Use of the Bight by Southern Bluefin Tuna and Potential Impacts of Noise Associated with Oil and Gas Exploration

USE OF THE BIGHT BY SOUTHERN BLUEFIN TUNA AND POTENTIAL IMPACTS OF NOISE ASSOCIATED WITH OIL AND GAS EXPLORATION

At a glance Overview derived from aerial surveys of young southern bluefin tuna in the Bight) contribute to the Project title Southern Bluefin Tuna are an important apex assessments. Southern bluefin tuna: predator in the Great Australian Bight ecosystem. spatial dynamics and The Bight provides a summer home for young The Challenge potential impacts of noise southern bluefin tuna (one to four years), with associated with oil and gas Little is known about the response of southern large numbers migrating into the warm, shelf exploration bluefin tuna, or fish in general, to noise generated waters each year to feed on abundant prey by human activities. This means that the potential (predominantly sardines). impact on southern bluefin tuna, occupying those Project summary shelf and shelf slope areas of the Bight earmarked To better understand While in the Bight, southern bluefin tuna are as the focus of oil and gas exploration, are unclear. the feeding, diving and targeted by the Australian purse seine fishery migratory behaviour which captures young fish to fatten for the If southern bluefin tuna are impacted by noise and habitats of juvenile export market. The fishery was valued at $153.5 from activities associated with oil and gas southern bluefin tuna in the million in 2012–13. operation, this could affect the annual aerial Great Australian Bight, in surveys that contribute abundance estimates to As the young southern bluefin tuna move into the context of oil and gas support southern bluefin tuna management and in the Indian Ocean and Tasman Sea at the end of exploration and extraction. turn impact on fishing operations in the Bight. summer, they are targeted by recreational fisheries Project investigators in South Australia, Victoria, Tasmania, New South This project will investigate potential changes in CSIRO Wales and Western Australia, and international the movement and behaviour of southern bluefin longline fleets in the Pacific, Indian and Southern tuna in the Bight that may be associated with Program partners Oceans. increased noise. CSIRO, BP, SARDI, the Southern bluefin tuna belong to one population It will analyse data held by CSIRO on the University of Adelaide that spawns only in the north-east Indian Ocean movement, migration and behaviour of southern and Flinders University in the vicinity of the Java Sea. Commercial bluefin tuna collected across the period are working on a $20 fisheries are managed internationally under the 1994−2009 (before exploration activities), and million research program Convention for the Conservation of Southern data from archival tags deployed during the period to better understand the Bluefin Tuna, which is administered by the of exploration (2013−2016). environmental, economic Commission for the Conservation of Southern and social value of the Bluefin Tuna (CCSBT). If changes in the movement and behaviour of Great Australian Bight. southern bluefin tuna are detected, they will be The CCSBT oversees regular assessments examined for potential flow-on impacts on fishery Project contacts of southern bluefin tuna and sets national monitoring, assessment and management. The Dr Campbell Davies catch allocations according to a management quantification of any behavioural changes will CSIRO procedure designed to rebuild the stock from guide the development of potential measures E: [email protected] previously over-fished levels. Fishery-dependent required for mitigating such impacts. data (commercial catches) and fishery- independent data (estimates of abundance The Research understanding the variability in the feeding, diving and migratory behaviour CSIRO will develop novel statistical and habitats of juvenile southern bluefin methods for estimating positions, tuna in the Great Australian Bight. It behaviours and changes to feeding will examine the environmental drivers patterns in individual southern bluefin tuna associated with these behaviours using from electronic tag data. data collected across a period of three Models of juvenile southern bluefin tuna decades. This will provide important dynamics in the Bight will be used to information for the identification and highlight patterns of change across three development of mitigation measures that decades, including the period before and may need to be implemented to reduce impacts, resulting in long-term benefits during current oil and gas exploration. Above: A Juvenile southern bluefin tuna tagged with a for the fishing and aquaculture industry, small yellow conventional tag ready to be released back The research will involve: the Bight ecosystem, and the broader into the water. Australian community. • deploying electronic tags to collect feed and behave. She has tagged tunas, data on juvenile southern bluefin The People billfish, sharks, seabirds, seals and whales tuna over the short (less than one from the tropics to Antarctica. year) and long (one to four years) Dr Campbell Davies of CSIRO has a Dr Toby Patterson of CSIRO examines term; background in applied marine science, in the use of animal movement and particular the spatial ecology of fish and behaviour data for conservation and • improving statistical methods for fisheries, marine conservation planning, fisheries management. He specialises in estimating the movements of fish and the development and evaluation of statistical analysis of electronic tag data from tag data (geolocation); adaptive management systems. and has studied tracking and behaviour • developing new methods for Dr Karen Evans of CSIRO develops and data from tuna, sharks, whales, seabirds, investigating variability in diving deploys tags, and analyses their data turtles, seals and reindeer. behaviour and environmental to see how top order predators move, influences on this behaviour;

• analysing feeding behaviour in relation to prey availability and environmental conditions;

• developing habitat models based on both tag and aerial survey data to show where southern bluefin tuna and human activities such as development and exploration are likely to overlap; and

• reviewing historical exploratory activity and other noise generating activities (such as commercial shipping) to provide a historical noise

profile for the region. Above: Schematic of 2-5 year old southern bluefin tuna migrations, showing the distance and patterns of movements. Movements between the Great Australian Bight and the Pacific Ocean (dashed purple) are less well known than those between the Great Australian Bight and the Indian Ocean. It is also not clear if some southern The Impact bluefin tuna spend their summers in an area south-east of South Africa and an area south of Western Australia (hashed orange). This project will provide a basis to distinguish any potential impacts of oil and gas exploration, and other human activities in the region, by better

For more information Dr Steven Lapidge Great Australian Bight Research Director [email protected] www.misa.net.au/GAB