Picture standing next to a 747 jumbo jet as it is taking-off, experiencing deafening roars that you can’t block out. Now imagine that you rely on your sense of hearing to locate family and friends, find food and navigate through the environment. Suddenly, that deafening roar is more than just headache-inducing: it fundamentally threatens your way of life and survival.

A blue whale (Balaenoptera musculus) swims underwater off the coast of Sri Lanka. 04/07/2009 © Greenpeace / Paul Hilton

Seismic surveys – which are used to locate sub-surface oil reservoirs - produce sounds that are much, much louder than a 747 and that can be heard across vast distances. In New Zealand, seismic surveying activities are widespread and set to become even more common as more of our waters are opened up for petroleum exploration. This will expose whales and dolphins to threats that we are only just beginning to understand.

The largest animal that has ever lived, the blue whale, was believed to be using New Zealand waters as a migratory highway only. However new research shows that our busiest oil and gas field is likely to be an important feeding ground for these endangered animals. In Canada, blue whales make social and feeding calls more often during seismic surveys – desperately trying to be heard above all the noise.

For whales and dolphins, filling up the ocean with so much noise is not just a nuisance – it can be down-right dangerous.  In the Canary Islands, Spanish naval sonar exercises have coincided with several mass strandings of beaked whales. Animals showed evidence of decompression sickness, almost certainly caused by sudden changes in their diving behaviour on hearing the sonar. Fatalities only ceased once a moratorium was placed on sonar use.  Sonar frequencies can overlap with seismic frequencies. Half the world’s species of beaked whale frequent our waters and so we cannot afford to overlook the impact that survey activities may have on these whales.

Never in their evolutionary history have whales and dolphins been exposed to such an auditory assault. Under new legislation seismic surveying is a permitted activity in New Zealand – no consent is needed and surveys can be carried out as long as some guidelines are followed. Yet there has been no published research on the effects of seismic activities on marine mammals in New Zealand. Without this knowledge, how can we possibly have any idea if current guidelines will do anything to protect our whales and dolphins?  Without clear evidence that our protective guidelines actually work, we should be taking a much, much more cautionary approach before allowing these activities in our waters.