The South East Australian Marine Ecosystem Survey: untangling the effects of climate change and fisheries

Project number: 2022-091
Project Status:
Current
Budget expenditure: $300,000.00
Principal Investigator: Richard Little
Organisation: CSIRO Oceans and Atmosphere Hobart
Project start/end date: 30 Jun 2023 - 30 Dec 2025
Contact:
FRDC

Need

The marine waters of Southeast (SE) Australia are one of a series of global ocean-warming hotspots. In this region, the East Australian Current is extending pole-wards, resulting in warming of ocean surface at a rate four times the global average. Many species have extended their distributions southward, with potential changes in local abundance. In addition, climatic extreme events, such as marine heatwaves, are leading to additional impacts in the region. Projections show that these changes, and the associated biological responses, are expected to continue in the next century.

In this hotspot lie important fisheries, providing the bulk of fresh fish to Melbourne and Sydney markets. The Southern and Eastern Scalefish and Shark Fishery (SESSF) has a total catch of about 20,000t and a value above $80 million. Concerns about the ecological, economic and social sustainability of this fishery raised in the public, and by scientists, over the years, have prompted a series of management responses, initiatives and regulations. In the hotspot also lies an Australian Marine Reserve network established to protect and maintain marine biodiversity and ensure the long-term ecological viability of Australia's marine ecosystems.

Observations from the Australian commercial fisheries regulator, the Australian Fisheries Management Authority (AFMA) suggests that the abundance of some species have declined, while others have increased. Additionally, some species that have been historically over-fished do not seem to be recovering despite reduced fishing pressure. The South East Australian Marine Ecosystem Survey will seek to answer the questions:

1. Despite reduced fishing pressure, have fish abundances in the SESSF really declined in 25 years? And if so, why?

2. Are species shifting their ranges to places outside of where they have been historically found, including to the continental slope?

3. What are the prospects for the future?

Comprehensive bio-physical and ecosystem assessments of the shelf were last conducted 25 years ago. This project will repeat the surveys to document changes, and will establish a new baseline for the continental slope. Specifically, it will help answer the broad questions:

1. How and why have fish assemblages and species abundances changed in the southeast ecosystem, and can the causes be mitigated?

2. How does this affect the multiple-use management of the region for fisheries, conservation and biodiversity and the hive of activity from oil & gas, and renewable energy sectors?

Objectives

1. To determine changes in the assemblage structure (composition, abundances, distributions) of continental shelf and slope fishes (including a focus on a suite of commercially important species such as redfish, jackass morwong, pink ling, tiger flathead, eastern school whiting and ocean perch) by comparing new survey data to historical baseline data.
2. Expand our understanding to new areas on the continental shelf, to fill gaps in our understanding and knowledge
and on the continental slope to establish a new baseline for future surveys
3. Provide guidance for adaptation of industry and management to the future of the fishery in terms of emerging commercial species, non-recovering species, and a baseline sample for recently announced SESSF closures.
4. Provide training opportunities to Early and Mid-Career Researchers in fisheries and marine research

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Developing biomass assessment approaches, harvest methodologies and biosecurity knowledge for wild-harvest of seaweeds in southern Australia

Project number: 2021-112
Project Status:
Current
Budget expenditure: $576,519.00
Principal Investigator: Jason E. Tanner
Organisation: University of Adelaide
Project start/end date: 30 Mar 2023 - 29 Jan 2026
Contact:
FRDC

Need

After many years of interest but little on ground activity apart from a few established operations based on the harvest of beach-cast material, the seaweed industry is starting to gain momentum in southern Australia. There is particular interest in the farming of Asparagopsis for its methane reducing properties in ruminants, but also in several species for human consumption and other uses, including the golden kelp Ecklonia radiata. While much of the focus is on the development of an aquaculture industry, this needs to be supported by the wild harvest of seedstock, at least in the early years, and there is also some interest in wild-harvest for product. However, the knowledge base and tools available for managers to regulate this emerging industry are limited. This proposal aims to start filling in some of these gaps. The first is to develop an understanding of the biomass present in targeted areas, and importantly, the development of a rapid assessment tool to do this, which can then be used to form the basis of a stock assessment methodology as the industry expands. The second is to develop harvest methodologies that allow for the recovery of local stocks, and which can be used to inform rotational harvest strategies by documenting how long recovery takes. The third is to develop an understanding of some of the biosecurity issues likely to be faced by industry and regulators, which will allow managers to make informed decisions around translocation policies to both prevent the spread of disease, and to maintain the genetic integrity of natural populations.

Objectives

1. Develop a rapid assessment tool for species specific subtidal macroalgal biomass, initially for Asparagopsis armata, A. taxiformis and E. radiata.
2. Develop harvesting methods for the above species that ensure that local populations are not depleted, and that ecosystem function is not compromised.
3. Review literature on macroalgae diseases, pests, health management strategies and population structure.
4. Identify information and approaches to define health management units.
5. Collate information and build an initial basic approach to translocation.