In my current position as a Land-based Marine Educator with Cetus Research and Conservation Society – and as a budding scientist with a deep interest in effective scientific communication – a role of mine is to help people understand scientific information. When I first started reading scientific papers, I was completely confounded; admittedly, more often than not I still only skim the dreaded statistics section. However, in this next series of blog posts I hope to shed light on some of the conservation issues we face in British Columbia through literature reviews and in the process, make some scientific data more accessible to our followers.
You may have heard that concerns about the effects of underwater noise on cetacean (whales, dolphins, and porpoises) health have been steadily increasing. But why?
While humans navigate our world primarily through sight, and dogs use an acute sense of smell, cetaceans depend predominantly on sound. Not only do they use sound to navigate through their visually dark environments, they use sound for foraging, communication, and reproduction. Given that ambient – or background – levels of noise in the oceans have doubled every decade for the past few in many areas, one can see why this is becoming a growing concern (McDonald et al. 2006).
Odontocetes (toothed whales) use sounds at mid to high frequencies (1kHz to 200kHz) and also use echolocation with the help of a complex organ in their head called the melon. Mysticetes (baleen whales) use sounds at low frequencies (0.1 kHz – 1kHz) and do not possess echolocation capabilities (Ocean Conservation Research 2015). Mysticetes calls can travel over hundreds of kilometers! Given that they are so dependent on this sense, concerns surrounding hearing loss, as one example, are a serious conservation concern.
The above image depicts the location of the melon organ which aids toothed whales in echolocation, and the areas where incoming and outgoing sound waves interact with the skull. Image from: http://hoopermuseum.earthsci.carleton.ca/cetaceans/echoloca.htm.
All sorts of human activity generates underwater noise including: seismic testing and subsequent offshore drilling, military and private sonar, and of course any kind of vessels on the water whether its oil tankers, ice breakers, international shipping vessels, recreational vessels, commercial fishing vessels, or commercial whale watching vessels (NOAA 2014). Even pile driving for wind turbines creates noise levels that could be harmful to cetaceans (Thomsen et al.,. 2006). Increasing levels of sound pollution in the oceans have been coined ‘acoustic smog’ due to increasingly adverse effects on cetacean sensory and behavioural health (Bode et al. 2009; Natural Resource Defense Council 2011).
To date, there has been a substantial amount of research done in order to assess the effect that underwater noise has on cetacean health. It can be very difficult to determine just how much of the sound released from a given source actually reaches the animal directly (Williams et al. 2014). Subsequently, it is challenging for researchers to determine exactly how much noise is too much noise and thus a conservation concern. However, the following list outlines some of the determined negative effects that underwater noise can have on cetaceans:
- Killer whales (Orcinus orca) use echolocation and other forms of acoustic communication to forage for salmon; vessel disturbances can interfere with these signals (Weilgart 2007; Holt 2008)
- Many cetaceans have been shown to travel more, forage less, and do more energy inefficient surface displays, particularly when too many vessels too close (Williams et al. 2006; Williams and Ashe 2007; Noren et al. 2012)
- Northern resident killer whales will sometimes alter their direction of travel and their behaviour due to the presence of small vessels (Lusseau et al. 2009; Williams et al. 2006)
- Vessel noise can elevate and prolong stress levels (Wright and Highfill 2007)
- Vessel noise can increase the risk of ship collisions and decrease hunting and feeding efficiency (Aguilar Soto et al.,. 2006; Rolland et al.,. 2012; Erbe and Farmer 2000)
- Killer whales can change the length and loudness of their calls to account for ambient noise, but it has not been shown whether or not they can change their echolocation patterns to compensate for this (Williams et al. 2014)
- Research found that noise from vessels 400 meters away can affect the effectiveness of whales’ echolocation tactics (NOAA 2014)
- Mass Beaked whale (Hyperoodontidae) deaths have been attributed to a combined behavioural and physiological response to increased amounts of human-induced underwater noise (Cox et al. 2006)
- Resident killer whales (Morton and Symonds 2001) and gray whales (Eschrichtius robustus) (Jones et al. 1994) have been known to displace themselves from noisy areas, even if they are part of a habitat that is critical to their lives
As cetaceans are increasingly finding themselves in areas heavily impacted by anthropogenic activities, we must continue to find ways to minimize our impacts on them. Image from: http://www.bbc.com/news/magazine-19179554.
