Tilikum home
In wake of the death of Tilikum, long-time Sea World resident and breakout star of 2013’s Blackfish, I am taking a few words to consider the type of life offered to captive killer whales (Orcinus orca).
The killer whale is named so, apparently from a mistranslation from the Spanish for whale killer, as a result of the observance of pods hunting baleen whales. These animals are also titled the orca, a name becoming increasingly popular among scientists in an attempt to avoid the unfavourable image conjured up by the word killer. Initially popularised by the Free Willy franchise, for those not previously familiar with them, they were most recently brought to tabloid headlines with the release of 2013’s documentary Blackfish (a must watch for those who have yet to).
Through the years since 1961 (the first recorded captive killer whale) as aquatic parks, notably Sea World, grew in size and in turn grew their captive orca populations, both visitation rates and controversy have risen. For many, and for most wildlife and environmental enthusiasts, the idea of keeping captive animals has been viewed negatively, albeit with various exceptions regarding conservation efforts and rehabilitation. With no clear intent or need to conserve orcas around the time of their initial capture and relocation to parks, the same misgivings rung true for these aquatic parks.
I have taken a few days to compile what I could find from reputable scientific journals and organisations regarding various comparisons in life history traits of free ranging killer whale populations, and killer whales in captivity, both captured and captive-bred.
It is well documented that orcas are regularly found in pods of 20-75 individuals in the wild. Pods are well structured in age and sex, containing many members of the same family who appear to exhibit bonds unseen between unrelated individuals. Mothering orcas are some of the most important members of their pod, and these individuals experience the earliest onset reproductive senescence (menopause) relative to life expectancy of any species – they live the longest after senescence has occurred. Communication between these individuals is key, which is achieved through open water acoustics. Acoustics in water are affected by a multitude of environmental factors including salinity, depth and temperature, all of which are therefore important to orca communication. Unfortunately captive orcas are kept, most often separate from other individuals, in sterile tanks up to a maximum depth of 36 feet, or volume of 6 million gallons.
While changes in the use of water bodies over the past century involving heavier boat traffic has provided multiple stressors for all aquatic animals, namely those using acoustic communication, many stress related responses exhibited by orcas have only been documented in captivity. It is not uncommon for individuals to chew on metal bars and concrete frames in their tanks, referred to as gate chewing, as a sign of frustration. This is evidence of a stress related response, which also results in further health deteriorations such as in dentition. Other common issues observed solely in captivity include the recognisable collapsing of the dorsal fin (recorded in less than 1% of wild orcas) which is caused by an increase in the amount of time gravity acts on the fin at the surface of the water.
It is believed that in the 56 years that orcas have been kept captive there have been in excess of 100 incidents of aggression towards humans in captive environments, resulting in four deaths. There has been in recorded history no human deaths as a direct result of the single incident of aggression exhibited towards a human by a wild orca.
One of the biggest controversies is over the life expectancy that orcas in captivity have, before even considering their quality of life as intelligent beings. The average life expectancy of wild orcas is: 30 for males, and 50 for females with individuals recorded between 50 and 60, and up to 100 years old for each sex respectively. A 2015 study claims as follows: An average life expectancy of 41.6 years was the result of analysis on all captive orcas regardless of sex, with an average expected maximum age of 47.7 for those born in captivity. Although these results do not take into account the decrease in annual survival rate of individuals post age 30. Data from the last decade suggests that life expectancy for captive orcas at Sea World facilities has increased incrementally over the decades since captive individuals were first obtained, to a point where it is comparable to wild life expectancy. However in science, it is always important to think critically about gathered information. And it is thus worth mentioning that the study claiming that life history traits including life expectancy, annual survival rate and fecundity aren’t significantly different between captive (bred and captured) populations and free-ranging populations was, at least in part, supported by Sea World.
Other sources suggest that there is a 13 year average life-span for orcas at Sea World parks, with some dying as young as 12 days (2 of 33 recorded captive births did not survive past 40 days) and many more dying of respiratory problems within a few years. With over 90% of captive individuals not living past age 25, one should also note that many are already a few years of age when arriving at parks, and thus in-captivity life expectancy should potentially only account for years spent in captivity before death which would further decrease.
Now back to Tilikum, a martyr for his cause certainly. An individual who died aged 36, outliving the average expectancy for male orcas even in the wild, after spending 34 of those years in captivity. 34 years, three attacks and three (human and 46 orca) deaths Sea World is responsible for.
Bibliography:
Robeck, T.R . (2015) Comparisons of life-history parameters between free-ranging and captive killer whale (Orcinus orca) populations for application toward species management, pp.1055-1070
