It has long seemed that one of the biggest challenges of keeping orcas healthy in captivity is dental care. Many captive orcas wear down and break their teeth by fighting, and chewing on concrete or the gates between pools. If the damage is bad enough SeaWorld and other facilities drill out the teeth and then flush them daily. Even so, the damaged teeth become prone to infection, infections which can lead to serious health problems.
To more fully gauge and understand the extent of this threat, John Jett and Jeff Ventre, two former SeaWorld trainers, along with other researchers, studied dental damage in captive orcas, using photography to catalogue and evaluate the problem. The result, “Tooth Damage In Captive Orcas, which appears in the Archives Of Oral Biology, is a comprehensive, scientific, assessment that reveals how common and extensive tooth damage in captivity really is.
Highlights of the paper include:
Mouth images of 29 orca held in captivity were evaluated for tooth damage. Individual teeth in the mandible and maxilla were scored for coronal wear, wear at or below the gum line, fractures, bore holes and missing.
Dental damage was present in all whales examined, and the various pathologies were observed across animals with different durations of captivity, across both sexes, in captive-born and wild-captured whales as well as whales kept in each facility. Dental pathology was especially prominent for mandibular teeth.
Forty five percent of whales exhibited “moderate” mean mandibular coronal wear, and an additional 24% exhibited “major” to “extreme” wear.
Bore holes were observed primarily within anterior mandibular teeth, with more than 61% of tooth 2 and 3 and 47.27% of tooth 4 bearing evidence of having undergone the modified pulpotomy procedure.
Dental damage begins early in a captive whale’s life.
Both conspecific aggression among captive whales and oral stereotypies such as biting and chewing on concrete and steel tank surfaces likely contributed to the tooth pathology observed.
Keeping any animal captive–especially a highly evolved, free-ranging, top predator–presents unusual health issues, both mental and physical. It is unlikely many marine park visitors suspect that tooth damage is one of the leading health challenges for captive orcas. But this paper makes clear how common the problem is, and how severe the damage can be. That is important, because the more we understand the negative side-effects of keeping animals captive for entertainment, the better we can weigh the ethical question of whether it is justified.
Although unreported in wild orca populations, mosquito-transmitted diseases have killed at least two captive orcas
(Orcinus orca) in U.S. theme parks. St. Louis Encephalitis Virus (SLEV) was implicated in the 1990 death of the male orca Kanduke,
held at SeaWorld of Florida. In the second case, West Nile Virus (WNV) killed male orca Taku at SeaWorld of Texas in 2007.
Captive environments increase vulnerability to mosquitotransmitted diseases in a variety of ways. Unlike their wild counterparts who are rarely stationary, captive orcas typically spend hours each day (mostly at night) floating motionless (logging) during which time biting mosquitoes access their exposed dorsal surfaces. Mosquitoes are attracted to exhaled carbon dioxide, heat and dark surfaces, all of which are present during logging behavior. Further, captive orcas are often housed in geographic locations receiving high ultraviolet radiation, which acts as an immunosuppressant. Unfortunately, many of these facilities offer the animals little shade protection. Additionally, many captive orcas have broken, ground and bored teeth through which bacteria may enter the bloodstream, thus further compromising their ability to fight various pathogens. Given the often compromised health of captive orcas, and given that mosquito-transmitted viral outbreaks are likely to occur in the future, mosquito-transmitted diseases such as SLEV and WNV remain persistent health risks for captive orcas held in the U.S.
This is an important insight into how captivity affects the lives of killer whales, and what is particularly interesting is how a confluence of captivity-related issues–logging, temperatures, lack of shade, teeth-drilling, etc–combine to create a vector of vulnerability that wild orcas likely do not experience. Which is one more reason that mortality in captivity is greater than mortality in the wild. Very well-done, informative, fact-based, work.