Scientists’ predominant goal is to rule out a single cause and effect mechanism for a given natural phenomenon. In other words, we want to find evidence of a linkage between a single ‘event’ and a single cause. This is the scientific method. In terms of underwater noise, it can be very difficult to isolate its effect on cetaceans. As well, it may often be the case that on it’s own, underwater noise may not pose a severe threat to an animal, population, or species’ survival. However, when taken in combination with all of the other stresses in an animals’ environment, underwater noise can have a very serious effect. For example, a Killer whale may experience levels of underwater noise that may not be harmful on its own, but if it causes it to forage more erratically or less altogether, expending more energy than it would otherwise, and the whale is also faced with food shortages due to declining salmon stocks (Ford et al. 2010; Ward et al. 2009), then the vessel noise that was a borderline concern at one point becomes an issue of critical conservation concern. When all of these stresses are looked at together, we call them cumulative or synergistic effects. We are becoming more and more of the ways that cumulative effects are what can cause a tipping point in the ability for an animal to function and survive. With that, it is becoming increasingly important for these cumulative effects to be considered in policy and management changes.
With an increased understanding of the ways that underwater noise effects the health of marine life comes the task of implementing regulatory policies and practices in order to minimize this impact. In 2012, the World Wildlife Fund held a workshop for wildlife managers and researchers to discuss management possibilities. Their final report and recommendations can be found here. In March 2014, Fisheries and Oceans Canada released their Draft Action Plan for the Northern and Southern Resident Killer Whales in Canada. This document suggested possible ways to address the concern of underwater noise for killer whales in British Columbia, including: “Consider area-specific boating regimes (speed restrictions, restricted whale watching hours) to reduce acoustic impact as well as risk of collision” (Fisheries and Oceans Canada 2014). However, Cetus and many other conservation organizations such as Raincoast Foundation, Wilderness Committee, Georgia Strait Alliance, the David Suzuki Foundation, and Ecojustice took contention with the Action Plan’s blatant lack of real action. Cetus’ statements can be found here, and the submission from Raincoast et al. is here.
The former Whale and Dolphin Conservation Society released this ad campaign to raise awareness and increase action on the effects of noise pollution on cetaceans and other marine mammals.
Thus, we are currently in the position of waiting to see what changes come of the Action Plan with respect to further regulating underwater noise in Canadian waters. Continuing to inform yourself on the effects of underwater noise is extremely helpful and crucial to the conservation of the species that are affected. Stay up to date on ways that you can support the creation of spacio-temporal restrictions on noisy activities or the creation of ‘noise-free zones’ in critical habitat areas. Please also consider donating to our work in order to ensure that we can help minimize the effect of underwater noise, particularly on cetaceans!
NOTE: while this post has focussed on the effect that underwater noise has on cetaceans, a great deal of research has demonstrated the detrimental effects that underwater noise has on other marine mammal species and fish as well.
Aguilar Soto, N., Johnson, M., Madsen, P.T., Tyack, P.L., Bocconcelli, A., and Fabrizio
Borsani, J. 2006. Does intense ship noise disrupt foraging in deep-diving Cuvier’s beaked whales (Ziphius cavirostris)? Marine Mammal Science 22: 690–699.
Bode, M., C.W. Clark, J. Cooke, L.B. Crowder, T. Deak, J.E. Green, L. Greig, J. Hildebrand, C. Kappel, K.J. Kroeker, L.L. Loseto, M. Mangel, J.J. Ramasco, R.R. Reeves, R. Suydam, and Weilgart, L. 2009. Statement to President Barack Obama of Participants of the Workshop on Assessing the Cumulative Impacts of Underwater Noise with Other Anthropogenic Stressors on Marine Mammals. Report of the Workshop on Assessing the Cumulative Impacts of Underwater Noise with Other Anthropogenic Stressors on Marine Mammals: From Ideas to Action. Monterey, California, USA, 26th-29th August, 2009, pp. 1-4.
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