NAILSMA 2013 'Developing boat-based survey methods for dugong and marine turtles: Field trials at Montgomery Reef, Western Australia, August 2012'

Dugong and marine turtles are species of conservation and cultural significance to Indigenous and non-­‐Indigenous Australians. Tropical north Australia supports the largest and healthiest populations of these species, but data on size and trends in population and abundance are sparse for many areas. Accordingly, monitoring and mapping dugong and marine turtle distribution and abundance are priorities in national and regional species management, as well as in community-­‐based management plans developed by Indigenous sea country managers. Established methods to survey dugong and marine turtles include aerial surveys for dugongs and beach-­‐based nesting counts or tagging studies for turtles. In the context of north Australia, these methods have limitations with regard to cost and feasibility; the level of community engagement in field studies; as well as community access, ownership and understanding of study results. In the case of marine turtles, some three decades of nesting census data are required to discern long-­‐term trends against high annual variability in nesting numbers. An expensive, logistically challenging, decades-­‐long commitment to a marine turtle tagging and nesting beach study is beyond the resources and capacity of most community-­‐based organisations in north Australia. Accordingly the North Australian Indigenous Land and Sea Management Alliance Limited  (NAILSMA)’s I-­‐Tracker program is working with Indigenous land and sea managers and scientists to develop tools that utilise and build on local Indigenous ranger capacity to monitor marine turtles and dugong. These tools include recording in-­‐water observations, counts of nests and nesting turtles and stranded or entangled animals using the I-­‐Tracker Saltwater Country Patrol application (see http://www.nailsma.org.a /i-­‐tracker/saltwater-­‐country-­‐patrol-­‐application). The toolbox also includes a dedicated boat-­‐based I-­‐Tracker application that uses line transect methods to estimate distribution and abundance of local populations. This report presents results of a field trial conducted at Montgomery Reef, Western Australia in August 2012 of the dedicated boat- ‐based I-­‐Tracker Turtle and Dugong Survey application. The project is a collaboration between the Dambimangari Rangers, the Kimberley Land Council (KLC), NAILSMA and CSIRO. The survey method and I-­‐Tracker application used were based on previous research and field trials conducted by NAILSMA, CSIRO, and the Wunumbal Gaambera Aboriginal Corporation and its Uunguu Rangers with funding from the National Environmental Research Program. A total of 2,363 turtles and five dugong were recorded over four days at Montgomery Reef including 2,289 Green turtles and 18 Hawksbill turtles. The majority of turtles were observed at the reef edge on an incoming tide. Traditional Owners and hunters report that turtles move onto the reef flat with the rising tide to feed. On average 133 Green turtles were sighted per hour of effort on  transect across both boats used. Whenever possible, for each turtle sighting, species, size,  location and distance from the boat,and behaviour were recorded; however, in some areas turtle density was so high it was not possible to record all variables for each turtle. To accommodate this, a ‘Green turtle counter’ option was included in the I-­‐Tracker application to record very  high density groups of turtles. This counter was modified during the field trial so that even in these very high density areas, both distance from the boat and size class were captured, while side of the boat and behaviour were dropped. High rates of tidal flow (tidal ranges 8-­‐9m) and water turbidity (and hence low sightability of animals) meant that survey transects were limited to shallow waters adjacent to or on the reef. Survey participants demonstrated a high level of uptake of and competency with the survey method and in using the field personal digital assistants (PDAs) and computer to enter, upload and review survey data. The results of post-­‐survey interviews with individual Dambimangari Rangers and Traditional Owners show a high level of satisfaction in the applicability and relevance of the method to Indigenous sea country management.