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The authors of the comment first argue that ‘the definition of a ‘seismic period’ (Pinet et al. 2010) is not accurate enough and thus the relationship between seismic activity and calling behaviour is not clearly demonstrated nor is it supported’. The data and the evidence presented in our paper emphatically refute this argument. The definition of a ‘seismic period’ was defined to be very simple so as to eliminate the very reasons that the authors of the comment try to use to argue their case. On days and during times when seismic sparker pulses were present, as detected on data from all five seafloor recorders in the area where blue whales were closely observed and monitored, the rates of audible calling increased relative to periods when seismic sparker pulses were not present (Di Iorio & Clark 2010).
The authors of the comment present four items of contention.
We agree with the authors of the comment that ‘whale responses may vary depending on several parameters’, and that knowledge of the location of the operating vessel would allow a much more accurate analysis of such responses. Obviously, we would have integrated such data if they had been available, and we would still be interested in doing it for a more detailed analysis. Nevertheless, we believe that our analysis and results are straightforward and provide evidence that blue whales acoustically responded to the presence of seismic sparker operation by increasing their rates of calling.
Finally, the authors of the comment argue that the ‘sparker source is obsolete for modern hydrocarbon exploration’, which in this case is incorrect considering that one of the main objectives of the survey was also to locate areas of natural gas in the St Lawrence estuary (Bellefleur et al. 2006). Irrespective of the reason for the survey, it was conducted in the season and one of the areas with highest whale density, which Fisheries and Oceans Canada is considering for the establishment of a marine-protected area. Future seismic operations, also deploying low-medium power profilers, should therefore take into account the potential effects on whales and plan the surveys in a way to minimize the impacts on these animals and by considering the involvement of marine mammal observers.
The accompanying comment can be viewed at http://dx.doi.org/doi:10.1098/rsbl.2009.0885.