Great Barrier Reef dugong distribution and relative density - Spatial model of aerial surveys from 1986 - 2005 (MTSRF, JCU)

This dataset shows a spatial model of the distribution and relative density of dugongs (Dugong dugong) in the Torres Strait region based on an aggregate of 19 years (1986, 1987, 1992, 1994, 1999, and 2005) of systematic aerial surveys. For more information on the methods used in the creation of this dataset see Grech. A., and Marsh. H. (2007) - Prioritising areas for dugong conservation in a marine protected area using a spatially explicit population model, Applied GIS, 3(2), 1-14.

All surveys were conducted in late spring or early summer when weather and sea states provide optimum survey conditions.

This data presents the results of a model of dugong distribution and abundance, based on data collected from dugong aerial surveys, in conjunction with geostatistical techniques including universal kriging (Grech and Marsh 2007). After completing the model, frequency analyses were conducted to categorise relative dugong density and distribution to identify areas of low, medium or high conservation value.

The modelled abundance and distribution show the relative density of dugongs (areas where there are more or less dugongs) and NOT the absolute dugong density as corrections for perception bias (animals that are available to, but missed by, observers) and availability bias (animals that are unavailable to observers because of water turbidity) can only be applied at the spatial scale of entire surveys (thousands of square kilometres), making them inappropriate for the spatial scale for this dataset. Nonetheless, the relative densities among regions should be approximately comparable (H. Marsh, personal communication).

This dataset is being updated as part of Project 1.2 of the National Environmental Research Program.

This dataset is an estimate of relative dugong density (number / km^2) and the conservation value with a 3-point rating (high, medium, low).

Note: More recent surveys were completed under the NERP program.