[This is a point-by-point response to SeaWorld's claims regarding orca lifespan.]

[SeaWorld:] The issue of killer whale lifespan is one that is often misconstrued and overly simplified. The simple truth is that no one knows.

The simple truth is that we have a very good idea what the lifespan for wild killer whales is. The only source that says “no one knows” is SeaWorld. The Encyclopedia of Marine Mammals, NOAA, and many killer whale researchers DO know because there are good data on this parameter from wild populations.

Only a small percentage of the world's wild killer whales -- a few populations off the coasts of Washington, British Columbia and Alaska -- have been studied long enough to produce statistically valid research. 

This directly contradicts the previous statement that “no one knows.” The results of the research mentioned here are not uncertain or disputed by anyone but SeaWorld. These populations give us an estimated maximum potential re: killer whale lifespan -- this is how long the species CAN live, under certain natural circumstances. If captivity is a good environment for them, then captive killer whale life span should at a minimum match, and even exceed, these values.

 Killer whales live all over the world in distinct populations -- some very different from each other -- and we do not have enough adequate science to know if different ecotypes have different lifespans.

This should not matter, based on SeaWorld’s own arguments. SeaWorld says captivity is a healthy environment, so its killer whales should be living lives at the longer end of the species’ potential (different ecotypes are not yet considered different species and even if they were, there is no reason to assume their inherent maximum longevities would be different -- any differences in life span would likely be caused by extrinsic environmental factors). Captive killer whales should overall be living 50 to 90 years for females and 30 to 70 years for males, barring stochastic events. In addition, SeaWorld mixes ecotypes and different geographic regions within its collection and in its breeding program. This is not only inappropriate from a conservation standpoint but makes this bullet point somewhat irrelevant.

Additionally, when attempting to compare the lifespan of wild populations vs. those that live in zoos, the data are limited. There is a relatively small number of killer whales in our care, and these limited numbers make direct comparisons tenuous and misleading. 

The sample size is now over 200 animals, which is comparable in size to the wild populations in the Pacific Northwest to which SeaWorld refers earlier. It is now large enough for statistically valid comparisons, when using appropriate parameters (annual survivorship rate, as opposed to longevity or mean life expectancy) and statistical tests. 

What we do know: The data we do have show that killer whales at SeaWorld are living as long as their counterparts in the wild. 

The data we do have actually show that killer whales at SeaWorld are NOT living as long as their counterparts in the wild, but regardless, SeaWorld cannot logically argue “no one knows how long they live,” and then say “but we do know they are living longer in captivity.” These statements are contradictory.

In peer-reviewed studies, scientists estimate that the average, or mean, life expectancy for a female is 30 years and a male is 19 years in the Pacific Northwest.[1].

This is a spectacular example of cherry picking data. SeaWorld has chosen the values for whales in the Pacific Northwest during a time when prey were in steep decline. SeaWorld ignored the values for whales during periods of population growth (which are more indicative of the potential for this species). As an analogy, SeaWorld has chosen data from a population that is experiencing a famine, versus a population with plenty to eat. During periods of population growth and plentiful food supply (the latter presumably being the case in captivity), mean life expectancy for females is 50 and for males is 30. 

As an example of additional cherry picking, SeaWorld ignores the data in the papers it cites on this web page that illustrate the complete lack of dispersal from matrilines, the age at which females give birth for the first time, and the sexual versus physical maturity of males. Captive killer whales at SeaWorld are frequently separated from their mothers, give birth years before the natural first age at parturition, and are used as studs years before physical maturity.

For whales in Southeastern Alaska, the maximum longevity appears to be in the 50s for females and late 30s for males.[2] 

SeaWorld has completely misread this paper and either ignored or missed key information included in its text. These were not the maximum longevity figures for this population; these were merely the maximum age classes analyzed in the paper for ASR. The authors only analyzed data for females of estimated ages up to 50-54 (and for males up to 35-41). They did not go beyond these age classes because data on age became more uncertain beyond them (they couldn’t put the animals older than 54 for females or 41 for males into five-year age categories with certainty -- animals older than this WERE present in the population). The authors clearly stated that they assumed the maximum longevity in their population was the same as in the Pacific Northwest, i.e., 80-90 years for females and 60-70 for males. 

So, in those two areas of the world, female killer whales live around 30 to 50 years and males live around 19 to 30 years. 

