Are Orcas Endangered? Conservation Status and Threats

The orca, also known as the killer whale, is the largest and perhaps most recognizable species in the Delphinidae family. These creatures are highly intelligent—so intelligent, in fact, that they have even been observed learning to communicate like other dolphin species.

Despite how iconic these massive mammals are, orcas are incredibly different to study in the wild. They are classified as “Data Deficient” by the International Union for Conservation of Nature (IUCN), meaning that there isn’t enough information on population or distribution to make an accurate assessment of their conservation status. (The only exception is in the case of a small subpopulation of orcas living in the Strait of Gibraltar; they are listed as "Critically Endangered" by the IUCN.)

Here, we explore whether orcas are endangered and the threats they face.

Protections for Orcas

As marine mammals, all orcas are protected under the Marine Mammal Protection Act (MMPA). Although all orcas are generally considered to fall under one species, there are several populations (or “ecotypes”) with independent prey preferences, dialects, and behaviors that differ in size and appearance. Ecotypes are not known to interbreed with or even interact with one another, though they often share overlapping habitats.

There are two distinct populations protected under federal law: the southern resident population that ranges from central California to southeast Asia (considered endangered by the Endangered Species Act), and the AT1 Transient subgroup in the eastern North Pacific (considered depleted by the MMPA).

According to the National Oceanic and Atmospheric Administration (NOAA), the AT1 transient population has been reduced to just seven individuals, while the southern resident population numbers about 76. Estimates place the worldwide orca population at about 50,000 individuals left in the wild, based on 2006 surveys.

The Southern Resident Population

The southern resident population of killer whales was first proposed as an addition to the Endangered Species Act in 2001, after the Center for Biological Diversity petitioned the federal government to conduct a review of the ecotype. Historically, the population had lost an estimated 69 animals to live capture for use in marine mammal parks between the 1960s and 1974. This reduced numbers from about 140 individuals to 71.

Initially, the biological review team determined that the southern resident killer whales warranted “threatened” status, but later changed it to “endangered” following a peer review process in 2015. The last determination of population size occurred in 2017, when biologists documented a total of 76 individuals.

Threats

In the 2013 assessment, the IUCN estimated that the combination of prey depletion and ocean pollution could lead to a 30% reduction in orca populations over the next three generations. Pending more scientific research, these groups could be designated as individual species in the future.

While chemical pollution and prey depletion represent the biggest threats to orcas, other factors, such as noise pollution, capture, and hunting, are also keeping populations down.

Chemical Pollution

Contaminants that enter the ocean from wastewater plants, sewers, or pesticide runoff affect orcas in more ways than one. After entering the environment, these chemicals can harm orca’s immune systems and reproduction systems directly, but also contaminate their prey sources. Considering how long orcas live (from 30 to 90 years old in the wild), chemical pollution can affect these animals for decades.

For example, the Exxon Valdez oil spill of 1989 is still linked to substantial orca loss to this day. A study in the Marine Ecology Progress Series found that killer whales in Prince William Sound, Alaska (the epicenter of the spill), had still not recovered 16 years later. One pod lost 33 individuals during that time, and another’s population decreased by 41%. 

Levels of polychlorinated biphenyl (PCB), or chemicals from industrial waste, continue to threaten the long-term viability of more than half of the world’s orca populations. Though PCBs were banned in 1979, the harmful chemicals are continually found to be present in ocean water and orca tissue samples.

Even worse, mother killer whales contaminated with PCBs can transfer the contaminants to their young, which is detrimental to their development and puts them at greater risk for health defects. The southern resident and transient orca populations have some of the highest PCB levels of all cetaceans.

Noise Pollution

Killer whales use sound to communicate, travel, and feed themselves. Noise from ocean vessels can interrupt these abilities or force them to call louder, which causes them to expend more energy. Whale-watching boats can disrupt foraging and resting if they approach too closely, while fast-moving boats present the risk of vessel strikes.

A study of free-ranging killer whales off the coast of Puget Sound found that orcas increase their call amplitude by 1 decibel for every 1-decibel increase in background noise from motorized vessels. This vocal adjustment was linked to increased stress levels and decreased communication among other pod members.

Prey Depletion  

As predators at the top of their food chains, overfishing and habitat loss can cause serious declines in the amount of food available to orcas. What’s more, many populations of killer whales have highly specialized diets, like the southern resident killer whale, which feeds primarily on endangered Chinook salmon. The impacts of depleted food resources aren’t limited to starvation, either, as the probability of calving among southern resident females is 50% lower when salmon are in low abundance.

Similarly, orcas who call the Strait of Gibraltar home feed off endangered bluefin tuna, following their migration patterns and even interacting with drop-line fisheries to find food. Like Chinook salmon, bluefin tuna is of high commercial value to fisheries.

Capture and Hunting

Capturing killer whales for aquarium displays or marine parks is no longer legal in the United States, but it still occurs in other parts of the world. According to the IUCN, there were at least 65 killer whales live captured between British Columbia and Washington between 1962 and 1977, and 59 captured off Iceland between 1976 and 1988.

The IUCN estimated that of the 21 killer whales caught in the Sea of Okhotsk from 2012 to 2016, at least 13 were exported to Chinese marine parks or aquariums. Killer whales are also hunted deliberately, sometimes by fishermen who see them as competition for fishing, and even for food. From the late 1930s to 1981, whalers in Japan killed an average of 43 orcas each year, while Norwegian whalers took an average of 56.

The ethics regarding captive orcas has gained a great deal of attention over the past few years, and as recently as 2020, the Journal of Veterinary Behaviour explored the harmful effects. The study followed a male adult wild-born orca continuously for 24 hours a day, for seven days straight, at Seaworld Florida, noticing that he spent an average of more than 69% (16.7 hours) of the day inactive. In comparison, orcas in the wild spend over 99% of their lives moving.

Captive-born orcas who are separated from their mothers early exhibited dysfunctional social structures such as inbreeding and reproductive defects as well. Orcas in the Loro Parque facility in Spain have given birth to calves at much younger ages than they would in the wild, under eight years old, compared to the average 11 to 17 years old. One female was impregnated again just four months after giving birth, while 90% of females in the wild have babies only every three to seven years.

Conservation Efforts

Due to their long lifespans, wide range, position on the food chain, and susceptibility to pollution, scientists view orcas as an indicator species that represents the health of ocean ecosystems as a whole.

As indicated by the orca’s designation as “Data Deficient” by the IUCN, further research on orca biology and behavior is imperative to better understand these giants. NOAA is currently working on projects involving satellite tagging, tracking, biological samples, and measuring pollutants, among others. It is also important to understand and identify which salmon or tuna populations overlap with orcas in order to target conservation efforts accordingly.

Orca conservation should highlight the protection of the species itself but also the conservation of its prey and habitats. NOAA accomplishes this by designating critical habitats for vulnerable populations, creating laws that protect orcas from whale-watching harassment and vessel strikes, implementing salmon and tuna recovery, preventing oil spills, and improving response to ocean pollution.