The Voice - 15 May 1996

Unique Probe Into Undersea Surveys

Researchers from Curtin University's Centre for Marine Science and Technology have embarked on an internationally significant three-year investigation of the environmental effects of underwater seismic surveys on marine life, including whales. Funded by the Australian Petroleum Production and Exploration Association (APPEA) and the Energy Research Development Corporation (ERDC), the study is in response to growing concerns from environmental groups and fishermen that the high sound levels used during undersea geophysical exploration may adversely affect marine animals.

Principal Researcher Rob McCauley said seismic surveys help petroleum companies identify geographical formations on the ocean bed, information which is vital to locating oil and gas reserves. "The use of high energy underwater sound sources or air gun discharges is central to their offshore exploration", he said. "The noise released from the underwater air guns penetrates the ocean floor, then bounces off different geographical formations as it reflects back up to the surface. The source tows long streamers of microphones which record the noise reflections and from this a picture of the sea floor can be built up. The noise can have a dramatic effect underwater. Imagine you're at home experiencing the sound of workmen drilling outside your window, creating an irritating, concentration-breaking noise from which you can't escape. Imagine then, being a marine creature, say a whale, going about your aquatic business, when from above a very loud, low frequency noise is let loose in your environs."

Underwater researcher Rob McCauley: unique investigation into the effects of undersea seismic survey explosions on marine life

The research will consider the effects on humpback whales, which frequent the coast of Western Australia.

The aim of the study is to provide a better understanding of the environmental implications and help companies design seismic surveys with minimal impact. In 1992 it was estimated that seismic surveys in Australian waters involved the firing of 2.8 to 3.6 million air gun discharges every three months, with much of this activity being in Western Australia's north west. In recent years there has been concern that such persistent high sound levels may interfere with the behavioural patterns of marine organisms, from invertebrates and fish, through to the bigger marine mammals like the humpback whale. Mr McCauley said a lot of seismic surveys take place off turtle nesting beaches in the north west and at this stage nothing is known about the effect this has on breeding patterns."

Over the next three years, the Curtin marine research team will conduct a series of experiments using sound models to predict how loud the noises are and measure the response of various marine creatures. "One part of our investigation will focus on the reactions of invertebrates, like lobsters, squid, molluscs and prawns, and a variety of fin fish within a controlled environment. We will measure the behavioural response to a single noise source," Mr McCauley said. "For the behavioural monitoring we will use underwater video equipment, acoustic transponders or sonar observations. All animals closest to the air gun will be monitored directly by underwater video."

The study will also involve a series of field experiments to measure the reactions of wild humpback whales, dugongs and sea turtles. "We will carry out controlled air gun approaches to these creatures within their natural environment. The noises will be stopped as soon as the whales or dugongs start to react or show avoidance. "The investigation will operate within a rigorous ethical framework, with approval from State and Commonwealth authorities," he said.