Behavior and Distribution of Cook Inlet Beluga Whales Before and During Pile Driving Activity

Five stocks of beluga whales (Delphinapterus leucas) exist in U.S. waters. Cook Inlet beluga whales are genetically distinct and geographically isolated from the other stocks. They are listed as endangered under the U.S. Endangered Species Act. Many factors are identified as potential threats to Cook Inlet beluga whales, including coastal zone development and anthropogenic noise. The Port of Anchorage Marine Terminal Redevelopment (MTR) Project in Anchorage, Alaska, involves several types of in-water construction including dredging, gravel fill, and pile driving. Pile driving is a major concern because of potential harassment from in-water noise produced by this activity. We investigated beluga whale behavior before (2005–2006) and during (2008–2009) pile driving activity at the MTR Project. Shore-based visual observations were conducted to document beluga behavior in the presence and absence of pile driving activities. A Pearson’s correlation coefficient (2-tailed) was used to examine the relationship between monthly sighting and pile driving rates. There was no significant correlation between monthly sighting and pile driving rates; nor was there a significant difference in sighting rates or mean group size. Mean sighting duration was shorter during pile driving (18 ± 3 min versus 39 ± 6 min). There was also an increase in traveling through the study area relative to other behaviors during pile driving, and an increase in diving with reduced observed feeding. There were significant changes in group composition and increased group dispersion during pile driving. These results suggest that pile driving has potential negative impacts on beluga whales, but whether the impact is long- or short-term is unknown.

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Lindsey Saxon Kendall and Leslie A. Cornick. Published in Marine Fisheries Review 77(2), 2015. dx.doi.org/10.7755/MFR.77.2.6