No, they do not. They live “around” 50-90 years for females and 30-70 years for males.

SeaWorld has several killer whales in their 30s and one that is close to 50. 

The ONE whale SeaWorld mentions in its collection (whose name is Corky) who is close to 50 is an outlier. Focusing on her as an example that SeaWorld’s female whales live “around” 30 to 50 years is like saying “Granny” -- J2, a whale in the southern resident population of Puget Sound -- is an example of wild whales living “around” 100 years. It is more accurate to say that females in this population live “around” 50-90 years and that any females older than this are outliers. ALL but one of SeaWorld’s female whales are (or were at the time of their death) younger than 40. That one whale, Corky, is an outlier. In addition, less than a half dozen out of more than 60 whales at SeaWorld since 1965 have reached the mean life expectancy for wild whales in Southeast Alaska and the Pacific Northwest. Only two males have surpassed the mean for their sex (they are over 30 years of age and one of these is probably 36 or 37) and many have died well before the wild mean, suggesting strongly that the mean life expectancy in captivity is far below that in the wild.

A look at the most recent research Because it can be misleading to compare life expectancies between whales in the wild and those in captivity, scientists believe that the most accurate comparison to use is the "Annual Survival Rate" (ASR). ASR is an estimate of the percentage of whales in a population expected to survive each year.[2],[3] 

For instance: if we were studying a specific community of humans, this method takes into account that – in that specific population -- the number of children that are expected to survive another year is high, and the number of senior citizens expected to survive is low. 

This statement is incorrect. ASR does not “take into account” the probabilities of survival for different age classes within a sample (also, survivorship curves for mammals are U-shaped in nature – the probabilities of annual survivorship for younger and older animals are both low compared to “prime of life” animals). It is a snapshot of the survivorship probability from one year to the next of any particular sample, whether it is mixed age or a specific age category or a specific sex or whatever.

According to recent studies, the current ASR of SeaWorld’s killer whales is similar to that of the Alaskan Resident whales.[2] 

No, it is not. There have been no statistical analyses, so it is invalid to claim the values are similar. However, the most recently presented ASR – not peer-reviewed, but presented at a scientific conference (Innes et al. in prep – this is for the period 2005-2013) – calculated from captive killer whale data in the Marine Mammal Inventory Report is lower, at 0.983, than the Alaskan ASR for both sexes aged 1.5-2.5 (0.997), females aged 15-19 (0.996), both sexes aged 10.5-14.5 (0.992), both sexes aged 3.5-5.5 (0.991), females aged 25-29 (0.990), both sexes aged 6.5-9.5 (0.989), females aged 20-24 (0.987), and even males aged 15-19 (0.986). It is higher than all other age classes (mixed and single sex) in Alaska. The Matkin et al. paper did not calculate an overall ASR, so none of these comparisons (a mixed age/mixed sex group vs. a specific age/sex class) is actually valid. Regardless, they are not similar. (Note: the MMIR ASR for the decade 1995-2004 was 0.968, lower than most of the Alaskan values.)

The study determined that the overall average ASR for that population is 0.976. (This means that there is a 97.6 percent chance that a whale in that population will live another year.)

Matkin et al. (2013) did not calculate an overall ASR of 0.976 (they did not calculate an overall ASR at all). Olesiuk et al. (1990) did.

SeaWorld compared the study’s results to the ASR’s of its killer whale population. To take into account advancements in medical care and knowledge, we looked at four different time spans (1968-1983, 1984- 1993, 1994-2003, and 2004-2013). Not surprisingly, the trend improves over time. The fairest comparisons are the two most recent 10-year periods from 1994 to present, during which the whales have had the opportunity to benefit from advancements in our knowledge, facilities, and husbandry and veterinary practices. 

In this paragraph, SeaWorld essentially acknowledges experimenting with the lives of the whales in its collection over the past five decades. It says “not surprisingly,” but it is in fact surprising that SeaWorld would admit so nonchalantly that its alleged expertise in maintaining these animals in captivity is based on a trial-and-error learning curve that resulted in early death for whales through the 1990s. Regardless, its claim that advancements in its knowledge, facilities, and husbandry and veterinary practices have improved to the point where captive ASRs now match those in the wild is unsubstantiated – no statistical analyses have been done on these values and as shown above, some of the wild ASRs are exceptionally high and certainly higher than those from MMIR data (which is primarily SeaWorld data). Also, why are no SeaWorld data actually provided on this page? SeaWorld says it looked at these four different time periods, but does not offer any actual values.

