SEAWORLD FACT CHECK:
SeaWorld claims that approximately 97% of all known-age orcas in free-ranging populations die before they reach age 50. By this simple trick of only considering known-age orcas, they effectively drop a significant number of individuals out of this calculation – the whales who were first seen as adults based on size or presence of calf (so at least 14-15 years of age) when the study in the northeastern Pacific (Washington state and British Columbia) began in 1973, several of whom are still alive (and are thus at least 66-67 years old).
The AP article cited by SeaWorld in its response and Robeck et al. (2015) (a recent paper written by SeaWorld staff and an employee of the Minneapolis Zoo) both calculated average lifespans from annual survivorship rates (ASR) – the AP reporter calculated 46 years and Robeck et al. 47.7 years. Using ASR to calculate average lifespan is an inaccurate method and should never be used, as it is extremely sensitive to minor changes in ASR (a small percentage change in ASR can add or subtract many years from projected lifespans). In addition, it is only accurate when ASR is the same across age classes, which is not the case with orcas (as with most mammals, orcas have a U-shaped survival curve, where very young and very old animals have lower survivorship than “prime-of-life” adults). DeMaster and Drevenak (1988) cautioned against using this method for calculating lifespans for these reasons. Nevertheless, both the AP reporter and Robeck et al. chose to use this method and then Robeck et al. inexplicably cited DeMaster and Drevenak (1988) to explain their decision.
Using the ASR values derived by the AP reporter and Robeck et al. to calculate average lifespan led to essentially nonsensical average lifespans for captive whales (46-48 years). The oldest captive-born orca ever, Orkid, is about to turn 27 (the next oldest, Kayla, is two months younger than Orkid)1. There are now 25 living captive-born orcas in SeaWorld’s "collection" – about a dozen more have died since the first successful birth in 1985, most much younger than 20. It should be clear even to non-mathematicians that an average lifespan of almost 50 cannot be accurate for a category of whale whose oldest member, living or dead, has yet to reach 30.
SeaWorld’s claim that the survival rates for free-ranging and captive orcas are the same is based on a comparison with the northeastern Pacific resident whales, in Washington state and British Columbia. These populations are the best-studied of all free-ranging orca populations and are the basis for most of what we know about this species’ life history traits (Ford 2009). Both of these populations have been struggling in the past decades, starting in the 1960s and 1970s, when SeaWorld and others removed an entire generation of whales for display, but then continuing into the 90s and 2000s when food shortages and pollution became major threats. The Washington state population (the southern residents) is listed as endangered under the US Endangered Species Act2; the British Columbian population (the northern residents) is listed as threatened under the Canadian Species at Risk Act3. Therefore, SeaWorld is basically claiming that its captive orcas are doing only as well as free-ranging orca populations that are at risk of extinction and are struggling with manifold threats. In short, living in captivity appears to be as stressful and dangerous for orcas as living in degraded natural habitat after being depleted by captures a generation ago.
The "studies" SeaWorld references are in fact newspaper stories. Media articles and quotes are not peer-reviewed science. The latest peer-reviewed science, including Robeck et al. (2015), shows that at best captive orcas survive only as well as endangered and threatened orcas and at worst do not survive as well to age “milestones,” in this case sexual maturity and the end of reproduction in females (known in humans as menopause) (Jett and Ventre 2015). In the free-ranging populations in the northeastern Pacific, even in the face of many threats, up to 80% of the whales reach sexual maturity (about 14-15 years of age) and up to 45% reach menopause (about 35-40 years of age). In captivity to date, only 45% have made it to sexual maturity and only 7% have reached menopause.
SeaWorld states that “As concluded in some of the most recent peer-reviewed studies, the leading scientific experts find that for the Resident killer whale ecotype in this area, the average life expectancy for males is 19 years and for females is 30 years. For Residents off the Alaskan coast, observations indicate that the maximum longevity for males appears to be into their 30s and for females appears to be into their 50s.” This statement is incorrect. The average life expectancy for males of the resident killer whales in the northeastern Pacific is 30 years and for females is 50 (Ford 2009). The values SeaWorld presents are for these whales during a decade of elevated mortality due to catastrophic salmon crashes along the Pacific coast of North America (Olesiuk et al. 2005). Again, SeaWorld is basically claiming that its captive orcas are doing only as well as free-ranging whales facing famine! As for the values SeaWorld presents for the residents off Alaska, it is unclear where it got these numbers. Alaskan whales have even higher survivorship rates than the residents off British Columbia during good salmon years (Matkin et al. 2014).
DeMaster, D.P. and Drevenak, J.K. 1988. Survivorship patterns in three species of captive cetaceans. Marine Mammal Science 4: 297-311.
Ford, J.K.B. 2009. Killer whale. pp. 650-657. In: W.F. Perrin, B. Wursig, and J.K. Thewissen (eds.) Encyclopedia of Marine Mammals (2nd edition), Academic Press: New York, NY. 1316 pp.
Jett, J. and Ventre, J. 2015. Captive killer whale (Orcinus orca) survival. Marine Mammal Science DOI: 10.1111/mms.12225
Matkin, C. O., Testa, J. W., Ellis, G. M., and Saulitis, E. L. 2014. Life history and population dynamics of southern Alaska resident killer whales (Orcinus orca). Marine Mammal Science 30: 460-479.
Olesiuk, P.F., Ellis, G.M., and Ford. J.K.B. 2005. Life history and population dynamics of northern resident killer whales (Orcinus orca) in British Columbia. Canadian Science Advisory Secretariat Research Document 2005/045, 75 pp.
Robeck, T. R., Willis, K., Scarpuzzi, M. R. and O’Brien, J. K. 2015. Comparison of life-history parameters between free-ranging and captive killer whale (Orcinus orca) populations for application toward species management. Journal of Mammalogy DOI:10.1093/jmammal/gyv113.
“why has over 90% of your female orcas died before the age of 25? They are supposed to live well into their 80’s?”
Most killer whales don’t live to 80. In fact, approximately 97 % of all known age killer whales die before they reach age 50. The Annual Survival Rates for studied wild killer whales and those born at SeaWorld are the same. Our oldest whale, Corky, is almost 50 and we hope she lives to 80 and beyond.
Where did you get your independent research about how long killer whales live?
Click here for the Wall Street Journal article we mention and here for the Associated Press (AP) story.
“how long do orcas live in the wild?”
The issue of killer whale lifespan is one that is consistently misconstrued and overly simplified.
A small percentage of the overall population of killer whales, the killer whales of the Pacific Northwest, has been the subject of scientific study since the early 1970s. As concluded in some of the most recent peer-reviewed studies, the leading scientific experts find that for the Resident killer whale ecotype in this area, the average life expectancy for males is 19 years and for females is 30 years. For Residents off the Alaskan coast, observations indicate that the maximum longevity for males appears to be into their 30s and for females appears to be into their 50s. Studies continue, and as additional years of observation are recorded and other populations and ecotypes of killer whales are scrutinized by the scientific community, our understanding of killer whale longevity is expected to become more refined.
SeaWorld has several killer whales in their 30s and one that is close to 50 — right in line with what is seen in the wild. In fact, a July 2014 Associated Press (AP) report analyzing 50 years of data from the federal Marine Mammal Inventory Report found that killer whales born at our parks “had an average life expectancy of 46 years.”
Scientists have confirmed that Annual Survival Rate (an estimate of the percentage of whales in a population expected to survive each year) comparisons are more scientifically accurate than comparing life expectancies between wild and captive whales. Recent research tells us that there is no significant difference between the annual survival rates of our whales and the annual survival rates of wild populations.