Assessing the effects of changes in Great Barrier Reef Marine Park Zoning plans on southern mid-shelf shoals using towed video (Towvid) (MTSRF Project 4.8.2)

Brief description

Towed video (Towvid) surveys were undertaken in February/March 2007 and August/September 2007 on two pairs of discrete deepwater shoals in the mid-shelf section of the southern Great Barrier Reef. Within each pair, one shoal was from a 'green zone' (closed to all fishing) and the other from a 'blue zone' (open to fishing), based on the rezoning of the Great Barrier Reef Marine Park, carried out in 2004. The pairs of reefs chosen were: East Warregos (green) and West Warregos (blue); Barcoo Bank (green) and Karamea Bank (blue). A lightweight towed video system developed by AIMS was used to survey seabed habitats on and around the four shoal sites. The camera was deployed and towed from the stern of RV Cape Ferguson while maintaining a speed of approximately two to three knots. During camera deployment an observer used custom software developed for use with the towed video system to conduct a real-time seabed classification based on biotic and abiotic habitat components. The classification data was logged simultaneously with GPS position, depth sounder data and time. The resultant habitat observations were thus geo-referenced for later spatial analysis. Towed video surveys were undertaken to characterise the habitat on features identified from the digital terrain models produced from multibeam acoustic mapping, as likely productive fish habitat. This information was then used to determine placement of BRUVS (TM). This is one component of a series of surveys conducted as part of this MTSRF project, see also separate metadata records on:Reef base shoals (Capricorn-Bunker, Pompey and Swains Groups) Shoals off Cardwell Shoals off Cairns Magnetic Shoals (Townsville)

Lineage

Maintenance and Update Frequency: asNeeded

Statement: Statement: Because of the spatial extent of the shoals, systematic survey of the entire shoals was not possible. The towed video survey did not attempt to quantify the spatial extent of the various habitats on the shoals, but was used only to identify areas of suitable habitat for the deployment of BRUVS (TM). These were identified as the areas at the base of the shoal where hard substratum was outcropping and areas on top of the shoal with rugged topography that were likely to be productive fish habitats.

Notes

Credit
Speare, Peter J, Mr (Principal Investigator)