Controlled source level measurements of whale watch boats and other small vessels

Abstract

The Vancouver Fraser Port Authority’s Enhancing Cetacean Habitat and Observation (ECHO) program sponsored deployment of two autonomous marine acoustic recorders (AMAR) in Haro Strait (BC), from July to October 2017, to measure sound levels produced by commercial vessels transiting the strait. Fisheries and Oceans Canada (DFO), a partner in ECHO, supported an additional study using these same recorders to systematically measure underwater noise emissions (0.01-64 kHz) of whale watch boats and other small vessels that operate near Southern Resident Killer Whale (SRKW) summer feeding habitat. During this period, 20 different small vessels were measured operating at a range of speeds (nominally 5 knots, 9 knots, and cruising speed). The measured vessels were categorized into six different types based primarily on hull shape: ridged-hull inflatable boats (RHIBs), monohulls, catamarans, sail boats, landing craft, and one small boat (9.9 horsepower outboard). Acoustic data were analyzed using JASCO's PortListen® software system, which automatically calculates source levels from calibrated hydrophone data and vessel position logs, according to the ANSI S12.64-2009 standard for ship noise measurements. We found clear positive correlations of source levels with speed for all of these vessels; however, the speed trends were not as strong as those of large commercial vessels.