Why do zoos exist in the first place? How did they begin? To understand why zoos endure so tenaciously in Western culture, we need to look at their historical origins.
Full article HERE.


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McBain, et al. (1998). Summary Report of Evaluation Panel Convened to Assess the Health of Keiko-January 28, 1998.

Panel Members:

Dr. James McBain, Sea World, Inc.
Dr. Al Smith, Oregon State University
Dr. Jeffery Stott, University of California at Davis
Dr. Joseph Geraci, National Aquarium in Baltimore
Mr. Bud Krames, Dolphin Quest
Dr. Barbara Kohn, USDA, APHIS, AC - Facilitator

Other Contributors:

Dr. Isis Johnson, USDA, APHIS, AC
Dr. Randy Ridenour, USDA, APHIS, AC

This independent evaluation was done with the full backing and support of the Free Willy Keiko Foundation. Foundation liaisons were Mr. Joseph Gaskins and Mr. Robert Ratliffe.

The Panel wishes to thank the staff at the Free Willy Keiko Foundation and the Oregon Coast Aquarium for their cooperation with this evaluation. The Panel was welcomed with open arms. We wish to thank Dr. Lanny Cornell for his cooperation.

Keiko, a male killer whale, Orcinus orca, was transported to the United States and housed at a newly built facility within the Oregon Coast Aquarium (OCA) in January 1 1996. Since that time the animal has been under the care of the OCA and the Free Willy Keiko Foundation (FWKF). Due to the history and popularity of the whale, his health and well being have been subjected to a high degree of public and media scrutiny. In August 1997, after a change in personnel handling the day-to-day care of Keiko and after conflicting reports of his health status, APHIS was asked to facilitate the formation of an independent panel of marine mammal experts who would assess the current health status of Keiko. This panel was formed in October 1997 with the cooperation of the FWKF. The panel included veterinary experts, including a virologist and immunologist, as well as two veterinary clinicians, a behaviorist, and an APHIS representative as a facilitator. The animal was evaluated by the panel members during December 1997 and January 1998.

Keiko is an approximately 18 year old killer whale whose living condition and health concerns came to light when he was chosen to star in the movie, Free Willy. At that time, Keiko resided in a facility in Mexico (Reino Aventura), in which the pool was small and water quality was poor including inappropriate temperature. Keiko has had no conspecific companionship since he resided in Canada, but he did have dolphin companionship at Reino Aventura. After several years of negotiations and attempts to move Keiko to a more appropriate facility, arrangements were made to move him to the OCA facility, which was leased by the FWKF. Keiko's health has been a constant concern with the most visible problem being a viral (assumed) skin condition which was visible even during the filming of the movie. The skin condition did appear to improve after the transfer to the Oregon facility with its improved water quality.

Keiko was examined by a marine mammal veterinarian and samples were obtained for generally accepted routine medical testing, including a complete blood count and chemistry profile. ...

Results and Evaluation:
To gain the best picture of the health status of any animal, one should monitor appropriate parameters over time, using repeated testing. This panel was formed to evaluate a "snapshot" of Keiko's medical and behavioral condition. To provide the best evaluation under these circumstances, the panel relied on the medical and behavioral records of the animal, as well as examinations and testing done in November 1997 through January 1998.

Based on clinical pathology results, there is a high probability that Keiko developed a hepatopathy beginning in June 1997. The primary manifestation of this event was a significantly elevated liver enzyme which did not return to normal until December 1997. Keiko was treated with an antifungal drug for a suspected lung infection during the latter period of enzyme elevation. This complicated interpretation of the enzyme values since the antifungal agent used is known to occasionally produce a transient elevation in liver enzymes, which may persist over a long period of time. The return of the liver enzymes to normal levels indicated that, in the very least, the condition is in remission.

