Orca Relief Citizens’ Alliance acts to reduce the mortality rates of cetaceans – particularly of Orcinus orca in the Salish Sea – through research, education and related activities. To that end, one of the main goals of the Orca Relief Citizens’ Alliance is to further scientific knowledge regarding the recent decline of the Southern Resident pod of Orcas.

15 Years of Research Demonstrates That Noise and Disturbance are Significant Factors in the Failure of the Endangered Southern Resident Killer Whales to Recover Their Population Heath

Disturbance and Noise Effects:

Animal behavior and marine protected areas: incorporating behavioural data into the selection of marine protected areas for an endangered killer whale population (E.Ahse, D.P. Noren & R. Williams)  asheetal2010_killerwhaleMPA

Echolocation singles of free-ranging killer whales (Orcinus orca) and modeling of foraging for chinook salmon (Oncorhynchus tshawytscha)
(Whitlow W.L. AuJohn K.B Fordjohn K. HorneKelly A. Newman Allman)

Scientific Synthesis on the Impacts of Underwater Noise on Marine and Coastal Biodiversity and Habitats (Convention on Biological Diversity. 2012)

Stopping or reducing feeding, resting, and social interaction

(Constantine et al. 2004)

Abandoning feeding, resting, and nursing areas

(Bejder et al. 2006; Lusseau 2005; Lusseau et al. 2009)

Altering travel patterns

(Lemon et al. 2006; Lusseau 2003; Mattson et al. 2005; Noren et al. 2009; Williams et al. 2013)

Changes in acoustic behavior

(Erbe 2002; Finneran et al. 2005; Holt et al. 2008, 2011, 2015; Van Parijs & Corkeron 2001; Wieland et al. 2010)

Masking communication signals

(Erbe 2002; Foote et al. 2004; Holt et al. 2009; Jensen et al. 2009)

Increased amounts of stress hormones and changes in metabolic rates

(Holt et al. 2015; Romano et al. 2004)

Disturbance of Resident Killer Whales by Vessels Engaged in Whale Watching:

Short-term behavioral changes in the presence of vessels

(Bain et al. 2006; Bejder et al. 2006; Foote et al. 2004; Holt et al. 2008; Lusseau et al. 2006; Noren et al. 2009; Williams et al. 2002, 2006, 2009; Williams & Ashe 2006)

Swimming faster, adopting less predictable travel paths, making shorter or longer dives, moving into open water, and altering normal patterns of behavior

(Bain et al. 2006; Noren et al. 2009; Williams et al. 2002, 2009)

General issues concerning whale watching and whales

(Ashe 2009; Baird 2000; Erbe 2002; Houghton, et al. 2015; Lusseau 2004)



Houghton, et al. (2015)

The relationship between vessel traffic and noise levels received by killer whales (Orcinus orca). PLOS One DOI:10:1371/journal.pone.0140119

Williams, et al. (2015)

Quiet(er) marine protected areas. Marine Pollution Bulletin 100(1): 154-161

Holt, et al. (2015)

Vocal performance affects metabolic rate in dolphins: implications for animals communicating in noisy environments. Journal of Experimental Biology doi: 10.1242/jeb.122424

Williams et al. (2013)

Severity of killer whale behavioral response to ship noise: A dose response study. Marine Pollution Bulletin 79(1-2):254-260

Holt et al. (2011)

Holt MM, Noren DP, Emmons CK. Effects of noise levels and call types on the source levels of killer whale calls. J Acoust Soc Am 2011; 130(3100-3106).

Wieland et al. (2010)

Changing durations of southern resident killer whale (Orcinus orca) discrete calls between two periods spanning 28 years. Mar Mam Sci 2010; 26(195-201).

Williams et al. (2010)

Killer whale activity budgets under no-boat, kayak-only and power-boat conditions. Contract via Herrera Consulting, Seattle, Washington. 29 pages.

Ashe, et al. (2009)

Animal behavior and marine protected areas: incorporating behavioral data in to the selection of marine protected areas for an endangered killer whale population. Animal Conservation 13:196-203.

