Southern Resident Killer Whale
Killer whales are found in every ocean, but they are segmented into many small populations, at least two of which are likely separate species, that differ genetically, as well as in appearance, behavior, social structure, feeding strategies and vocalizations. The so-called “Resident” killer whales are fish eaters found along the coasts on both sides of the North Pacific. In the eastern North Pacific, there are three populations of Resident killer whales: Alaska Residents, Northern Residents, and Southern Residents. The Southern Residents, which comprise the smallest of the ‘resident’ populations, are found mostly off British Columbia, Washington and Oregon, but also travel to forage widely along the outer coast. Southern Residents are Chinook salmon specialists. They feed on Chinook year-round, and it is their primary prey in spring and summer when they occupy inland waters. During the fall and winter, when Southern Residents disperse widely, they add other salmon species (Coho in fall and chum in winter) and some demersal fishes to their diet (e.g., halibut and lingcod). Resident killer whales associate in stable matriarchal social units called ‘pods’. There are three pods for Southern Resident killer whales, called the J, K, and L pods.
Abundance and Trends
The total abundance for the Southern Resident killer whale population was officially revised in July 2021, standing at at only 74 whales. However, while the population still currently sits at 74 whales, there has been one birth and one whale presumed dead as of July 2023 . The first complete count of Southern Resident killer whales, which took place in 1974, found 71 whales. The population increased to its peak of 96-98 whales in the mid-1990’s following the cessation of killings and captures for marine parks, which stopped after the Marine Mammal Protection Act was enacted in 1972. The Southern Resident killer whales have produced a variable number offspring in recent years. From 2012 to 2014 there were just four births in total (average = 1.33 per year). Somewhat encouragingly, in 2015 seven calves were documented, which was the second largest, single-year number of births on record. Unfortunately, there have been a low number of calf births in recent years. From 2012 through 2020, there were 17 births (average= 1.9 per year), six of which have gone missing or died. During that same period, an additional 26 Southern Resident killer whales have gone missing or died.
The three Southern Resident killer whale pods have different distributions off the West Coast and show different movements during the year, typically tied to the movements of the various runs of Chinook and other salmon. During the summer and fall, when all three pods have typically been present much of the time in Washington’s and British Columbia’s inland waters north and west of Puget Sound, K and L pods often travel to the outer coasts of Washington and Vancouver Island for a few days at a time. Their seasonal distribution has changed in recent years, with the whales spending significantly less time in inland waters in 2013, 2016, 2017 and 2018. In early fall, J pod regularly includes the waters of Puget Sound within their foraging range. From late fall through spring, all three pods apparently spend the bulk of their time on the outer coast, ranging from San Francisco to Southeast Alaska. J and K pods, but rarely L pod, make short excursions to inland waters during this period. Although relatively little is known about their distribution during this time, recent evidence suggests that they are spending time near the mouths of major rivers and estuaries, presumably to take advantage of salmon runs during those seasons.
For more of the historical demographics and details on notable individuals visit the Southern Resident Killer Whale Population Details page.
Responding to a Continued Decline
The ongoing decline of the Southern Resident killer whale population over the last 20 years is most likely due to three distinct threats: decreased quantity and quality of prey, the presence of persistent organic pollutants, and disturbance from vessel presence and noise. In addition to federal conservation action by the National Marine Fisheries Service and Canada’s Department of Fisheries and Oceans, the state of Washington has dedicated considerable effort to reducing the threats faced by the whales. In 2018, Washington Governor Inslee created the Southern Resident Killer Whale Task Force to assist the state in identifying, prioritizing and supporting the implementation of an action plan for the recovery of Southern Resident killer whales. At all levels of government, stakeholders are working to reduce impediments to salmon recovery, decrease inputs of pollutants to the marine system, and manage vessel activity in their preferred habitat. Additional information on threats facing Southern Resident killer whales and their conservation can be found in the Learn More tab.
What the Commission Is Doing
The Marine Mammal Commission has long been concerned about the fate of Southern Resident killer whales, hosting the first workshop focusing on killer whales in Seattle in April 1975. The Commission has consulted with and assessed each of the steps taken by the National Marine Fisheries Service (NMFS) to promote the recovery of the population, and has provided recommendations to NMFS for improvements to their efforts. Some of the Commission’s recommendations have been to:
- Make monitoring of population status a high priority recovery action;
- Make monitoring and evaluation of the effectiveness of recovery actions a high priority;
- Recognize natural sound characteristics as an essential feature of the critical habitat of Southern resident killer whales;
- Implement a precautionary approach with regard to management of contaminants to prevent them from entering the Puget Sound environment;
- Conduct research into habitat use during the winter by Southern Resident killer whales;
- Develop regulatory provisions to establish vessel stand-by zones around Southern Resident killer whales beyond the 200-yard approach limit (e.g., beyond 400-600 yards) and limit the number of vessels that can be present between that boundary and the 200-yard approach limit at any one time;
- Adopt a regulatory speed limit of either seven knots or, at a minimum, a “slow safe speed” requirement within 400 yards of killer whales;
- Develop a monitoring plan to assess compliance with and effectiveness of vessel-approach regulations; and
- Include implementation of a “no-go” zone off the west coast of San Juan Island.
In May 2018, the Commission held its annual meeting in Seattle, and Southern Resident killer whales were a primary focus of the meeting. Issues such as the population’s current status and trends, the factors affecting its health and viability, research being conducted on it, and conservation/management efforts being taken on its behalf, were on the agenda.