During his residency in Oregon, Keiko experienced a tooth fracture which later required extraction. There have also been multiple episodes of hematuria. Recent urinalyses demonstrate that hematuria is no longer present. Dr. Lanny Cornell, attending veterinarian for the FWKF, indicated that Keiko has a penile lesion which was the likely source of blood in the urine. The lesion has healed. Observers have reported the occurrence of behaviors described as "cramping" and "twitching." The Panel's veterinary clinicians have not seen these behaviors, nor is any video available. As a result their cause and significance cannot be determined. The behaviors have been noted since Keiko's arrival in Oregon, and to date no disease condition has been associated with them.

In late December 1997, a small skin lesion on the leading edge of the right pectoral flipper was observed. It was approximately 1" in diameter and visually appeared to be a papilloma. The lesion was biopsied, and although cytopathology was evident on the first but not the second and third growth passages, histology and initial cell culture tend to support the growth being the result of a papilloma (wart) virus. This condition is known to occur in wild and captive whales and is not considered a health challenge to Keiko (emphasis added). Other skin lesions which have been observed on Keiko have been examined and biopsied when appropriate (fresh lesions). Although such lesions resembled possible viral skin lesions, no specific viral etiology has been identified (emphasis added).

Blood (serum and buffy coats) samples were subjected to rigorous viral isolation and/or viral antigen testing for 49 antigens, including 33 serotypes of caliciviruses (oceanic and nonoceanic), marine species virus isolates of herpes virus, rotavirus-like virus, entorvirus-like virus, retrovirus-like virus, and three adenoviruses, as well as other miscellaneous viruses, including morbillivrius, parvovirus, and human hepatitis virus, canine adanovirus, and LDH virus. Antibody testing for 48 of the 49 viruses is complete at this time. Antibody tests were negative, and there were no viruses isolated (emphasis added).

Samples collected to evaluate the immunological status of Keiko revealed that he has a low circulating B-lymphocyte count and a slightly elevated total immunogloubulin level. Immunealactrophoresis of the serum proteins indicated that there may be a missing isotype of IgG. However, the significance of this finding is unknown. T-lymphocyte function appears to be adequate in this animal.

Behavioral observations of Keiko indicate a variation in his behavior patterns. In December 1997, he appeared "frustrated" and not content. In January 1998, Keiko appeared calm, if bored. Both observers felt Keiko might be feeling the effects of not having any control over his environment. However, no stereotypic or destructive (typical neurotic behaviors such as head butting or staring into the walls) swimming or other behaviors were observed.

Keiko related well to his trainers, but it was felt that the response thresholds for the training sessions were low, and Keiko's response to stimuli, though not normal, was slow. The primary reinforcement tool preferred by Keiko was tactile stimulation after a session. He does not appear to be food driven in his interactions. Keiko was provided enrichment devices and interacted with them randomly, especially enjoying the high-powered water jets used for environmental enrichment.

Overall, Keiko appeared to have no behavioral problems that adversely affected his health. Several panel members expressed concern that Keiko, may not have a great deal of stamina and that even small body movements created visible movement of skin. This apparent flaccidity of Keiko's body could indicate insufficient muscle mass, lack of muscle tone, or recent changes in weight. Keiko continues to gain weight and grown since his move to Oregon.

APHIS inspections, conducted by a 2-person team, showed the facility in compliance with the AWA regulations and standards in July 1997 and December 1997.

Summary and Recommendations
There is no current indication that Keiko is ill. He showed no clinical pathological evidence of chronic deep-seated infection during his residence in Oregon. Immunological test results are apparently within known normal parameters, and there was no evidence of recent viral challenges to 48 different viruses. Keiko appeared to be exhibiting no abnormal behavior patterns. At the time of the study, Keiko was recovering from an illness (probable hepatopathy) of several months' duration. The only known chronic condition in evidence is probable papillomatosis. This snapshot analysis must be viewed as that-a look at one point in time. Questions and concerns about Keiko's long-term health status and options for his future need to be studied over a much longer period of time. Given Keiko's past health history and ongoing concerns and scrutiny of his health, the panel makes the following recommendations:

1. Continue monitoring and follow-up testing to further establish a baseline for Keiko's medical results and to provide reliable scientific documentation of his overall health picture.