Holt et al. (2009)

Speaking up: Killer whales (Orcinus orca) increase their call amplitude in response to vessel noise. J Acoust Soc Am 2009; 125(El27-El32)

Jensen et al. (2009)

Vessel noise effects on delphinid communication Mar Ecol Prog Ser395: 161-175

Lusseau et al. (2009)

Vessel traffic disrupts the foraging behavior of southern resident killer whales, Orcinus orca. Endangered Species Research 6:211-221

Noren et al. (2009)

Close approaches by vessels elicit surface active behaviors by southern resident killer whales. Endangered Species Research 8:179-192

Williams & Noren. (2009)

Swimming speed, respiration rate, and estimated cost of transport in adult killer whales. Mar Mammal Sci 25: 327-350.

Williams et al. (2009)

Effects of vessels on behavior patterns of individual southern resident killer whales Orcinus orca. Endangered Species Research 6: 199-209

Holt et al. (2008)

Noise effects on the call amplitude of southern resident killer whales (Orcinus orca) Bioacoustics 17: 164-166

Williams & Ashe (2007)

Killer whale evasive tactics vary with boat number J Zool 272: 390-397

Bain et al. (2006)

Effects Of Vessels On Behavior Of Southern Resident Killer Whales (Orcinus spp.). NMFS Contract report.

Bejder (2006)

Decline in Relative Abundance of Bottlenose Dolphins Exposed to Long-Term Disturbance. Conservation Biology 20: 1791-1798,

Bejder et al. (2006)

Interpreting short-term behavioural responses to disturbance within a longitudinal perspective Animal Behaviour 72: 1149-1158

Lusseau (2006)

The Short-Term Behavioral Reactions of Bottlenose Dolphins to Interactions with Boats In Doubtful Sound, New Zealand. Marine Mammal Science 22: 802-818.

Williams & Ashe (2006)

Northern Resident Killer Whale Responses to Vessels Varied With Number of Boats. NOAA Fisheries Report.

Williams et al. (2006)

Estimating relative energetic costs of human disturbance to killer whales (Orcinus orca). Biological Conservation 133:301-311

Finneran, et al. (2005)

Temporary threshold shift in bottlenose dolphins (Tursiops truncatus) exposed to mid-frequency tones. Journal of the Acoustic Society of America 118: 2696.

Lemon et al. (2005)

Response of travelling bottlenose dolphins (Tursiops aduncus) to experimental approaches by a powerboat in Jervis Bay, New South Wales, Australia. Biological Conservation 127: 363-372

Lusseau (2005)

Residency pattern of bottlenose dolphins Tursiops spp. in Milford Sound, New Zealand, is related to boat traffic. Mar. Ecol. Prog. Ser. 295: 265-272

Mattson et al (2005)

Effects of Boat Activity on the Behavior of Bottlenose Dolphins (Tursiops truncatus) in Waters Surrounding Hilton Head Island, South Carolina. Aquatic Mammals 31: 133-140

Constantine (2004)

Dolphin-watching tour boats change bottlenose dolphin (Tursiops truncatus) behaviourBiological Conservation 117: 299-307

Foote, et al. (2004)

Whale-call response to masking boat noise. Nature 428: 910

Lusseau (2004)

The Hidden Cost of Tourism: Detecting Long-term Effects of Tourism Using Behavioral Information. Ecology and Society 9.

Romano et al. (2004)

Anthropogenic sound and marine mammal health: measures of the nervous and immune systems before and after intense sound exposure. Can.J.Fish. Aquat.Sci. 61:1124-1134

Lusseau (2003)

The effects of tour boats on the behavior of bottlenose dolphin. Conservation Biology 17:1785-1793

Erbe (2002)

Underwater noise of whale-watching boats and potential effects on killer whales (Orcinus orca), based on an acoustic model. Marine Mammal Science, 18: 394-418

Williams et al. (2002)

Behavioural responses of killer whales (Orcinus orca) to whale-watching boats: opportunistic observations and experimental approaches J. Zool., Lond256: 255-270

Williams et al. (2002)

Behavioural responses of male killer whales to a ‘leapfrogging’ vessel. J Cet Res Mgmt 2002a; 4(305-310)

Van Parijs & Corkeron (2001)

Boat traffic affects the acoustic behaviour of Pacific humpback dolphins, Sousa chinensis Journal of the Marine Biological Association of the UK 81: 533-538.

