Population Estimate and Foraging Niche of Dugong (Dugong dugon) in Davao Gulf

Abstract

This study focused on the seagrass habitat quality assessment and population estimate of dugong in Davao Gulf. It was carried out through interview/survey and a three-month dugong daily monitoring from an elevated facility set along the shoreline. Line transect quadrant method (LTQM) and SCUBA diving were employed to assess the seagrass beds in the study sites. Not less than 14 dugongs were counted in New Argao (12) and Talicud (2), mostly between 8AM-12NN and 1PM-4PM. Simultaneous occurrence of dugong in New Argao and Talicud was observed between November- December 2008. Of the 14 seagrass species found in Davao Gulf, the Halophila species was the most preferred food of dugong with a herbivory rate of 80%. Approximately, 1, 705 sq. m were occupied by feeding trenches within the three-hectare seagrass bed having a potential biomass production (wet weight) of 164.32 grams/sq. m. A dugong consumes 18.68 kg (wet weight) of seagrass per day. Thus, the seagrass beds in New Argao can sufficiently sustain the food requirement of dugong in the area. Protecting the foraging niche of dugong is significant to address the declining population of dugong and to increase the chances of seeing them in the wild.