Southern Resident Killer Whale
Roughly half of all Southern Resident killer whales (Orcinus orca) were removed from the population due to shooting prior to 1960 and live capture in the 1960s and 1970s, but once these activities were banned, the population rebounded from 71 individuals in 1976 to 98 in 1995. However, the population has declined since, and as of September 2018 stands at 74, the lowest it has been in 34 years. The prospects for recovery appear bleak, as since 2015 there have been no births that have produced calves who have survived.
Killer whales are found in every ocean, but the species is 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. In the temperate coastal North Pacific, there are three different ‘ecotypes’ of killer whales. The so-called “Resident” killer whales are fish eaters found on both sides of the North Pacific along the coasts. Bigg’s or Transient killer whales are marine mammal hunters and also are found all along the North American coast. The little known “Offshore” killer whales, which feed on schooling fishes and possibly sharks, are found from California to Alaska, mostly along the continental slope, and possibly far out to sea. In the eastern North Pacific, there are three populations of Resident killer whales: Alaska Residents, Northern Residents, and Southern Residents. Southern Residents, which comprise the smallest of the ‘resident’ populations, are found mostly off British Columbia, Washington and Oregon, and occasionally off Alaska or California. Southern Residents are Chinook salmon specialists, feeding on Chinook year-round, especially in the spring and summer when they occupy inland waters and it is their primary prey. During the fall and winter, when they are dispersed 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).
Southern Resident killer whales associate in stable social units called ‘pods.’ Most Southern Residents live their lives within their natal pod and interact with members of other pods several times a year. The three Southern Resident pods (J, K and L) differ in a number of characteristics, including pod size, dialect and home ranges. Within each pod there are several family units, each descended from a single female ancestor. These units, called matrilines, are each typically composed of an adult female, the “matriarch”, and her female and male offspring. In several cases, although the matriarch has died, the family unit has remained together. A few matrilines are functionally extinct as they are composed only of one or more males.
The Southern Resident killer whale population may have numbered more than 200 animals prior to the 20th century. However, with modern impacts on their prey base, opportunistic shooting prior to the 1960s, and the live capture or killing of nearly 70 Resident and Transient killer whales for marine parks and display from 1967 to 1971, the first complete count found just 71 whales in 1976. With the cessation of capture and shootings, the population slowly increased to a peak of 96-98 whales in the mid-1990s. However, in just five years from 1996 to 2001 the population rapidly declined by 20 percent to 78 whales. This population was listed as Endangered in Canada in 2001 by the Committee on the Status of Endangered Wildlife in Canada, and as Endangered in the United States in 2005 under the Endangered Species Act (ESA).
Southern Resident killer whale numbers rebounded to 89 by 2006 and stabilized at 85-89 animals through 2011. However, after 2011 the population again entered a period of decline, and as of late September 2018 stands at just 74 whales. The population was that small last in 1984.
From 1984 to 2011, there were two to six births in the population in most years (average=3.85 per year). However, 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. Unfortunately, no calves were born in 2017, and the one calf born in 2018, by late September, died shortly after its birth. From 2012 to September 2018 there were 12 births (average=2.00 per year), seven of which have survived. Scientists are concerned that the ratio of male to female births has been skewed in recent years. In the last twenty years (1999-2018), there have been 31 known calves born that survived long enough for their gender to be determined. Only eight (26%) of those calves were females. Because a population’s reproductive output is dependent more on the number of females than males, this male-biased sex ratio among the juvenile whales limits the population’s reproductive potential and chance of recovery. Population viability analyses suggest that if reproductive rates remain low then the population is going to continue to decline.
Major concerns for the future of the population are it declining size, low number of births (zero to two) in five of the six years from 2013 through 2018, strong male sex-ratio bias among juveniles, and small population size.
Individuals and Pods:
Among those lost in late 2016 was the whale known as ‘J2’, the matriarch and second known member of the ‘J’ pod. Estimated at over 80 years, she was the oldest known Southern Resident killer whale. As part of photogrammetric studies of Southern and Northern Resident killer whales, John Durban and Holly Fearnbach of the National Marine Fisheries Service reported that she looked thin in the early fall of 2016 just prior to the last time she was seen alive. The effect of the loss of a matriarch is not known, but research has suggested that post-menopausal, female killer whales make important contributions to their pods. They appear to lead the pod, presumably using their accumulated knowledge of the environment to find prey. They also appear to support individuals in other ways, as sons who lose their mothers are three times more likely to die.
In recent years, aerial images taken from micro-copters (small rotary-winged drones) have been used increasingly to assess the body condition and health of cetaceans, including the Southern Resident killer whales. Recently published research found declining body condition in 11 of 59 Southern Resident killer whales photographed in 2008 and 2013, two of whom died shortly after being found in poor condition. In 2018, a young female, J50, was found to be in very poor condition. NMFS and other organizations put together a plan to give her antibiotics and to try to supplement her diet. Antibiotics were administered and she was presented with live Chinook salmon, although it could not be ascertained whether she ate any of them. Unfortunately, her condition did not improve and she was last seen on September 7th. She is now presumed to be dead.