Ylitalo (2001)

Influence of life history parameters on organochlorine concentrations in free-ranging killer whales from Prince William Sound, Alaska. Science of the Total Environment 281: 183-203

Baird et al. (2000)

Bias and variability in distance estimation on the water: Implications for the management of whale watching. IWC Meeting Document.

Ross et al: (2000)

High PCB concentrations in free-ranging Pacific Killer Whales, Orcinus orca: Effects of age, sex and dietary preference. Marine Pollution Bulletin 40: 504-515.

Orca Relief Citizens’ Alliance asked three independent researchers to find a cause for the Orca decline.

Bain, David: A model linking energetic effects of whale watching to Killer Whale (Orcinus orca) population dynamics.

Kriete, Birgit: Biogenetic changes from 1986 to 2001 in the Southern Resident Killer Whale population, Orcinus Orca.

VanBlaricom, Glenn and Alvares-Flores, Carlos: Evaluation of factors influencing the population dynamics of the Southern Resident population of Killer whales (Orcinus orca [L.]).

The following comments are in our own words, although you will find matching statements in the papers themselves:

The three papers they provided, we believe, extend the good work many of you have started in earlier years; most of the ideas are not too surprising (with a few exceptions), but the results certainly are. While I encourage you to read them in detail, I would like to take a moment to point out three results (one each) which I believe warrant real attention…

  • From the VanBlaricom and Alvarez-Flores paper: Although one cannot correlate death rates in the southern population with fish stocks, water temperature, or boat presence alone, the combination of fish stocks and boat presence provides a strong, statistically-meaningful correlation with population decline.
    Click here to read paper summary
  • From the Bain paper: The presence of the whale watching fleet may be assumed to reduce the whales’ sonar efficiency by 95-99%.
    Click here to read paper summary
  • From the Kriete paper: Even at rest, males in 2001 respired at rates 100 % above those of 1986-7; energy consumption was up 19%.
    Click here to read paper summary

Although you will no doubt come to your own conclusions about what these findings all mean for the southern residents, we have constructed a sentence based upon your work, and this work, which we believe best represents what is known about what is killing these whales:

“In an environment of declining salmon, the presence of the whale watch fleet decreases sonar efficiency by 95-99%, while increasing food requirements; the resulting starvation forces the whales to draw down toxin-laden blubber, and they die.”

Those of you most focused upon the role of toxins will notice that this explanation provides the first rationale explaining how the whales might be increasingly affected by PCBs, even as these have declined over decades in the marine environment.

We feel it is important to share these findings with the scientific community at this time in order to make this information known, and discuss and establish future policies regarding the southern resident killer whale population.

Study Summaries

Dr. David Bain

The southern resident killer whale (Orcinus orca) population declined from 98 to 79 animals from 1995 through 2001. While reduced prey availability and exposure to toxic chemicals are widely accepted as potential contributing factors in the decline, the suggestion that whale watching traffic may also play a role is more controversial. We combined three analytical models with changes in behavior measured in northern residents and approximate levels of whale watching traffic experienced by southern residents to estimate population-scale effects. These effects would result from increased energy expenditure due to avoidance responses and reduced energy acquisition due to acoustic impairment of foraging efficiency. Our models indicate that population-level effects are negligible for killer whale populations well below carrying capacity (K). Thus population growth in the presence of disturbance cannot be used to conclude that disturbance will not affect the population at higher densities.

