Mapping and characterisation of key biotic and physical attributes of the Torres Strait ecosystem (T2.1)

Task leader: Dr Roland Pitcher, CSIRO with Geoscience Australia, Queensland Department of Primary Industries & Fisheries, Queensland Museum.

This project is mapping ecosystems in central-eastern Torres Strait including:

• seabed habitat and biodiversity, distribution & abundance
• seagrasses
• water column attributes
• physical factors that drive the patterns in these ecosystems

The project will assess the status and condition of these ecosystems, and establish benchmarks to help managers assess the health of the ecosystem. In addition, the project will estimate the large scale effects of trawling on the seabed.

RV James Kirby, undertaking much of the surveying within the Torres Strait. Photo: CSIRO

The mapping has been done by using cost-effective methods such as towed-video, sediment grab, epibenthic sled, scientific trawl, water quality instruments and remote sensing (imagery, acoustics) -- optimized by stratified sampling.  The relationships between seabed biodiversity and the physical environment is being analysed and the ability to predict seabed assemblages will be assessed.

This information will be used for conservation planning, sustainable fisheries management, and monitoring -- ultimately helping to preserve the unique values of this region.

The information will be used by other researchers that want to understand ecosystem processes and dynamics an also for environmental risk/sustainability assessments in the management evaluations project.

A sponge garden found on the Torres Strait seabed. Photo: CSIRO

Objectives

Deliver baseline maps and other information needed to ensure that the Torres Strait Protection Zone (TSPZ) is sustainably managed. This information will also be used in plans being developed by AFMA and other regional, State and Commonwealth Government agencies to conserve biodiversity in half of the TSPZ that surrounds the trawl fishery.

Outcomes

• Improve knowledge about the status of ecosystems in the central-eastern Torres Strait, which is of use in Regional Marine Planning.
• Improve identification of marine species at risk.
• Estimate the level of exploitation of seabed communities in the area and the level of improvement/restoration required .
• Facilitate the development by stakeholders of sustainability indicators for bycatch species and seabed benthos which can be used in fisheries management to achieve environmental sustainability objectives under State and Commonwealth fishery and environmental legislation and delivery of agreed indicators for ESD reporting.
• Incorporate environmental indicators which can be measured into fishery management plans.
• Provide information which stakeholders can use to ensure: reasonable use of the area to maintain the ecosystem, bycatch & benthos and; develop and implement management plans to ensure an ecologically sustainable fishery.
• Make a strategic assessment of the TS trawl fishery which will meet AFMA Management goals, and State and Commonwealth fishery and environmental legislation.
• Integrate understanding of the central-eastern Torres Strait ecosystem into models that can evaluate alternative management strategies for the trawl fishery and contribute to sustainable development.

Summary of Progress

The underwater towed camera system. Photo: CSIRO

The design for sampling seabed habitats, fishes and invertebrates was completed in November/December 2003.

The first field trip was completed in January 2004 on the QDP-Fisheries vessel Gwendoline May. The field team visited 192 sites and successfully sampled 142 sites for seabed fishes and mobile invertebrates with a small scientific trawl net; 42 sites were too rough to sample. The samples have been transported to research laboratories and sorting is underway.

THe epibenthic sled used to collect samples of seabed plants and animals. Photo: CSIRO

The second field trip was completed during March-April 2005 on the JCU Research Vessel James Kirby. The field team visited 184 sites throughout the Torres Strait and sampled seabed habitats, animals and plants, including seagrass, with towed-video, digital still cameras, a small epibenthic sled and a sediment scoop. Sorting and identification of samples is now underway at research laboratories.

Preliminary maps of seabed habitats and assemblages have been produced from field station point data.

Further information

Phase 1 report to National Oceans Office (10MB pdf)

Maps

Seabed Substrate
Preliminary map summarizing the dominant seabed substrate types quantified by real-time video observations onboard the RV James Kirby during the Mar-Apr 2005 field trip.

Seabed Biological habitat
Preliminary map summarizing the dominant seabed biological habitat types quantified by real-time video observations onboard the RV James Kirby during the Mar-Apr 2005 field trip.

Seabed plant and animal assemblages
Preliminary map summarizing the amount of each type of seabed plants and animals sampled by the epibenthic sled onboard the RV James Kirby during the Mar-Apr 2005 field trip. Samples are being further sorted and identified in the laboratories of the partner agencies.

Seabed fishes and invertebrate assemblages
Preliminary map summarizing the relative amounts of fishes and other bycatch sampled by the scientific trawl onboard the FRV Gwendoline May during the Jan-Feb 2004 field trip. Samples are being further sorted and identified in the laboratories of the partner agencies.