The sizes, trends in numbers, and demographic patterns have differed among the three pods. The dynamics of the largest pod, L Pod, have largely driven the population trends described above. The pod increased to a maximum of 56-59 whales in the mid-1990s, declined to 34 in 2014, and has been steady at 35 whales through 2017. In contrast, the next largest pod, J Pod, increased slowly in size from 16 whales in 1976 to 28 in 2010, fluctuated between 25 and 30 whales through 2016, but then suffered eight deaths through September 2018; there are now 22 whales in the pod. It is this pod that has been responsible for the recent decline in the total population size. The smallest pod, K Pod, has shown only a very slight numerical increase from 14-16 whales from the late 70s through the early 80s, to 18-21 whales since 2000, a growth rate of approximately two percent per year. A healthy population would grow substantially faster. For example, the Alaska Resident killer whale population has been increasing in recent years at a rate of 3.5 percent. While there have been 27 known births in J and L pods in the last 10 years, only one calf, born in 2010, has been seen in K Pod during that period.
In addition, the three pods have different distributions off the West Coast and show different movements during the year, typically tied to the movements of different 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. This pattern has been breaking down 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 suggest that they are spending time near the mouths of major rivers and estuaries, presumably to take advantage of salmon runs taking place in those seasons.
Scientists are uncertain about how many Southern Resident killer whales can currently be supported by the environment. Although the environment’s carrying capacity may have exceeded 200 whales before the 20th century, it may not be able to support that many Southern Resident killer whales now. Like the other fish-eating killer whale populations in the North Pacific, the Southern Residents are dietary specialists on fish, and particularly Chinook salmon. Recent scientific findings suggest that the reproductive and mortality rates of resident killer whales are related to the abundance of Chinook salmon, which has declined significantly from before the era of intense commercial fishing and widespread habitat destruction. Modeling studies suggest the modern carrying capacity is roughly 90 whales, which suggests that the decline since the mid-90s is not due primarily to prey-related, density-dependent factors.
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
For more information on the Southern Resident Killer Whale, see the Commission’s 2010-2011 annual report (pages 95 – 99).
|Letter Date||Letter Description|
|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|
The lack of a sustained recovery and ongoing decline since 2001 may reflect a lower carrying capacity, but many researchers are concerned that human activities and impacts, in addition to those that may have contributed to a decline in carrying capacity, may have prevented the population from fully recovering and are causing the population decline seen in recent years. 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, could be limiting growth and reproduction.
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 DDT, PCBs and flame retardants, all of which are associated with lowered disease resistance and/or decreased reproduction in marine mammals. Most POPs are retained and accumulate in their fatty tissues, increasingly affecting their health over time. More importantly, if a whale encounters a period of low prey abundance, it will mobilize energy in its fat reserves, thus releasing large amounts of these pollutants into its blood stream, which can seriously degrade the whale’s health, affect its reproductive potential and even lead to death. When killer whales give birth they offload a substantial proportion of the POPs they have accumulated to their calf. A female giving birth for the first time is likely to deliver a much larger load than females who have already given birth. A disproportionately high number of first calves die early in life. Recent research that looked at hormone levels in feces (yes, scientists collect whale poop to learn more about their health and diet) found that, between 2008 and 2014, over 2/3 of detectable Southern Resident killer whale pregnancies were unsuccessful, suggesting that the recent fecundity decline in the population is a much more serious problem that it had appeared to be from the decrease in the number of births detected each year. The authors of the study concluded that limited availability of Chinook salmon was the primary cause, while the release of POPs as the mother metabolizes her fat may have been a contributing factor. However, Transient killer whales have even higher levels of POPs in their tissues and are doing well, which suggests that reduced prey availability and other factors are likely more responsible, perhaps cumulatively, for the decline of Southern Residents.
The Salish Sea is busy with boat traffic traveling to and from Vancouver, Seattle and Tacoma, and many smaller ports. That traffic could increase substantially in the future with the construction of a new oil pipeline in British Columbia, which is predicted to result in a roughly seven-time increase in the number of oil tankers passing through key habitat in the San Juan Islands. In April 2017, two Northwest Indian tribes, the Tulalip and Suquamish, sued the U.S. Coast Guard, alleging that they failed to consult with NMFS regarding its traffic-separation scheme for the Strait of Juan de Fuca, and its potential impact on the Southern Resident killer whale population. From August to October 2017, the Port of Vancouver asked ships passing through Haro Strait to slow down. Haro Strait is part of, and adjacent to, critical foraging habitat for Southern Resident Killer Whales. Dozens of shipping and cruise companies complied with the request. Analyses showing the effect of the slowdown on noise levels in killer whale habitat will be published in 2018. Preliminary results showed the greatest noise reductions by the fastest and largest ships. However, it is not likely that large vessels represent the greatest vessel threat to Southern Resident killer whales. Vessels both large (such as bulk/general cargo ships, container ships, and ferries) and small (such as commercial whale watching boats, recreational fishing and other recreational/private vessels) may cause disturbance by their physical presence in proximity to the whales (even if emitting no sounds). Sounds emitted from certain vessels may exacerbate that disturbance, by possibly masking communications of the whales with each other. However, any effect of sound depends on whether the whales can hear the sounds (e.g. engines, propellers, thrusters, or echosounders), which is based on their hearing sensitivity AND the source level and frequencies of the sounds emitted and the vessel’s proximity to the whales. Larger vessels transiting Southern Resident killer whale habitat in the Salish sea emit sounds at frequencies below the hearing sensitivity of killer whales or at source levels lower than (or the distance is too great) generally affect them. These vessels may be using echosounders for navigation which the whales might be able to hear, but these higher frequency sounds do not propagate far and, therefore, to have an impact, the whales must be very close to the vessels. Smaller vessels, especially the commercial and private vessels engaged in whale watching, are more likely to be emitting sounds that the whales can hear (within their hearing sensitivity and at a source level or within a distance that would make them audible), and are more likely to be in closer proximity to the whales. However, the impacts of the sounds still depend on whether the whales do actually hear them (as well as the whales’ behavioral state) and cannot be separated from the impacts of disturbance via the physical presence of the vessels close to the whales.