2. Given Keiko's past health history and potential future plans, a written line of authority must be established, which assures that the husbandry and medical programs are integrated in a way which places a single person in ultimate authority. This will required commitment, cooperation, and communication between the husbandry staff, water quality engineers and operators, and veterinary care personnel.

3. Ancillary to "2" above, complete and useful medical, training, and feeding records are necessary for any future evaluation of Keiko's health. These records should be well organized and readable and provide an accurate picture of all tests, treatments and responses.

4. Keiko appears to have flaccidity in his body, evidenced by highly movable skin. This could bean insufficient muscle mass or lack of muscle tone. Keiko should continue a program to improve his body tone and endurance. Such a program should include, at least, a program of regular, increasing exercise, and monitoring of weight and appetite.

5. Although Keiko's dependence on human interaction may facilitate handling by the trainers, killer whales are social creatures and should be afforded interactions with same or other compatible marine species. Section 3.109 of the AWA regulations and standards requires such access. A companion animal is recommended and should be a compatible cetacean or, if necessary, pinniped species.

6. Any decision on the rehabilitation of Keiko should be made in concert with an ongoing, long-term health study and evaluation. An expert panel assembled by the responsible parties is recommended to oversee this task.

Note: This is reprinted in full because it clears up the confusion created by the claims that Keiko ever had a contagious foreign pathogen, as suggested by Bossart, et al., and because this panel provides a model process for examining any potential candidate for release or retirement in natural habitats.


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Moore, Michael Greg Early, Kathleen Touhey, Susan Barco, Frances Gulland, Randall Wells. (2007) Rehabilitation and release of marine mammals in the United States. Marine Mammal Science 23 (4), 731–750.
Rehabilitation of stranded marine mammals elicits polarized attitudes: initially done alongside display collections, but release of rehabilitated animals has become more common. Justifications include animal welfare, management of beach use conflict, research, conservation, and public education. Rehabilitation cost and risks have been identified that vary in degree supported by data rather than perception. These include conflict with fisheries for resources, ignorance of recipient population ecology, poor understanding of long-term survival, support of the genetically not-so-fit, introduction of novel or antibiotic-resistant pathogens, harm to human health, and cost. Thus facilities must balance their welfare appeal against public education, habitat restoration, human impact reduction, and other conservation activities. Benefits to rehabilitating marine mammals are the opportunity to support the welfare of disabled animals and to publish good science and so advance our understanding of wild populations. In specific cases, the status of a population may make conservation the main reason for rehabilitation. These three reasons for rehabilitation lead to contrasting, and sometimes conflicting, management needs. We therefore outline a decision tree for rehabilitation managers using criteria for each management decision, based on welfare, logistics, conservation, research, and funding to define limits on the number of animals released to the wild.


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Newman, K., H. Markowitz (San Francisco State University, San Francisco CA 94132) (1993). Echolocation by killer whales (Orcinus orca) while in pursuit of live fish. Abstract from Marine Mammal Conference.
Echolocation use by cetaceans has been postulated to be functional in a natural environment, but might not be used as frequently in a captive setting where the water is clear and the whales are handfed. The object of this study was to see if captive Orcinus orca used echolocation when presented with live fish. We fed live coho salmon (Onchorhynchus klautch) to two captive killer whales at Marine World Africa, U.S.A., Vallejo, CA. The experiment was videotaped and recorded on a high frequency Racal 4D store four-track tape machine at 30 inches per second. A hydrophone array, consisting of a B&K 8104, a B&K 8105 and a Magnavox, was used to receive the sounds. Recordings of echolocation clicks were slowed down and analyzed with a Kay Elemetrics DSP 5500 Sonagraph and a MacAdios sound analysis program.

Results of this study demonstrate that captive killer whales will pursue, capture, and eat live fish. The whales in this study used echolocation while in pursuit of fish, as well as at other times. Preliminary analyses of echolocation clicks reveal spectral energy up to 80 kilohertz.