For both of those most recent periods of time, there is no significant difference between the ASR of our whales and the ASR of wild populations. 

This is a statistical statement. What tests did SeaWorld use and what were the actual values? This statement is meaningless without data.

Why it is important to take a careful look at numbers
Statistics used to determine longevity can use a few different methods, and can be manipulated to mislead people into false assumptions.
 

This statement is hypocritical, as this entire web page is SeaWorld manipulating information to mislead people into false assumptions. SeaWorld claims that there is no SIGNIFICANT difference between the ASR of its whales and the ASR of wild populations, but offers no values or statistical test results to back up this claim. That is manipulation. In fact, the only peer-reviewed analysis currently available (Small & DeMaster 1995) shows that the overall ASR in captivity (0.938) for non-calves (any whale older than 1 year) is significantly LOWER than the overall ASR from the wild (0.976). SeaWorld must subject its claims to peer review or at the least provide actual data so others can confirm its claims. Making claims without substantiation is manipulation. 

My colleagues and I are working on updating the ASRs in captivity, using data through 2011 and breaking down the data into age categories and decades. But these results have not yet gone through peer-review, so I won’t post them here. However, we will be submitting a manuscript to a journal for peer-review. Until SeaWorld is willing to do the same (let alone provide some values on this web page, as I have for Small & DeMaster), its commentary on this issue is nothing but manipulation and misleading people into false assumptions.

 For instance, many animal rights activists will mix different types of studies when comparing the lifespan of wild vs. captive whales -- citing side-by-side the maximum longevity for wild whales, but the average longevity of captive whales. 

Who are these “many animal rights activists”? Animal protection advocates with degrees (such as Dr. Lori Marino, Dr. Ingrid Visser, and myself) do not do this. One reason why we do not is that there are no valid average longevity values for captive killer whales. We do point out, however, that to date, the vast majority of captive whales who have died were far younger than the mean life expectancy of wild whales and that the vast majority of those captive whales who are still alive are ALSO younger than the mean life expectancy of wild whales – most living captive killer whales (both sexes) are far younger than 25 years of age. These are simple facts. In addition, SeaWorld cherry picks data from worst-case scenarios rather than normal scenarios when discussing life expectancies and longevity in the wild. So once again, this type of accusation is not only baseless but hypocritical.

Using a human analogy: if one man in Japan happened to live to 116 years, but the average life expectancy for a male in the U.S. is 76 years, it would be false to say that “Living in the U.S. causes early death. People have a lifespan of 116, but in the U.S. they die early at age 76.” 

This is true (and not what I do). It is also false to say that “During times of famine, people live normal life spans,” because they do not -- famine actually does cause early death. So one cannot use average life spans during times of famine when trying to determine what the normal average life expectancy of humans -- or whales -- is. 

Let’s look at some statistical results that can be generated and questions that can be asked which have often led to confusion or misrepresentation during population comparisons.[4] 

1. What results are we comparing? Different studies examine: 

- The oldest a whale can get, which is maximum potential life-span. Since individual killer whales in the wild have only been followed for 40 years, the oldest known-age animal cannot exceed this value. All other proposed maximum-age projections are simply estimates. 

Yes -- and these estimates are empirically based. While it is true that the oldest known-age animal in the Pacific Northwest cannot exceed 41 years of age, animals with estimated ages have MINIMUM possible ages. The females first observed as adults in 1973, based on size and the presence of at least one dependent calf, MUST be older than 41 if they are still alive (and several such females ARE still alive). In fact, if they had one dependent calf at the study’s beginning, they must be AT LEAST 56 now (41 + 15 – average age at first parturition). If they had two dependent calves (one newborn and one approximately five years old based on size), they must now be at least 61 years old (41+ 15 + 5). And so on -- if a female had four young animals accompanying her (newborn, 5, 10, and 15 years of age based on size and dorsal fin development) in 1973, then if she is still alive, her age today would be at least 71 years of age. This is how J2 (Granny) has been aged -- when the study began, the whales accompanying her, all of whom have since died or are still with her, had estimated ages (based on size and dorsal fin development) that suggested she was at least 55-65 years of age. Thus she would now be 96-106 years of age today (and most whale observers in the Pacific Northwest say she is 103 this year). Same for males -- several were physically mature adults (full-grown dorsal fin) when the study began and if they are still alive, they MUST be older than 41 (and since physical maturity occurs at approximately 20, they are likely to be at least 61 years of age). 