Commission Reports and Publications
See the Southern Resident killer whale sections in chapters on Species of Special Concern in past Marine Mammal Commission Annual Reports to Congress.
|Letter Date||Letter Description|
|December 31, 2019||
Letter to NMFS regarding the scoping of potential regulations to protect Southern Resident killer whales from the impacts of vessel disturbance and sound in the inland marine waters of Washington State
|December 18, 2019|
|October 29, 2018|
|October 5, 2018|
|August 30, 2018|
|March 31, 2017|
|August 13, 2013|
|February 4, 2013|
|January 15, 2010|
|March 2, 2007|
|August 14, 2006|
|March 22, 2005|
Since the 1990s, as the abundance of Chinook salmon has declined, the whales have been moving about more to find the hundreds of thousands of salmon they require each year. Declines in the abundance of many stocks of Chinook salmon, their preferred prey, may be causing malnutrition, limiting growth, and complicating reproduction. Greater numbers of deaths and fewer birth have been correlated with lower availability of Chinook salmon. Several whales who have died recently were observed be in poor body condition, perhaps related to poor nutritional status.
Southern Residents spend much of their lives in inland waters near numerous sources of pollutants that accumulate in the fish they consume. Some researchers have argued that calf and juvenile deaths, delayed breeding, and now a skewed sex-ratio in calves, may be related to the effects of persistent organic pollutants (POPs) that have accumulated in the fatty tissues of the whales. Southern Resident killer whales have been shown to have high tissue levels of pollutants that are associated with lowered disease resistance and/or decreased reproduction in marine mammals. If a whale encounters a period of low prey abundance, it will mobilize energy in its fat reserves, thus releasing those pollutants into its blood stream, which can degrade the whale’s health, affect its reproductive potential and even lead to death. A recent study found that between 2008 and 2014 over 2/3 of detectable Southern Resident killer whale pregnancies were unsuccessful. The authors of that study concluded that limited availability of Chinook salmon was the primary cause, while the transfer of POPs from the mother to the calf through breast milk may have be a contributing factor to the poor calf and juvenile survival rate.
Vessels are prevalent in the Salish Sea, traveling to and from Vancouver, Seattle, Tacoma, and many smaller ports. Vessel traffic is predicted to increase with future development projects and greater numbers of oil tankers passing through Southern Resident killer critical habitat in the San Juan Islands. Vessels both large (such as cargo ships, container ships, and ferries) and small (such as commercial whale-watching boats, recreational fishing vessels, and other recreational/private vessels) can cause disturbance based on their physical presence in proximity to the whales. In addition, sound emitted from certain vessels may exacerbate that disturbance by masking communications among the whales. Smaller vessels, especially the commercial and private vessels engaged in whale watching, emit sounds within the hearing range where whales are more sensitive and are likely to be in closer proximity to the whales.
Research has shown that Southern Resident killer whales exhibit a variety of responses to the presence of vessels, including altering their behavior (vessel avoidance and attraction, reduced surface time and longer dives, increased time spent traveling, increased respiration rate and swimming speed, reduced foraging, disruption and interruption of foraging or traveling) and modulating their vocalizations (increased loudness). In addition, the presence of vessels may contribute to an increase in stress hormones when prey is limited. The various studies also have concluded that the physical presence of the vessels cannot be separated from the sound that they generate, making it difficult to determine whether the vessels themselves or the sound that they emit disturb the whales.
Current Conservation Efforts
Recent modeling suggests that a robust population recovery can be achieved with an increase in the abundance and availability of their preferred prey, Chinook salmon, and a reduction in the amount of disturbance and noise from boats and ships. Both of these remedies are possible within a few years, while reducing contaminants, which will be much more difficult to achieve in time to arrest the population decline. Consistent with these findings, NMFS is undertaking a suite of management and research activities designed to enhance the recovery of the population. Those activities include:
- Implementation of vessel regulations and guidelines
- Support of salmon restoration efforts
- Oil spill response preparation
- Studies to improve understanding of the impacts of anthropogenic sound
- Public outreach and education
- Studying year-round movements and diets
- Conducting stranding investigations and health assessments
- Monitoring the population trend
In addition to efforts being undertaken by NMFS, the state of Washington is implementing its own conservation efforts under the leadership of Governor Jay Inslee. In 2018, Governor Inslee issued an executive order that established the Southern Resident killer whale Task Force to assist the state in identifying, prioritizing and supporting the implementation of an action plan for the recovery of Southern Resident killer whales. Along with other government agencies and a wide range of public stakeholders, the Commission provided the Task Force with feedback on its draft report and recommendations. The Task Force released its final report with recommendations in mid-November, and those recommendations are reflected in the Governor’s budget and policy priorities. The Task Force made recommendations designed to increase the availability of Chinook salmon to Southern Resident killer whales, and decrease the risk to the whales from vessels, noise and contaminants.
For more information on NMFS and Washington state conservation efforts visit our Southern Resident Killer Whale Conservation and Management page.
Selected Peer-Reviewed Publications
Unprecedented biennial pattern of birth and mortality in an endangered apex predator, the southern resident killer whale, in the eastern North Pacific Ocean. Gregory T Ruggerone et al. 2019. Marine Ecology Progress Series 608:291-296
Population growth is limited by nutritional impacts on pregnancy success in endangered Southern Resident killer whales (Orcinus orca). Samuel K. Wasser et al. 2017. PLoS ONE 12(6): e0179824. https://doi.org/10.1371/journal.pone.0179824
Review of Recent Research on Southern Resident Killer Whales (SRKW) to Detect Evidence of Poor Body Condition in the Population. Matkin, CO, MJ Moore, and FMD Gulland. 2017. Independent Science Panel Report to the SeaDoc Society. 3 pp. +Appendices. DOI 10.1575/1912/8803