Michael T. Walsh, DVM
Over the last few years the controversies surrounding the maintenance of cetaceans have touched many aspects of zoos and aquaria which exhibit these species. A great deal of the fuel for these controversial statements results from gross information inaccuracies which have been further distorted by the popular press and by individuals who are either misguided or intentionally disruptive.
The cause of these difficulties has been insidious in its development and much of the information utilized has been quoted as "scientific fact" when in truth it is often outdated, misapplied, and non-scientific. As biologist, veterinarians and scientists, we find that our roles involve more than simply compiling scientific information. In addition we must also become educators for those in our field and the general public, dispelling inaccurate theories and clarifying misrepresented facts. We must not only attack the individual falsehoods that are portrayed, but also remind our colleagues and the public of what science is, how it functions and how a theory becomes a scientific fact.
To accomplish these goals many of us must go back to our beginnings as scientists and review the basics. Science fact usually starts as theory or as an unplanned discovery. A "theory" is defined as a supposition or assumption based on certain evidence or observation but lacking scientific proof. When a theory becomes generally accepted and firmly established, it then becomes a doctrine or principal (Tobers Medical Dictionary).
Our first goal then is to show that statements regarding basic biology, physiology and medicine of these species must be categorized as theory, fact or anecdotal. We must point out that to see a statement in print does not make it factual. Even scientific articles which are published are there for review by others in the field not to be received as the final word until they have been scrutinized, questioned, and verified or dismissed. When a statement is made we must evaluate the statement, its background, ask for proof and the source of information. We must continue to questions statements which are not only nonscientific but are often totally illogical and not supported by everyday observation.
Since the field of marine mammal care is relatively new, the number of scientist involved low, and the animals in question glorified by the media, we should begin by first evaluating our present knowledge base in light of the controversies that have been raised.
Perhaps the best known yet most misunderstood area of controversy: it is typical of the cart before the horse principle. Early observers who did not understand dolphins and their environment were easily mesmerized by this species. Before any real scientific work was done related to so called "intelligence" rating these species were being touted as super intelligent, perhaps surpassing humans. First and most importantly the measurement of intelligence in humans is difficult and controversial. In the past, human medical science attempted to associate anatomic characteristics such as brain size or mass with "intelligence". According to some neuro anatomist, this concept was dismissed years ago in the human field. The brain characteristics that may be associated with intelligence are more subtle than relative size and are concerned more with the dominance of certain brain portions (frontal lobe which is large in humans and comparatively small in cetaceans) and the amount of association tracts (white matter) that are present which is the "wiring" for the different portions of the brain allowing communication between its parts (which are reduced in cetaceans). In short it is not how much total is there but rather what is there and how is it connected.
As with all scientific principles, the claim on paper for high intelligence must be corroborated with daily observation and verification. This does not appear to be the case. What we do know about cetaceans is that they are highly adaptable and that within their own species some are more intelligent than others. At present there is no scientific information to state that these are "highly intelligent" species in a human comparative sense.
Cetaceans are Voluntary Breathers
It has been said that cetaceans and other marine mammals are voluntary breathers having to think about each breath taken. This apparently is to be an attempt to tie in superior intellect with the ability to think about each breath.
There is no physical or scientific evidence to verify this supposition. It appears to be based partially on early investigations with anesthetic agents and popular myth. Current clinical investigations into the use of sedatives and anesthetics have shown that these individuals are involuntary breathers. Again, the observation of the species does not verify the voluntary breathing theory. The breath holding capability of cetaceans is difficult for some to comprehend but it is in fact very similar to our own. Though land dwellers, we are capable of breath holding and swimming under water, that is, we can voluntarily extend our breath holding capability. Cetaceans with their enhanced capability can also extend their cycle beyond the normal controls even though those controls are present.
Cetaceans in captivity exhibit abnormal lesions such as rake marks and corneal disease.
This contention illustrates more than most that its proponents know very little about what is normal in dolphins. This is a widespread misconception by many in the general public who have never been educated on the realities of life in the wild. It is thought to be an idyllic existence full of fun and play as it is often portrayed in the brief encounters with underwater wildlife photographers. Little to no information is shown about low survivorship after birth, parasites, lung disease, kidney disease, intra-species injury, starvation and the truth behind strandings. Dermal abrasions and corneal lesions are commonly found in animals in the wild. In an attempt to elicit sympathy and produce a false image of the captive environment, some individuals and groups feel justified in distorting the truth or they are naive about wild individuals. The facts are that corneas are not being burned by chlorine, rake marks are a normal part of dolphin society, not all animals have rake marks, cetaceans are not rendered deaf from sonar reflection, and the medical personnel responsible for the health care of cetaceans do not shelve their ethics and falsify records in order to justify exhibiting these animals.
Animal Longevity and Average Lifespan
The contention that in captivity cetaceans live an average of 4-5 years has never been taken realistically by anyone except its proponents. It is amazing then that it is one of the most often quoted misconceptions and is a classic example of how numbers can be twisted and abused.
From a medical and zoological perspective we realize that in the short amount of time cetaceans have been maintained, that there is a great difference in lifespan between animals maintained 25 years ago and today. In parallel with humans, and other species maintained in zoos, each year brings improvement in average lifespan and our knowledge about the species. It is medically irresponsible to compare lifespan now with that 20 years ago and average those "statistics" together.
A great deal of the justification for this being a problem is the tendency to compare lifespan to that in the wild based on limited observation (only 20 years with 90% of that above water with killer whales). Observation and investigation of dolphins on the west coast of Florida has pointed to animals in their 40's as judged by tooth layers. From a scientific standpoint it must be pointed out that it has not been shown that tooth layer aging is accurate in older animals.
It is interesting to note that once the 40+ years is mentioned then all animals will be judged by this age with anyone less having died too early. Yet we realize from human lifespan numbers that most of us will only reach 50-70% of our potential maximum lifespan. This increase is as a result of improved health care, better diet and improved basic hygiene. Without these improvements the wild human may average a lifespan between 30-45 years. Nonetheless, some humans live well beyond this, but the normal average was still only 30-40% of their potential. The average layperson has little grasp of any of this, judging the past, and the species by their own experience.
All of these and other supposed controversies can only exist if we do not question statements which have no basis in fact. This does not mean we can afford to waste time in meaningless dialogue with countless groups, but as scientist we can continue to educate and uncover the truth. As we all know, this requires time and commitment and require that we ourselves exercise caution and avoid fanning the flames with inaccurate information.