Dugong distribution, habitat and risks due to Fisheries and other anthropogenic activities in India

Abstract

The dugong (Dugong dugon), also called the sea cow, is one of the four surviving species in the order Sirenia, and it is the only existing species of herbivorous mammal that lives exclusively in the sea, including Indian waters. Conservation of the dugong, which is a flagship species, represents coastal conservation. This protected species occurs in the Gulf of Mannar, Palk Bay, Gulf of Kutch and Andaman and Nicobar Islands. The population of the dugong, which was once abundant, is assumed to have reduced to about 200 individuals in India. This number and the range of the dugong are believed to be continuously declining. Several reasons have been attributed to the decline in the dugong population, including sea grass habitat loss and degradation, gill netting, disease, water pollutants, indigenous use and poaching. This study was initiated to understand the dugong’s current distribution range and the magnitude of the anthropogenic threats faced by it and its habitat in India. The objectives include (1) determining the status and distribution of the dugong population in India, (2) understanding the risks faced by the dugong populations and their habitats, (3) assessing the status of artisanal fisheries in identified dugong habitats, (4) identifying the key areas where dugongs are present to conserve them and (5) understanding the attitude of fishermen towards conservation of dugongs. Three zones, namely the Gulf of Kutch, Andaman and Nicobar Islands and Gulf of Mannar–Palk Bay were identified as the study area on the basis of information published on dugong sightings, stranding records and seagrass presence. A standardised dugong catch/bycatch questionnaire developed by the CMS-UNEP Dugong MOU Panel was used for interview surveys after it was translated into regional languages. Region-specific threats to the dugong and its habitat were identified. Occupancy models were built in the program PRESENCE to identify critical dugong habitats using dugong sighting data from the past 5 years (2008 to 2012). The range of variables that influenced occupancy and detection were also assessed. Dugong occupancy was greatest in the Gulf of Mannar and Palk Bay, followed by the Andaman and Nicobar Islands, and lowest in the Gulf of Kutch. At present, the overall occupancy of the dugong in Indian waters is estimated to be 11% of the total surveyed area. Only 21% of the area sampled in Tamil Nadu was found to be occupied by dugongs. The corresponding proportion was 12% in the iii Andaman and Nicobar Islands and 1% in the Gulf of Kutch. Overall, the dugong distribution range has significantly decreased by about 85% in the distribution range of the dugong in India. Dugongs are also exist in regions outside the existing protected area (PA) network. Thus, conservation planning should also focus on dugong habitats outside PAs. Preventive measures, such as affording greater protection to dugongs and making fisheries sustainable with dugong friendly gear and craft, especially in the critical dugong habitats identified, are recommended. It is of the utmost importance to secure and strengthen community participation in the management of dugongs and their habitats in India. Model