- The average age at death of a whale that lives past its first year of life. This statistic creates bias against animals that are currently alive by excluding them from the analysis. It is not considered an accurate representation of population longevity. 

- The life expectancy of a whale. This further must be defined as whether that includes any animal from moment of birth, or only those that survive to a particular known “starting age.” 

The straw man SeaWorld has constructed here is implying that all “animal rights” calculations -- which apparently are any calculations that do not support SeaWorld’s claims -- are guilty of all these fallacies. But not all of the “animal rights” calculations do make these errors -- nor are all of the calculations that do not support SeaWorld’s claims by “animal rights activists.” Small and DeMaster were government scientists.

2. When comparing results, what variables have been taken into account? 

Because of different variables, comparisons among different populations are often unreliable. This applies to comparing wild whales that live in different regions of the world, and also when comparing wild whales vs. those that live in zoological facilities. 

For whales in the wild, those variables include different whale population life histories and environmental stressors: variations in food availability, shifting climactic conditions, and pollution. All affect wild whale health and mortality, and especially over short periods of time, can significantly skew statistics. 

Exactly. All of these are extrinsic factors, not inherent to the species. The values from the Pacific Northwest represent the currently known best possible life expectancies for this species. Given that the only peer-reviewed ASR values in captivity are significantly worse than those in this wild population, there must be extrinsic variables in captivity that affect the survivorship of captive whales. These variables must not be the same as those listed here by SeaWorld, as SeaWorld claims these factors are not present in captivity (it claims whales in captivity are protected from these stressors, such as low food availability, shifting climactic conditions, and pollution).

Other variables that affect comparisons include: 

- Are young calves included? Studies of killer whale longevity in the wild generally exclude mortality of whales less than six months of age. They do this for a very practical reason: killer whale calves often do not become known to the scientists studying them in the wild until they are at least six months old. 

All ASR comparisons in the literature (wild vs. captivity) compare ASRs of non-calves only. This point is a red herring. 

So, to accurately compare the results of studies in the wild (which exclude these very young calves that have a high mortality rate), with the results of studies of captive whales (which typically include every birth), one should make a similar exclusion. This ensures that both sets of results are comparable. This is something animal activist groups almost never do. 

Most animal activists fail to make ASR comparisons at all, according to SeaWorld above. This page has multiple internal contradictions. Those animal groups that do use ASR, because they have scientists with the necessary expertise, always exclude calves and compare non-calves only.

Any comparison of research on young killer whale calves – even with the concern noted above – still shows that calves at SeaWorld have a much greater rate of survival than calves in the wild. 

Once again, SeaWorld displays extraordinary logical inconsistency. It just pointed out that calf survival rate is essentially unknown in the wild; therefore, it cannot make the claim that SeaWorld calves have a much greater rate of survival than those in the wild.

But for the purposes of this discussion, and our best effort to equate variables, we have left calves younger than 6 months of age as a separate group, and out of both sides of this equation. 

- Are unusual exposures included? In studies of wild whales, scientists will sometimes exclude animals exposed to a specific unusual event. For example, a study of Southern Alaskan resident killer whales excluded those that had been exposed to the Exxon Valdez oil spill.[5] 

This was a stochastic event. If SeaWorld had a filtration breakdown and several of its whales died because of some kind of catastrophic exposure to pathogens or contaminants that occurred during the incident, it would almost certainly not include these animals in subsequent ASR calculations. While Matkin et al. did exclude deaths during the Exxon Valdez spill, they included all animals who experienced a period of food shortage, when salmon runs were poor.

Although this was an appropriate way to structure that particular study, it also can be argued that these data then underestimate the risks faced in the wild and therefore unfairly skews any comparison with animals housed in zoos. 

Many kinds of data are excluded in captive studies. Whales that die in the first 3 days. Whales of unknown disposition (surprisingly large numbers). Small and DeMaster excluded a number of MMIR animals from their dataset for various reasons, including these.

- In facilities, do you include whales that arrive already in compromised health? Whales that come to a facility in a compromised state of health, such as from beaching and/or illness, should be excluded from zoological whale studies, because these whales would not be alive in the wild. 

