Longevity & Causes of Death

Longevity

Survivorship in the wild. Different methods exist for estimating the life spans of killer whales. While some researchers believe they know conclusively how long killer whales live, the scientific community does not yet fully agree on this topic. By counting growth layers in teeth, scientists find that killer whales in the North Atlantic may live to 35 years. Studies are still refining this method of aging.

The photo-identification of killer whales in the Pacific Northwest began in 1973 and provides one of the longest cetacean field studies ever. When factored in at birth, the average life expectancy of southern and northern resident killer whales is about 29 years for females and 17 years for males. If a killer whale survives the first six months, a female's average life expectancy is within the range of 46 to 50 years and a male's is 30 to 38 years.

Survivorship in marine life parks. New research shows there is no difference in life expectancy between killer whales born at SeaWorld and a well-studied population of wild killer whales. Data collected on life-history parameters of known-age animals from the northern (NR) and southern resident (SR) killer whales of the eastern North Pacific were compared with life-history traits of killer whales located at SeaWorld (SEA) facilities. Annual survival rate (ASR) for SEA increased over approximately 15-year increments with rates in the most recent period (2000-2015 ASR: 0.976) improved over the first 2 periods of captivity (1965-1985: 0.906; 1985-2000: 0.941). The survival rate (SR) (0.966) and ASR for the combined data for both the southern residents and whales of the eastern North Pacific (0.977) were higher than that of SEA until 2000, after which there were no inter-population differences. Based on ASR, median and average life expectancy were 28.8 and 41.6 years (SEA: 2000-2015), 20.1 and 29.0 years (SR), and 29.3 and 42.3 years (NR), respectively. The ASR for animals born at SEA (0.979) was higher than that of wild-caught SEA animals (0.944) with a median and average life expectancy of 33.1 and 47.7 years, respectively. These data present evidence for similar life-history parameters of free-ranging and captive killer whale populations and the reproductive potential and survivorship patterns established herein have application for use in future research concerning the overall health of both populations. Currently at SeaWorld, five killer whales are older than 30 with one being close to 50. At SeaWorld parks, animal trainers routinely take a variety of measurements — including length, girth, and fin height — of killer whales. For a whale born at SeaWorld, experts are able to relate these measurements to the known age of the whale. This information helps provide a baseline for growth studies on wild killer whales.

Killer Whales

Calf survivorship. For unknown reasons, researchers suspect killer whale calf mortality within the first six months to be "very high". In the Pacific Northwest, for example, an estimated 43% of all calves die in the first six months. In other killer whale populations, calf mortality may be as high as 50% during the first year. Data collected on life-history parameters of known-age animals from the northern (NR) and southern resident (SR) killer whales of the eastern North Pacific were compared with life-history traits of killer whales located at SeaWorld (SEA) facilities. Average calf survival rate to 2 years of age for SEA animals (0.966) was significantly greater than that for SR killer whale populations (0.799).

Diseases, Parasites, and Predators

Killer whales and other whales develop stomach ulcers, skin diseases, tumors, heart disease, and respiratory disorders.

Hodgkin's disease has been seen in killer whales and stranded killer whales have shown severe atherosclerosis of the coronary arteries.

Recently described disease conditions include Salmonellosis in a neonatal stranded calf and West Nile Virus in an adult. Endogenous retroviruses have also been documented within the killer whale genome. The significance of these viruses on the health of killer whale populations is yet unknown.

Killer whales suffer from viral, bacterial, and fungal infections.

Killer Whale
Killer Whales

Parasites — including roundworms, tapeworms, and flukes — may affect a killer whale's health. In most cases, parasite infestations alone are unlikely to debilitate otherwise healthy animals, but they may harm animals that are already weakened by other illnesses or injuries.

Killer whales in New Zealand have evidence of small, non-fatal cookiecutter shark bites in their skin.

Killer whales are a top predator. Healthy adult killer whales have no natural predators of note.

Stranding

A marine animal may strand if it is affected by a severe, debilitating illness or injury, or if it is too weak to swim or hunt for food.

Killer whales have stranded in Alaska due to rapidly receding tides.

On rare occasions, killer whales strand, individually or in groups (called mass stranding). Mass strandings of whales and dolphins are natural phenomena that are largely unexplained. In many cases, the stranded animals are ill.

SeaWorld has helped in the rescue of many types of cetaceans, including killer whales. SeaWorld aided killer whales trapped in Barnes Lake, Alaska, and was part of the team that helped "Springer", an orphaned two-year-old found off Canada's northern Vancouver Island in 2002. SeaWorld assisted the Dolfinarium in Holland with veterinary care and husbandry for an orphaned and hearing-impaired rescued juvenile killer whale.

Killer Whale
Killer Whale
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