Assessment of Vessel Noise within the Southern Resident Killer Whale Interim Sanctuary Zones

Abstract

The Government of Canada, aiming to reduce SRKW exposure to underwater noise from vessels, implemented Interim Sanctuary Zones around Saturna and Pender Islands (Salish Sea) from 1 June to 31 October 2019. JASCO Applied Sciences (JASCO) performed a study to quantify vessel noise both with and without the implementation of these zones to estimate their effectiveness in reducing vessel noise levels within the zones. JASCO’s cumulative noise model was applied for each zone to predict monthly averaged noise levels associated with vessel traffic conditions before and during the implementation of the sanctuary zones. The effectiveness of these zones is assessed quantitatively according to the estimated changes in noise levels. The results, which consider multiple commercial, government and recreational vessel classes, show that this mitigation approach would result in a decrease of unweighted noise levels by, on average, 0.5 (±0.4) dB within the Saturna Island Interim Sanctuary Zone and 3.0 (±1.0) dB within the Pender Island Interim Sanctuary Zone. The decrease is greater for audiogram-weighted noise levels: 2.2 (±1.1) dB and 4.6 (±1.3) dB, respectively. These results are based on an idealized level of compliance by vessels in the area, and accounts for the exemptions stated in the 2019 Interim Order.