This is yet another example of whales who are excluded from captive datasets. All of these exclusions, if they introduce bias, bias the dataset in favor of the industry. In addition, it is not known that whales who are sent to captive facilities in compromised health for rehabilitation would “not be alive in the wild.” Sometimes when stranded cetaceans are refloated, they survive. Cetaceans that have not actually come ashore but are “rescued” afloat may have survived if they had been left alone. There is simply no way to know -- SeaWorld is presuming without empirical basis.

 - In facilities, do you use data that reflect current conditions and the evolved state of medical knowledge and care? We know that care of killer whales has improved immensely -- thanks to research made possible by maintaining a population of killer whales that we work with on a daily basis. 

Again, SeaWorld essentially admits here that it has been experimenting with killer whale lives. It is a truism that this learning curve/research would not have been necessary if the industry had not chosen to bring these animals into captivity in the first place. The fact that SeaWorld had to learn so much -- and that it is apparently still learning -- about captive care after 50 years of holding this species is arguably unethical, given what we have learned about this species from wild studies. We know killer whales have strong family bonds, long lives, and cultural differences among populations -- keeping them in captivity, given these characteristics PLUS the fact that SeaWorld admits it is still on the upside of a learning curve regarding husbandry and veterinary care, is entirely inappropriate.

For this reason, the studies that best reflect the longevity of SeaWorld’s killer whales are those that have taken place since the 1980s. 

3. How many whales are we studying? As we mentioned previously, in any study, it’s important to have a statistically valid sample size, and captive populations tend to be small, allowing individual aberrations to skew the numbers and distort comparisons with studies of larger populations. There is no simple solution to this problem, so we need to consider this effect when evaluating our results. 

This is one reason my colleagues and I are still looking for the appropriate statistical test for our ASR analyses. It is indeed not straightforward to compare results from the wild and captivity and we are considering these sample size effects. SeaWorld, of course, has not described the statistical test it used (nor has it presented the results of this test) when it claims it found no significant difference between its ASR and the latest wild ASRs. It also strongly emphasizes the presence of a whale nearing 50 years of age in its collection, when in fact she is an outlier who is skewing the captive results upward.

Looking to the future
Moreover, life in the wild for killer whales is getting more difficult, as recent research shows. 

The northern residents and the southeast Alaskan whales are doing well. Other populations of killer whales also appear robust. Certainly some are doing poorly and one is clearly endangered. Regardless, things getting worse in the wild does not somehow justify captivity. That’s a logical fallacy. In addition, SeaWorld claims that it is highly effective at educating people about the conservation needs of wild whales and inspiring a conservation ethic in millions of visitors every year. Given this claim, it seems legitimate to ask why things are deteriorating in the wild so rapidly. Clearly SeaWorld cannot be held solely responsible for the failure of the general public to grasp the significance of phenomena like climate change and ocean acidification, but the proof is in the pudding. SeaWorld and facilities like it are clearly NOT doing as good a job of educating the public as they claim when there is so little evidence of such understanding in the ways the public relates to the ocean environment. SeaWorld itself keeps pointing out how degraded nature is (in a way that is inherently anti-conservation, implying that its concrete tanks are a better home for killer whales!). 

(Conservation and animal protection organizations must also take some responsibility for this failure to educate the public effectively, but most of them do not have the constituency size that SeaWorld has or make the sweeping claims of effectiveness that SeaWorld does and many are working to change their standard operating procedures to increase the effectiveness of their communication with the public. SeaWorld refuses to acknowledge the need to change.)

A study released in October 2013 by the Killer whale Relief Citizens’ Alliance found that among Southern Resident killer whales, the number of reproductive-age males has declined 26 percent since 2009 – reaching the lowest number of breeding-age males since 2003, and a total population of only 80.[6] These studies are a reminder that the hazards and hardships of life in the wild should not be ignored or idealized when making comparisons with captivity, and they underscore the critical role that SeaWorld researchers are playing in helping to understand, protect and preserve those wild populations. 

And this is where SeaWorld’s hypocrisy peaks. It was the removal of an entire generation of whales for public display by SeaWorld and others in the 1960s and 1970s that caused severe depletion and social disruption in this population. While the failure of the population to recover from this decimation is largely attributable to other factors, the fact that it had no reserves – in terms of numbers of individuals or possibly genetic diversity – to withstand the habitat degradation with which it has been faced since the 1980s can be laid solidly at the door of the industry.