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Pack, A. A. & Herman, L. M. (2007) The dolphin's (Tursiops truncatus) understanding of human gazing and pointing: Knowing what and where. Journal of Comparative Psychology, 121, 34-45.
The authors tested whether the understanding by dolphins (Tursiops truncatus) of human pointing and head-gazing cues extends to knowing the identity of an indicated object as well as its location. In Experiment 1, the dolphins Phoenix and Akeakamai processed the identity of a cued object (of 2 that were present), as shown by their success in selecting a matching object from among 2 alternatives remotely located. Phoenix was errorless on first trials in this task. In Experiment 2, Phoenix reliably responded to a cued object in alternate ways, either by matching it or by acting directly on it, with each type of response signaled by a distinct gestural command given after the indicative cue. She never confused matching and acting. In Experiment 3, Akeakamai was able to process the geometry of pointing cues (but not head-gazing cues), as revealed by her errorless responses to either a proximal or distal object simultaneously present, when each object was indicated only by the angle at which the informant pointed. The overall results establish that these dolphins could identify, through indicative cues alone, what a human is attending to as well as where.


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Reiss, D., and L. Marino (2001) Mirror self-recognition in the bottlenose dolphin: a case of cognitive convergence. Proc. Natl. Acad. Sci. USA 98:5937-5942.
The ability to recognize oneself in a mirror is an exceedingly rare capacity in the animal kingdom. To date, only humans and great apes have shown convincing evidence of mirror self-recognition. Two dolphins were exposed to reflective surfaces, and both demonstrated responses consistent with the use of the mirror to investigate marked parts of the body. This ability to use a mirror to inspect parts of the body is a striking example of evolutionary convergence with great apes and humans.


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Simon, Malene, M. B. Hanson, L. Murrey, J. Tougaard and F. Ugarte. (2007). From captivity to the wild and back: An attempt to release Keiko the killer whale. Marine Mammal Science, July 2009.


A number of cetaceans have been released into the wild, with research or the improved welfare of the individuals in question as the main goal. In a few cases, releases have been monitored with methods such as telemetry or photo-identification (Gales andWaples 1993, Veit et al. 1997,Wells et al. 1998, Reynolds et al. 2000). As a rule, the animals released successfully into the wild had been captive for relatively short periods of time (e.g., 2 yr, Wells et al. 1998), were held in sea pens rather than concrete tanks, and some were released in the company of conspecifics (Veit et al. 1997, Wells et al. 1998). We describe here the last phases of a project aimed at releasing a single killer whale that had been captured as a calf, raised in tanks and kept isolated from conspecifics during most of his life. FULL PAPER HERE


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Small, R. and D. DeMaster (1995a). Survival of five species of captive marine mammals. Marine Mammal Science, Vol. 11:2, p. 209-226.
Survival in captivity was calculated for 1707 bottlenose dolphins (BD), 72 killer whales (KW), 73 white whales (WW), 3,090 California sea lions (CSL), and 47 Steller sea lions(SSL) based on data in the Marine Mammal Inventory Report (MMIR) of the NMFS. Mean annual survival rates (ASRs) between 1988 and 1992 were 0.951, 0.937, and 0.954 for BD, KW, and WW, respectively, and 0.952 and 0.969 for CSL and SSL, respectively. These estimates represent significant increases in survival for both BD and CSL over the last 5 yr. Using all of the MMIR data (1940-1992), the ASR of BD calves (less than 1yr of age) was significantly less than the ASR of non-calves (0.666 vs 0.946, P, less than 0.0001). Survival of captive-born CSL was significantly higher than those born in the wild (0.962 vs 0.945, P = 0.003), but the difference was not significantly different for BD (0.948 vs 0.944, P = 0.60). For non-calf BD and KW, captive animals survived at a slightly lower rate (BD 0.944 vs 0.961, P = 0.07; KW 0.938 vs 0.976 P less than 0.001) than animals in the wild (BD: Wells and Scott 1990, KW: Olesiuk et. al. 1990). Survival of captive non-pup SSL was slightly higher (0.968 vs 0.930) than animals in the wild (York 1994, life table analyses). Survival rates were significantly different among institutions for BD calves and non-calves, CSL pups and non-pups, and SSL non-pups.