Research has shown that Southern Resident killer whales have a variety of responses to the presence of vessels, including altering behavior (vessel avoidance and attraction, reduced surface-time / longer dives, increases in the proportion of time spent traveling, increased respiration rate and swimming speed, reduced foraging, disruption/interruption of foraging or traveling) and modulating their vocalizations (increased loudness). In addition, vessels may contribute to an increase in stress hormones when prey is limited. However, these studies have not been able to ascribe the responses specifically to the presence of the vessels or the sounds they generate.
Current Conservation Efforts
Recent modeling suggests that a robust population recovery will require 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. 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
Following ESA-listing of the population, NMFS designated critical habitat in the inland waters of Washington in 2006. In response to a petition received in 2014, NMFS is now revising the critical habitat designation, taking into consideration the coastal areas of the West Coast that are used by Southern Resident killer whales, and important habitat features such as prey availability and anthropogenic sound. However, because NMFS had as of August 2018 not yet proposed the revised critical habitat, the agency has been sued by the Center for Biological Diversity, requesting that NMFS finalize the revised critical habitat designation.
Additionally, in response to a petition, NMFS agreed to include the captive female Southern Resident killer whale known as “Lolita” in the population’s endangered species designation. Lolita, who was captured in 1970, currently resides at the Miami Seaquarium. Of the members of the Southern Resident killer whale population that were captured during the 1960s and 1970s, she is the only one still alive.
In February 2010, NMFS released its five-year action plan for stabilizing the Southern Resident killer whale population. Major initiatives include protecting the whales from harmful vessel impacts, recovery of critical salmon stocks, and protecting critical habitat. In 2015, NMFS identified eight marine species or populations most at risk of extinction, including the Southern Resident killer whale. NMFS announced that it would be focusing its resources on saving these “Species in the Spotlight” from extinction.
In December 2016, NMFS published a new five-year ESA review of Southern Resident killer whales. The review identified new research and conservation efforts that have been undertaken since the implementation of the 2008 Recovery Plan and the 2015 report on research activities, and how they contribute to improved understanding of the population and its recovery. The review concluded that “the overall status of the population is not consistent with a healthy, recovered population”, and that “Southern Resident killer whales remain in danger of extinction.”
In November 2016, three organizations petitioned NMFS to establish a protection zone for the southern resident killer whale population, intended to reduce disturbance of killer whales by vessel traffic and vessel noise. The proposed zone is along the southwest shore of San Juan Island, Washington, a key feeding area, especially for J pod. The petitioners requested that access to the proposed zone by certain vessels be prohibited during the months of April through September, when Southern Resident killer whales typically make use of the area for feeding. In January 2017, NMFS asked for information and comments on: (1) the need for a protection zone, (2) its geographic scope, (3) alternative management options to regulate vessel traffic, (4) effects of vessels on killer whales and their habitat, (5) potential economic impacts, and (6) any additional information that NMFS should consider. The Commission submitted its comments and recommendations regarding the proposed protective zone in March 2017. Its letter included the recommendations that NMFS (1) designate a time-limited Southern Resident killer whale protection zone (e.g. six years) with boundaries that encompass the largest size considered in the petition, (2) prohibit vessel access to the protection zone with certain exceptions, and (3) undertake monitoring studies focused on assessing a) the sources and levels of noise within the protection zone, b) changes in foraging activity and behavior of Southern Resident killer whales in response to protection zone measures, and c) the overall health, reproduction, and abundance of individuals in the Southern Resident killer whale population. As of September 2018 NMFS is withholding its decision on the petition until measures for the protection and recovery of Southern Resident killer whales that have been proposed or are under discussion by San Juan County and the state of Washington are finalized.
Selected Peer-Reviewed Publications
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
Effects of age, sex and reproductive status on persistent organic pollutant concentrations in “Southern Resident” killer whales. Margaret M. Krahn et al. 2009. Marine Pollution Bulletin 58(2009):1522-1529
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