Independent of the complexity of the subject is our motivation, our mission, our expectation that longevity by any measure of the whales that we are privileged to care for in our parks will continue to increase and will one day outpace that of wild populations. 

So rather than recognizing that its husbandry experiment has failed, SeaWorld will continue to kill killer whales with the same efficiency as salmon shortages and disease and whatever other causes of death face wild whales until the results “one day” outpace wild populations. This is of course yet another internal contradiction, but in favor of the whales this time – SeaWorld earlier claimed that “no one knows” how long whales live in the wild, but admits here that longevity of captive whales still does NOT outpace that of wild populations. If captivity is benign, as SeaWorld claims, captive whale longevity and ASR should have long since outpaced the wild. 

It is of note that SeaWorld never expresses any remorse for the whales it apparently accepts it killed in the early days of this learning curve, right through to the 1990s. 

In a letter SeaWorld president Jim Atchison wrote to my former employer, The Humane Society of the United States, Mr. Atchison accused The HSUS of “cost[ing] an innocent animal its life.” He was referring to the rehabilitation and reintroduction project involving Keiko, the whale who starred in the 1993 film “Free Willy.” This letter completely ignored that Keiko survived for five years in the wild – quite probably five more years than he would have survived if he had remained in the inadequate facility in which he lived in Mexico City, where SeaWorld left him after considering buying him in 1991. Keiko lived to the age of approximately 26 -- longer than most male killer whales at SeaWorld (yet whenever a young whale dies at SeaWorld, its public relations department will suggest that “death is a natural part of life”). Yet on this web page, SeaWorld admits that its efforts to maintain captive killer whales has been subject to a learning curve, during which a fair number of whales have died prematurely. I can only once again point to the hypocrisy of this line of argument. 

If, in nearly 50 years of keeping this species in captivity, SeaWorld has not yet matched (by my calculations) or surpassed (by SeaWorld’s calculations) the average life expectancy of wild whales, it is highly arguable that it is time to end this experiment in husbandry and phase out the public display of killer whales. There is no justification for continuing this experiment – not education (given that this web page is an example of the quality of information SeaWorld provides the public), not research (we are working on evaluating the research SeaWorld has posted on its publications page - http://seaworld.com/en/truth/global-impact/resear... - and we have not identified any work here that justifies the continued captive maintenance of these animals), and not conservation (given that SeaWorld gives less than 1% of its revenue to conservation each year).

It is important to remember one thing: NO ONE cares about the health and well-being of our killer whales as much as we do. 

This is clearly not true, given the debate raging in the public arena on this topic. This comment is in fact insulting to the members of the public, including SeaWorld’s own visitors, who clearly have a strong commitment to the welfare of these animals. 

Conclusion
Discussions of longevity can become surprisingly complex, and it is easy for people to be confused or misled. As we have seen, a careful look at the data supports the view that the survival rates of killer whales at SeaWorld are comparable to those of the wild.
 

This statement is incorrect, as I have demonstrated above.

--

 [1] Olesiuk, P. 2012. Population biology of the resident ecotype of killer whale in British Columbia. Materials of the killer whale workshop, Suzdal, Russia. 

[2] Matkin, C.O., J. Ward Testa, Graeme M. Ellis and Eva L. Saulitis. 2013. Life history and population dynamics of southern Alaska resident killer whales (Orcinus killer whale). Marine Mammal Science: 10.1111/mms.12049 

[3] Small, RJ and DP Demaster. 1995. Survival of five species of captive marine mammals. Marine Mammal Science 11:209-226. 

[4] For a more comprehensive and technical look at the complexity of this subject, see van der Toorn, “Survival Guide to Survival Rates,” Marine Mammals: Public Display and Research, 3(1) 27:38 (June 2000). The paper demonstrates the many pitfalls of comparing wild and captive populations, as well as invalid comparisons between “life expectancy” and “longevity.” It recommended using survival rates instead. 

[5] The Matkin, et al., study excluded whales it believes had been exposed to the Exxon Valdez oil spill. 

[6] “Breeding Male Killer whale in Collapse, Total Down 26% from 2009 – Lowest Count Since 2003,” Killer whale Relief Citizens’ Alliance, Oct. 22, 2013, http://seaworld.com/en/truth/global-impact/resear... whalerelief.org/newsroom.php. A study released the previous month on females produced reported similar findings. http://seaworld.com/en/truth/global-impact/resear... whalerelief.org/research.php