ENVIRONMENTAL MANAGEMENT IN THE BASS STRAIT NORTHERN FIELDS 3D SEISMIC SURVEY

Abstract

The Northern Fields 3D seismic survey in Bass Strait was a large survey of 4,000 km2, carried out between the months of October 2001 to July 2002. The program attracted interest from various groups regarding the possible impacts of the survey on fisheries and cetaceans (whales and dolphins).

The survey was the first to operate in eastern Bass Strait after the Environment Australia Guidelines for Minimising Acoustic Disturbance to Whales, came into force, in September 2001.

The Northern Fields program was conducted in accordance with a method statement for the mitigation of impacts to cetaceans, developed by Esso to meet the requirements of Australian environmental legislation and acknowledge environmental best practice. The program utilised teams of three whale watchers who maintained a continuous rotational watch of two observers throughout the day. This proved to be a reliable element of the program and was one of several key learnings that may assist other companies in developing comprehensive and cost-effective mitigation strategies for future surveys.

Concerns raised by the fishing industry and some conservation groups about the potentially detrimental impact of seismic sources on commercial scallop larvae and fish populations were effectively addressed by avoiding commercial scallop areas during spawning periods. A controlled, in-situ study of scallops exposed to the acoustic source completed during the program conclusively demonstrated no significant variation in scallop mortality or muscle strength.

Observation data collected during this survey provided a sample of the cetacean population in Eastern Bass Strait during a large part of the annual migration cycle. These observations, which may be relevant to the planning and execution of future seismic surveys in the region, are discussed. The findings also provide valuable information for continued research into the distribution and conservation of whales and dolphins in Bass Strait.