We demonstrate that missed prey due to noise is potentially a more important mechanism than excess energy expenditure. The high value of the shape parameter (z) of the killer whale population growth model suggests that the maximum net productivity level is over 80% of K, rather than the NMFS default of 50-60%. Similarly, the Potential Biological Removal level calculated with z=1.0 is too high. Southern residents are currently below their maximum net productivity level and should be considered a depleted stock. Any human-induced mortality or serious injury at levels exceeding one individual every 2-10 years needs to be reduced. The best estimate of the effect on carrying capacity of whale watching at current levels is about 3% due to excess energy expenditure, but insufficient data are available to reliably estimate the impact of noise.

Clearly, more data are needed to determine whether the actual impact of whale watching that our models predict exceeds “insignificant levels approaching zero.” However, the precautionary principle supports mitigating potential impacts until data become available to indicate that regulations or guidelines are unnecessary.

Link to full paper

Dr. Birgit Kriete

This study provides a comparison of the physiological changes of the southern resident killer whale population from a period of very little boat traffic to an era of increased marine vessel commerce, and it clearly indicates that boat traffic has a negative effect on the whales. The regular physical activity of the southern whales has increased in recent years. Swimming velocities and respiration rates of the southern whales have shown statistically significant increases since the 1980’s. Increases in respiration rates indicate that the animals are stressed. It appears that the significant environmental change that may contribute to the change in energy expended is the increase in whale watch boat traffic.

The increase in swimming velocity is metabolically very costly. Avoidance behavior carries high energetic costs. Any increase in swimming velocity and respiration rate needs to be balanced by an increase in food consumption in order to pay metabolic debts. With the decrease in salmon stocks, this poses an additional threat to the orcas. If energetic demands cannot be met, females might not be able to satisfy high feeding demands of calves, adipose tissue is reduced, which concentrates the level of toxins in the blubber, and immune systems are weakened.

A decrease in foraging opportunity, increased energetic demands due to boat traffic and noise, a possible disruption of sleep patterns combined with a decrease in food availability and toxic contaminants all can lead to lowered immune functions, decreased fecundity, a decrease in survivorship, starvation, decreases in population size and possibly extinction.

Link to biography for Birgit Kriete
Link to full paper

Dr. Glenn VanBlaricom and Carlos Alvarez-Flores

Survival rates in the southern resident orca (SRO) population were found to vary over time, with different age and gender classes showing different patterns of temporal variation. Survival rates declined most strongly for males and especially old males over the time course of the analysis (1974 through 1999). Survival rate also declined for old females. Calf survival was more variable than any other age or gender category. Despite the suggestion of declining calf survival in the data, however, variance over time was sufficiently high that the apparent temporal trend was not significant.

Of covariates evaluated, boat activity was most strongly correlated with the trends in survival described above, followed by salmon abundance, except that the apparent trend in calf survival was sensitive to the specific model used. Sea surface temperature, a proxy for a number of important environmental processes, did not correlate well with survival trend. Contaminant effects could not be evaluated as a covariate because of the absence of a time series of data. Finally, a simulation analysis indicated that demographic stochasticity alone could explain observed trends in the SRO population at least through 2000. Our analysis suggests the possibility of a combination of anthropogenic factors and random demographic variation are contributors to declines in the SRO population.

Link to biography for Glenn VanBlaricom
Link to biography for Carlos Alvares-Flores
Link to full paper

Researcher Biographies

Birgit Kriete
Executive Director, Orca Relief Citizens\’ Alliance

Dr. Birgit Kriete, Ph.D. brings nearly 20 years of whale research experience in Europe and North America to her position as Executive Director at the Orca Relief Citizens’ Alliance (ORCA). ORCA is a non-profit effort to study and reduce Orca mortality rates.

Kriete obtained her Ph.D. as a whale researcher through the University of British Columbia in Vancouver, B.C. in 1995. Her dissertation was “Bioenergetics in the killer whale, Orcinus orca“. She has been an independent researcher since then.

