Acoustic Sanctuaries

Williams R., Erbe C., Ashe E., and Clark, W.C. 2015. Quiet(er) marine protected areas. Marine Pollution Bulletin 100: 154-161.

http://www.sciencedirect.com/science/article/pii/S0025326X1530028X

Killer whales (Orcinus orca) off the coast of B.C. (Photo Source: http://bcwhalewatchingtours.com/southern_residents.html)

Marine animals that use acoustic cues to hunt or find food, navigate, predator avoidance, and social interactions are particularly sensitive to noise pollution (2). Chronic background noise can interfere with these behaviors as well as cause negative physiological responses like stress or hearing loss (2). By preserving their habitat, acoustics included, these populations will have a better quality life.

Marine animals that are sensitive to sound may be particularly affected by the chronic noise caused by ships off the coast of British Columbia (1). Heavy water traffic from Vancouver and Seattle ports cause ‘hot spots’ of noisy areas where sound sensitive marine animals may be affected, and ‘quiet spots’ of refuge (2). To find sites of opportunity where noise is low and population is high, noise maps are compared with population maps while taking into account species specifics (figure 1). The purpose of Williams’ study is to identify and draw attention to the importance of preserving these quiet areas as a part of their habitat, and the beauty of it is that nothing has to change. By simply preserving these areas that aren’t used by ships and slightly modifying existing routes, there will be quiet areas for many marine animals.

Figure 1: “Example results using harbor porpoise data identifying high “risk” areas (high levels of animal density and anthropogenic noise) and high “opportunity” areas (high levels of animal density and low levels of anthropogenic noise). Map (A): Normalized harbor porpoise density (averaged over 4 surveys conducted June–Sept between 2004 and 2007) showing two regions of high density. Map (B): Cumulative, audiogram-weighted sound energy from ship traffic (June–Sept 2008), normalized to 0–1 and plotted only in geographic cells that had harbor porpoise density data. Map (C): the “risk” map, indicating the co-occurrence of cumulative ship noise and porpoises. Map (D): the “opportunity” map, indicating where porpoise density is high and ship noise is low.” (2) (Photo Source: http://www.sciencedirect.com/science/article/pii/S0025326X1530028X)

Williams et al. compared maps of the population density of 10 species in BC continental shelf waters and areas of high ship traffic. The 10 animals he looked at are: harbor seals, elephant seals, steller sea lions, Dall’s porpoise, harbor porpoise, fin whale, common minke, humpback whale, northern resident killer whales, Pacific white-sided dolphin, and sea otters (1). The Northern resident killer whales, fin whales, and humpback whales are all ‘at-risk’ species that are sensitive to the ship noise (1). Williams map overlay shows opportune areas to protect that are currently unused by ships but have high population densities. By preemptively creating acoustic sanctuaries you can avoid conflict with shipping companies catalyzing the conservation effort.

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Lit cited:

(1) Erbe C., Williams R., Sandilands D., and Ashe E. 2014. Identifying modeled ship noise hotspots for marine mammals of Canada’s pacific region. PLoS ONE. 9(11): e114362. doi: 10.1371/journal.pone.0114362 http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0089820

(2)Williams R., Erbe C., Ashe E., and Clark, W.C. 2015. Quiet(er) marine protected areas. Marine Pollution Bulletin. 100: 154-161. http://www.sciencedirect.com/science/article/pii/S0025326X1530028X