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The changes in underwater sound levels as commercial vessels navigate through shipping lanes in the inland waters around the Gulf of Georgia and San Juan Islands were assessed. These in-situ measures build on previous, more experimental evaluations. Recordings from three acoustic moorings at Boundary Pass, Turn Point and Haro Strait, southern Vancouver Island, British Columbia, were used to compare sound field measures at vessels' closest point of approach before, during, and following a turn. Vessel types assessed included tankers, bulkers, vehicle carriers, containerships, and passenger vessels. A multi-variate linear regression confirmed the relationship between vessel speed and sound levels, showing that the course of the vessel was also influential. The slowest transit speeds, yet highest broadband (10 Hz to 100 kHz) and vessel noise levels were recorded as they manoeuvred at Turn Point. Vessel-derived sound emissions in the mid-to high-frequencies were also considerable. [ABSTRACT FROM AUTHOR]

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