Assessing Vessel Slowdown as a Mitigation Strategy for Reducing Acoustic Masking
The presence of sea ice has effectively preserved the western Canadian Arctic's natural underwater soundscape by making it inaccessible to most commercial shipping. Marine life there have therefore had little exposure to the anthropogenic (man-made) noise commonly reported at lower lattitudes. However, the presence of sea ice has been declining (a trend that is expected to continue) and thus the region is becoming more accessible for shipping - meaning increased interactions with marine mammals and fish are expected.
Increased shipping in the Arctic due to lower seasonal ice presence could lead to adverse noise effects on marine life near shipping lanes, in an environment that has historically been very quiet. As a result, a lot of work has/is being done to figure out a way that vessel traffic and noise can be managed in order to protect vulnerable marine life. Re-routing shipping corridors to avoid sensitive marine mammal habitat, regulating the number of vessels in certain areas at any one, and slowing vessels down so to lower the noise emissions and allow more time for whales to swim out of a ship's way (i.e. lower the collision risk), are three possible strategies to lower shipping impacts on marine mammals. In the Northwest Passage, there are areas where ships are unable to be re-routed or the shipping lanes be kept away from sensitive marine mammal habitat. For example, narrow passageways like the Prince of Wales Strait between Banks and Victoria Islands. In those areas, vessel slowdown could be the answer to reduce noise-related impacts on the whales and seals. In this research, we have been undertaking advanced acoustic modelling to investigate just how effective slowing vessels down might be at reducing acoustic masking in marine mammals. Since marine mammals depend on sound for critical life processes, acoustic masking can impair their ability to locate food, stay close together, communicate with one another and avoid predators or danger. Over the course of 10 months, we investigated how much relief in acoustic masking could be achieved if a container and cruise ship slowed down from 25 knots to 15 knots. See - Pine, M.K., Hannay, D.E., Insley, S.J., Halliday, W.D., Juanes, F. (2018). Assessing vessel slowdown for reducing auditory masking for marine mammals and fish of the western Canadian Arctic. Marine Pollution Bulletin 135: 290-302. |
Modelling vessel noise propagation in the Canadian Arctic
As well as researching the potential impact of masking effects from increased vessel activity in the NW Passage, we have been undertaking advanced propagation modelling of vessel noise through the Canadian Arctic. The two implementations being used are the commonly used parabolic equation method (specifically RAMGeo code) and Bellhop ray tracing. Both these methods are available at the Ocean Acoustics Library, or can be used in Curtin University's AcTUP platform.
For an example, see - Halliday, W.D., Insley, S.J., Hilliard, C., de Jong, T., Pine, M.K. (2017). Potential impacts of shipping noise on marine mammals in the western Canadian Arctic. Marine Pollution Bulletin 123: 73-82. |
Exploring the soundscape of the plainfin midshipman around Vancouver Island, British Columbia
During 2017 and 2018, we have been working with WCS Canada and the University of Victoria to characterise the calling behaviours and soundscape surrounding the plainfin midshipman fish around Vancouver Island. The aim of the research is to better understand the exposure rates and influence of vessel noise in their habitats during breeding.
see - Halliday, W.D., Pine, M.K., Bose, A.P.H., Balshine, S., Juanes, F. (2018) The plainfin midshipman’s soundscape at two sites around Vancouver Island, British Columbia. Marine Ecology Progress Series 603:189-200.
see - Halliday, W.D., Pine, M.K., Bose, A.P.H., Balshine, S., Juanes, F. (2018) The plainfin midshipman’s soundscape at two sites around Vancouver Island, British Columbia. Marine Ecology Progress Series 603:189-200.