Quote: Survival of the wild population Olesiuk et al. studied, based on approximately 250 non-calves, was significantly higher than our estimates for non-calf captive killer whales (0.976 vs. 0.938, P<0.001).


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Small, R. and D. DeMaster (1995b). Acclimation to captivity: a quantitive estimate based on survival of bottlenose dolphins and California sea lions. Marine Mammal Science, Vol. 11:4, p. 510-519.

Quote: "...over the 5-yr period between 1988 and 1992 compared with estimates based on data through 1987...Survival in captivity for killer whales Orcinus orca ...remained the same."

Note: This study plus more recent data indicates that survival in captivity for killer whales has not improved in recent years.


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Spiegl, Matthew Volk, Arie Trouwborst, Ingrid Natasha Visser (2019). Mission creep in the application of wildlife law: The progressive dilution of legal requirements regarding a wild-born orca kept for ‘research’ purposes.
Environmental law contributes to biodiversity conservation insofar as it is properly drafted and implemented. This article explores one way in which its effectiveness can be impaired: progressive dilution. This occurs when consecutive steps are taken in the law's application which in isolation may not appear much out of line and are presented as legal, but eventually render a result contrary to the law's intentions – like a military mission creeping beyond its mandate. This phenomenon is explored using the case of an orca found emaciated in the Netherlands’ waters in 2010. Captured for rehabilitation purposes and subsequently retained for strictly circumscribed scientific research, the animal somehow ended up in a commercial Spanish entertainment park, used for public performances and breeding purposes – all with express approval of various governmental authorities, including courts. The entire chain of events is analysed in light of requirements imposed by diverse (inter)national legal instruments, including the Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas (ASCOBANS), the Convention on International Trade in Endangered Species (CITES) and European Union regulations.


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Valentry, Duane (1969). Big Star All at Sea. Sea Frontiers, Vol 15:4, pp. 219-223.

Note: After almost eight years of captivity at Marineland of the Pacific, a twenty year old pilot whale named Bimbo was successfully reintroduced to the wild. Captured in January/February, 1960 at a length of 17' 6", he performed well for about three years. When his female pilot whale and dolphin companions died, Bimbo's behavior changed drastically. "One day he would be as friendly as ever, the next in a wildly agitated state or apathetic and apparently depressed." It was decided to keep him as an attraction whether or not he performed. After four years of treatment including antidepressant drugs and tranquilizers, Bimbo smashed into a window, flooding spectators. He was released in August, 1967 at a length of 20' 6", "...after much planning and weeks of isolation in a tank for physical tests to make sure he was fit for fending on his own at sea." He was resighted in 1969 near Santa Barbara, CA by a U.S. Navy collector, and again in 1974 near San Clemente identified from photographs by L Cornell and J. Prescott (pers. comm., John Prescott.)


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Wells, R. S., K. Bassos-Hull, K. S. Norris (1999). Experimental return to the wild of two bottlenose dolphins. Marine Mammal Science: Vol. 14:1, p. 51-71.
In the first scientific experiment of its kind, two young male bottlenose dolphins (Tursiops truncatus) were captured in Tampa Bay, Florida, and then returned to the wild at the same locale in October 1990, after two years in captivity. The dolphins' age/sex class and the capture and release site were selected prior to their collection. The ranging and social association patterns of the host community were examined prior to, and, including the two animals, after release. The dolphins remained together for the first month, then began interacting more with other dolphins and less with each other. Within the first year, one dolphin returned to the waters near his capture site and has remained there at least through September 1993. The other dolphin has remained in his original home range at least through June 1996. Observations of each dolphin have shown them to be fully integrated into the local dolphin societies. They displayed typical behavioral, ranging, and social association patterns. Their body condition has been excellent at each observation. They have not been observed interacting with humans. The apparent success of this experiment cannot necessarily be generalized to all potential candidates for return to the wild, but the results can be used to guide future experiments.

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