Vessel Noise Hinders Orcas Food Search
Ships of all sizes traveling near Southern Residents can produce underwater noise that makes it harder for them to find food and communicate.
The ship noise can interfere with echolocation, which is the way orcas find their food. Orcas make a clicking noise (hear it in this recording from the National Oceanic and Atmospheric Administration [NOAA]) that travels through the water and bounces back when it hits something. Their senses are so refined that orcas can distinguish what type of fish they found. When the water is noisy, it’s harder for them to find food, and they may stop hunting in the area.
Even quiet vessels, such as kayaks, reduced the time orcas spent hunting for food by roughly 20 percent,1 which reduces the amount of food they eat. That means Southern Residents spend more energy but find less food. Scientists suggest that Southern Residents can lose several hours of hunting a day because of vessel noise and attempts to avoid vessels.
Echo Sounders and Depth Finders
Adding to the problem are echo sounders and other depth finders, which measure how deep the water is by pushing sound pulses toward the bottom and counting the time it takes for them to bounce back. This noise interferes with the orca’s echolocation. Initial findings from NOAA suggest Southern Residents near the San Juan Islands are exposed to echo sounder noise more than one-third of the time.2
In addition, ships emit noise at powerful low frequencies, which forces Southern Residents to send louder and longer calls to coordinate their movements and communicate about feeding opportunities.3 This too can increase the energy orcas spend searching for food.
Although the probability of oil spills can be low, the risks are high. Researchers believe an oil spill of 4 million gallons north of the San Juan Islands would cover between 22 and 80 percent4 of Southern Resident’s habitat, and kill 12.5 to 50 percent of them.5 Southern Residents are especially vulnerable because there are so few females that can have babies and replenish the population.
The task force developed a set of recommendations to decrease disturbance of, and risk to, Southern Residents from vessels and noise. As a result, new rules were put into place for commercial whale-watching boats. New laws also were passed to limit speed and how close any boat may get to the Southern Residents. Please visit the Be Whale Wise Web site to learn more.
The task force developed several recommendations for reducing vessel noise. Learn more about these recommendations and the progress being made.
Photograph by Alan Niles, Pacific Whale Watch Association
1D. Lusseau, D. E. Bain, R. Williams and J. C. Smith, “Vessel traffic disrupts the foraging behavior of southern resident killer whales Orcinus orca,” Endangered Species Research, vol. 6, pp. 211-221, 200.
2M. Holt, B. Hanson, C. Emmons, J. Houghton, D. Giles, R. Baird and J. Hogan, Using acoustic recording tags to investigate anthropogenic sound exposure and effects on behavior in endangered killer whales (Orcinus orca), 2018.
3A. D. Foote, R. W. Osborne and A. R. Hoelzel, “Whale-call response to masking boat noise,” Nature International Journal of Science, pp. 428, 910, https://doi.org/10.1038/428910a, 2004.
M. Holt, D. P. Noren, V. Veirs, C. K. Emmons and S. Veirs, “Speaking up: killer whales (Orcinus orca) increase their call amplitude in response to vessel noise,” Journal of the Acoustical Society of America, pp. EL27-EL32, 2009.
4A. L. Jarvela Rosenberger, M. MacDuffee, A. J. Rosenberger and P. S. Ross, “Oil spills and marine mammals in British Columbia, Canada: Development and application of a risk-based conceptual framework,” Archives of Environmental Contamination and Toxicology, 2017.
5R. C. Lacy, R. Williams, E. Ashe, K. C. Balcomb III, L. J. Brent, C. W. Clark, D. P. Croft, D. Giles, M. MacDuffee and P. C. Pacquet, “Evaluating anthropogenic threats to endangered killer whales to inform effective recovery plans,” Sci Rep., 2017.
Task Force Recommendations
Establish a statewide, “go-slow” bubble for small vessels and commercial whale-watching vessels within half a nautical mile of Southern Resident orcas.
Establish a limited-entry, whale-watching permit system for commercial whale-watching vessels and commercial kayak groups in the inland waters of Washington State to increase acoustic and physical refuge opportunities for orcas.
Create an annual orca protection endorsement for all recreational boaters to ensure all boaters are educated on how to limit boating impacts to orcas.
Increase enforcement capacity and fully enforce regulations on small vessels to provide protection to Southern Residents.
Discourage the use of echo sounders and underwater transducers within 1 kilometer of orcas.
Implement shipping noise-reduction initiatives and monitoring programs, coordinating with Canadian and U.S. authorities.
Reduce noise from Washington State ferries by accelerating the transition to quieter and more fuel-efficient vessels and implementing other strategies to reduce ferry noise when Southern Residents are present.
Reduce the threat of oil spills in Puget Sound to the survival of Southern Residents.
Coordinate with the Navy in 2019 to discuss reduction of noise and disturbance affecting Southern Resident orcas from military exercises and Navy aircraft.
Revise Revised Code of Washington 77.15.740 to increase the buffer to 400 yards behind the orcas.
Determine how permit applications in Washington State that could increase traffic and vessel impacts could be required to explicitly address potential impacts to orcas.
Suspend viewing of Southern Resident orcas.