mcbem-2014-01-submission-wwf-en

At the operations stage, Northern Gateway has committed to reducing the underwater noise output of
Project-related vessels though the use of mandatory speed restrictions in the CCAA, “core humpback
whale area”, and “CCAA approaches”. Currently available information on the seasonal distribution of
humpback whales in the CCAA suggests that this species occurs in greater numbers in Wright Sound,
Squally Channel, Campania Sound and Caamaño Sound from May to November. For the purpose of the
assessment, these areas were referred to collectively as the core humpback whale area. The CCAA
approaches refer to areas within Hecate Strait, in close proximity to the CCAA (i.e., around Browning
Entrance and west of Caamaño Sound) within which additional seasonal speed restrictions may apply.
The spatial and temporal boundary of these two areas will be refined through data collected by six years
of marine mammal density surveys and a quantitative vessel strike analysis.
Vessel-based underwater sound typically increases with speed; the greater the vessel speed, the greater
the propeller cavitation noise. Consequently, Northern Gateway has set a maximum year-round speed
restriction for all Project-related tankers of 10 to 12 knots within the CCAA. While transiting the “core
humpback whale area” during 1 May to 1 November, tankers and tugs will travel at maximum speeds of
8 to 10 knots, unless otherwise required for safe navigation. In the “CCAA approaches”, Northern
Gateway will require tanker speeds to be less than 14 knots for the period 1 May to 1 November. Other
large vessels in the CCAA currently travel at speeds of 16 to 21 knots. Surveying of seasonal whale
densities and distributions will again be used to better define this period, and the quantitative vessel
strike analysis will be used to better define the geographical extent of these areas.
Acoustic modelling conducted for the Project predicted that reducing vessel speed from 15 knots (a
common speed for transiting tankers) down to 9.6 knots (as a result of Northern Gateway’s mitigations)
would reduce sound input into the environment by nearly 12 dB. To understand what a reduction by 12
dB means, decreasing sound levels by 10 dB reduces the distance that sound extends by a factor of
approximately three, and (at least in terms of human hearing) would be perceived as a sound that is half
as loud. Therefore, Northern Gateway’s commitment to reduce vessel speeds means that the zone of
influence for Project-related vessel noise in the CCAA is predicted to be 2-3 times smaller than in the
absence of mitigations, or in comparison to many of the large ships operating in the region now.
Finally, Northern Gateway has committed to a long-term marine research and monitoring program. This
program will include conducting a four-year passive acoustic monitoring study, and undertaking a
cooperative research initiative to address and adaptively manage important data gaps and identify
options for monitoring and reducing underwater sound levels throughout the CCAA. Northern Gateway
encourages a cooperative regional approach to developing mitigation measures for limiting the effects
of all vessels on marine mammals.
The potential effects of underwater noise associated with vessel traffic are not unique to Northern
Gateway; however, the approach that Northern Gateway is taking to minimize effects of routine
operations on marine mammals is unique in the shipping industry in British Columbia and many areas in
Canada and the United States. Northern Gateway believes that if other shippers and passenger liners in
British Columbia waters were to adopt similar types of measures, the marine environment would
actually see some net benefits in terms of reduced noise levels. Northern Gateway has committed to
minimizing their incremental contribution, and it is their hope that these mitigation measures will serve
as an industry example.
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