Mapping Tasmania's seabed

Up until late 1999 the distribution of underwater habitats and detailed depth recordings in the Tasmanian seabed was unknown.

Then the SEAMAP Tasmania project surfaced, driven by the Tasmanian Aquaculture and Fisheries Institute and the Southern Natural Resource Management Regional Committee.

The aim was to map the seabed between Schouten Island and Bicheno and estuarine habitat in the Southern Tasmanian region.

Funding

Supported with over $200,000 from the Australian Government and contributions from the State Government, the project will improve our understanding of seabed habitats on the state's coast and coastal estuarine areas.

Activities

Project Manager Vanessa Lucieer said mapping was completed to the 40 metre depth contour but in shallower regions where 40 metres is a long way off from the shore, mapping was completed to 1.5 kilometres offshore.

"We began the mapping process by searching through aerial photo archives, but aerial photos are limited to eight to 10 metres in depth in Tasmanian waters," Vanessa said.

"We digitised the photos to get an idea of what the coastline looked like - rocky or sandy - and used an acoustic instrument called an Acoustic Ground Discrimination System (Single Beam Acoustics), which sends out a 'ping' of sound to the seafloor.

"The return of this sound generates an acoustic image, which we record and interpret back in the laboratory. Then we validate it with underwater video footage to confirm the signatures in the acoustics match up with what we've actually sampled.

"We've also conducted biological sampling of seagrass for density and to record the species, as well as core and sediment sampling to see if there are macro-invertebrates or what the shell composition is in the substrate."

Achievements

Vanessa and her colleague Miles Lawler spent up to 25 weeks per year over the past five years working on a research vessel collecting this seabed data. The team has almost completed the southern seabed from Whale Head to Hellfire Bluff. The north west region from the Tamar River to Hunter Island is being mapped this year.

"This is groundbreaking stuff in terms of improving fisheries management," Vanessa said.

"The estimate of reef areas has revolutionised research in the marine environment and expanded on scientific knowledge to set catch limits and improve estimates of population modeling for wild fish species."

More information

• The series of seabed habitat maps for Tasmanian State waters can be downloaded from www.utas.edu.au/tafi/seamap/.

Australian Government NRM Team
GPO Box 787
Canberra ACT 2601 Australia
1800 552 008 (toll-free)

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