This data set contains Simrad EK500 single beam echosounder data at 38 and 120 kHz and Simrad EA500 single beam echosounder data at 12 kHz from the Southern Surveyor. The EK500 data is primarily for water column characterisation (fish stocks, microplankton distribution) and on occasions for seabed classification (particularly prior to the EM300 swath mapper being installed), while the EA500 data is primarily for bathymetric readings.

This voyage provides an opportunity to test and refine optimal techniques to map and assess seabed habitat developed in a previous CMR project (NOO OP2000-SE02). Importantly, this voyage will use the National Facility's high-resolution EM300 swath mapper for its first program of biological and physical habitat mapping. The sampling locations are a number of submarine canyons and their immediately adjacent flanks on the west coast of Tasmania and east of Bass Strait. These are prime targets for our methods development because each canyon area is characterised by a great variety of seabed topography and benthic communities concentrated in a relatively small area (< 300 sq km). This voyage is also an opportunity to apply the data collected to marine resource management planning in the South East Region. Submarine canyons represent a type of habitat unit ("Level 3 biogeomorphic units") having a strong influence on the location of offshore Marine Protected Areas on the continental slope and rise, and many are likely to be biodiversity "hotspots". Several canyons are also the locations of the largest known aggregations of feeding and spawning fishes in the South-East Fishery region, and these support a range of intense, increasing and, in places, conflicting fishing activities. Given the immediate and increasing relevance of submarine canyons to conservation and fishery managers, it is then surprising to realize that virtually all those in the SE region remain unsampled by scientists, and are named only by commercial fishers. For these reasons, sampling on this voyage will focus on the "Big Horseshoe Canyon" mapped previously with the EM1002 and EM12 swath instruments (to enable comparison of data types, and to investigate temporal persistence of features), and several "new" areas. Sediment samples were taken for analysis by Geoscience Australia.

Multibeam echosounder data collected on Southern Surveyor voyage 04/2004 using the Simrad EM300 multibeam echosounder to acquire high resolution seafloor bathymetry and backscatter information. This voyage took place off the west coast of Tasmania and east of Bass Strait during April 2004. Ping rate varied according to depth. Data are stored in Simrad *.all raw format at CMAR and Geoscience Australia (GA). There are 972 files totalling 23 GB of raw data in this dataset. Additional information regarding this dataset is contained in the cruise report for this voyage and/or the data processing report (as available).

This voyage provides an opportunity to test and refine optimal techniques to map and assess seabed habitat developed in a previous CMR project (NOO OP2000-SE02). Importantly, this voyage will use the National Facility's high-resolution EM300 swath mapper for its first program of biological and physical habitat mapping. The sampling locations are a number of submarine canyons and their immediately adjacent flanks on the west coast of Tasmania and east of Bass Strait. These are prime targets for our methods development because each canyon area is characterised by a great variety of seabed topography and benthic communities concentrated in a relatively small area (< 300 sq km). This voyage is also an opportunity to apply the data collected to marine resource management planning in the South East Region. Submarine canyons represent a type of habitat unit (Level 3 biogeomorphic units) having a strong influence on the location of offshore Marine Protected Areas on the continental slope and rise, and many are likely to be biodiversity hotspots. Several canyons are also the locations of the largest known aggregations of feeding and spawning fishes in the South-East Fishery region, and these support a range of intense, increasing and, in places, conflicting fishing activities. Given the immediate and increasing relevance of submarine canyons to conservation and fishery managers, it is then surprising to realize that virtually all those in the SE region remain unsampled by scientists, and are named only by commercial fishers. For these reasons, sampling on this voyage will focus on the Big Horseshoe Canyon mapped previously with the EM1002 and EM12 swath instruments (to enable comparison of data types, and to investigate temporal persistence of features), and several new areas. Mark Lewis has videos recorded on voyage and photographs of deck shots & equipment used during the trip.

This is the CSIRO portion of the collaborative Tasmanian Aquaculture and Fisheries Institute, University of Tasmania (TAFI)/CSIRO Marine Research Project titled 'Understanding Shelf-break Habitat for Sustainable Management of Fisheries with Spatial Overlap', which aimed to map and understand shelf-break seabed habitats (~150-350m depths) around Tasmania, Australia, which is an area of interaction between two fishery sectors, giant crab trappers and finfish trawlers. Both of these have been expanding over the past decade, with potential of impact to target species abundance, habitat structure, and ecosystem structure. This project aimed to research the habitat effects of these activities over the period 2003-2005 through sampling of fished and unfished areas using video transects, multi-beam acoustic swath mapping, and collection of physical samples using sediment grabs and benthic sleds, using chartered vessels and a voyage of the National Facility FRV Southern Surveyor in 2004. Specific objectives for the giant crab (Pseudocarcinas gigas) habitat survey are as follows: - define and map giant crab habitat on the shelf edge, at several key locations off the Tasmanian east and west coasts; - detail distribution of giant crabs in relation to habitat features; - evaluate ecosystem links between habitats; - evaluate the vulnerability of habitat to damage by fishing (trawls and pots); and - evaluate the ability to obtain fishery independent information by video on the abundance, sex ratio, condition and size of giant crabs. The CSIRO portion of the work comprised a series of four surveys to assess the seabed habitats of the giant crab at the edge of the continental shelf around Tasmania. The image annotations collected for this project have been added to the Oracle data base BHIMAGE and the associated videos and still images have been archived as described in MarLIN record 14436 'Benthic Habitats Video Image Archive'.