My masters research quantified underwater sound levels at four industrial sites in the Bay of Fundy, and related these noise levels to harbour porpoise presence.
Underwater noise was recorded for 3 minutes every 30 min for ~ one week each month, 2011-2012. These recordings were analyzed for ambient, average, and maximal sound levels (dB re 1uPa). The sound levels were also adjusted to account for the sensitivity of the harbour porpoise audibility system.
Harbour porpoise presence was quantified using Porpoise Detectors (PODs; Chelonia UK). These were set concurrently with hydrophone systems recording noise.
Noise levels were found to be low-to-moderate, depending on site and season. Overall, the low frequency, continuous noise produced from shipping did not appear to affect harbour porpoise presence, although evidence for short-term displacement was seen.
Ocean noise effects on marine mammals are of widening concern, especially with the endangered North Atlantic right whale in the Bay of Fundy. Large baleen whales are more sensitive to low-frequency sounds than the high-frequency communicating harbour porpoises. Increasing vessel traffic in the Bay of Fundy and around the world could be detrimental to many marine mammal populations.