Her many years of studying whales includes serving as research and education director at The Whale Museum in Friday Harbor, Washington as well as work as a research intern and assistant at the Center for Coastal Studies in Provincetown, MA, where her work included research on right, humpback, finback whales, focusing on prey items of the endangered North Atlantic Right Whale. Kriete also conducted research on the “Killer Whale Population Assessment in Sweden and Norway” through Memorial University, St. Johns, Newfoundland.

Kriete currently resides in Friday Harbor, Washington.

Carlos Alvarez-Flores
Doctoral candidate at the School of Aquatic and Fishery Sciences, University of Washington

Carlos Alvarez-Flores is a Doctoral Candidate at the School of Aquatic and Fisheries Sciences of the University of Washington. He works under the supervision of Glenn VanBlaricom Assistant Unit Leader (Wildlife) of the Washington Cooperative Fish and Wildlife Research Unit. He is also under the supervision of Douglas DeMaster currently Science and Research Director of the Alaska Fisheries Science Center of the National Marine Fisheries Service.

Carlos is a citizen of Mexico where he got his MS degree in Science (Biology). His research interests are directed towards applications for the management of activities that affect marine mammal populations and wildlife in general. He initiated in Mexico many of the now successful cetacean photo – identification efforts. He has also worked as a private consultant for the governments of Mexico, the USA and Greenland. He has also conducted private consulting research for the private sector and for international organizations of different nature such as Greenpeace and the North Atlantic Marine Mammal Commission.

Carlos is expecting to defend in July his dissertation on the incorporation of uncertainty in the management of activities that affect marine mammals utilizing as a case study the problem of dolphin mortality in the tuna fishery of the eastern tropical Pacific Ocean.

Glenn R. VanBlaricom
Associate Professor at the School of Aquatic and Fishery Sciences, University of Washington

Glenn R. VanBlaricom is an Associate Professor at the School of Aquatic and Fishery Sciences, University of Washington (UW), and is the Assistant Unit Leader (Wildlife) of the Washington Cooperative Fish and Wildlife Research Unit. He has a research group of nine currently enrolled graduate students (7 PhD, 2 MS). Five doctoral and five MS students have graduated from the UW Program since it was established in 1993. VanBlaricom has 41 publications in the technical literature and has made 122 formal research presentations, including 49 invited presentations, at professional conferences and university seminars. He has published two books (one technical, one non-technical) on sea otters. He has served two stints (eight years total) on the Board of Governors of the Society for Marine Mammalogy (SMM), is currently a candidate for the office of SMM President-elect, and he is a former member of the Board of Editorial Advisors and Referees of the international research journal Marine Ecology Progress Series.

VanBlaricom received Bachelor of Science degrees in Zoology and Oceanography in 1972 from the University of Washington, and a PhD in Oceanography from the Scripps Institution of Oceanography, University of California, San Diego, in 1978.

The VanBlaricom research group is interested in the conservation biology and trophic and community ecology of marine mammal populations, with particular emphasis on coastal species of the North Pacific Rim and the Arctic region. Among current activities are: studies of predation by harbor seals on depleted salmon populations in Puget Sound and southern coastal British Columbia; studies of beluga whale population dynamics and habitat utilization in Cook Inlet; studies of habitat utilization by belugas and narwhals along the Arctic coast of Canada; population dynamics of killer whales in the Bering Sea, northern Gulf of Alaska, southern British Columbia, and Puget Sound; population dynamics of gray whales in the Russian Far East; interactions of the tuna purse-seine fishery with pelagic dolphin populations in the eastern tropical Pacific; population estimation for minke whales in wintering grounds off Brazil; migratory corridors of humpback whales in the southwest Atlantic; and the community ecology of sea otter populations in Washington. The VanBlaricom group is also involved in coastal benthic ecological studies, including the population biology and conservation genetics of black abalones in California, the effects of disturbance by geoduck fisheries on benthic ecosystems in Puget Sound, and habitat and ecosystem associations of deepwater benthic rockfish populations off the Washington coast.