Indonesian Manta Ray Habitat Use disturbance to this threatened species by tourism, regulations for the number of boats and interactions, especially during key reproductive times should be considered. Further, strict fishing regulation in the area is recommended as fishing gear entanglement was identified as a threat to this population.

International concern is growing with regard to the sustainability of manta and devil ray (collectively mobulids) fisheries as demand for mobulid products has increased in international markets over the last decade. While Indonesia has been reported to be one of the worlds’ top three catchers of mobulid rays, detailed information on these fisheries and the status of Indonesian mobulid populations are lacking. Through collection of historical and recent mobuild fisheries data from published and unpublished sources, this study aimed to identify trends in abundance of Indonesian manta and devil rays and explore socio-economic factors and incentives associated with mobulid fisheries. Comparison of catches from 2001-5 to the most recent data from 2013-14 revealed dramatic declines in mobulid landings over the study period of 64% at Cilacap, 75% at Lamakera, and 94% at Tanjung Luar. The largest declines were observed for Manta spp. and the two large devil rays, Mobula tarapacana and Mobula japanica. Anecdotal reports indicated that catches had declined substantially at three additional sites and local extirpations are strongly suspected to have occurred at three locations. A lack of data on the population ecology of Indonesia’s mobulids makes it difficult to determine whether natural fluctuations may be playing a part in the declining catch rates. However, mobulid life history traits, including low reproductive rates and late age of sexual maturation, indicate that fishing pressure is likely the primary driver in these declines. Interviews in Lamakera, a community which depends on income from its targeted mobulid fishery, suggest that programs focused on education, training and infrastructure development to enable shifts to sustainable livelihood alternatives are likely to offer the most successful path to long-term conservation and management of manta and devil rays, while simultaneously yielding economic and social benefits to fishing communities.

Indonesia has a very diverse shark and ray fauna and is the largest chondrichthyan fisheries in the world. Most Cilacap (32 species), and at Pelabuhan Ratu (27 species). A total of 55 species of rays belonging to one oi 12 families were recordeci from the same landing sites^ The most speciose and commonly recorded family of rays was the Dasyatidae, which was represented by 28 species, and contributed 65.2% to the total number of chondrichthyan individuals recorded. The most abundant dasyatids recorded were the smaller ray species Neotrygon kuhlii, Dasyatis zugei, and Himantura walga' and the larger species Himantura gerrardi and Himantura fal which collectiveiy comprised 57 8% of the total number of all chondrichthyans ianded.

Studies on artisanal shark fisheries in Tanjungluar - East Lombok were conducted during the year 2001-2011 (except in 2003 and 2007). A sampling method called “rapid market survey” method was employed to collect catch data from surface and bottom longlines fishing, rapidly. Biological data and fisheries data were collected during survey. Catch data for shark were also obtained from daily records filled by TPI officers in Tanjungluar between 2009 and 2010. The results showed that shark<br />longline fishing was conducted every month. The trend of shark catches relates to the number of fishing vessels, fishing ground, and weather conditions at sea. The period between July and September is a transitional season from East to West seasons. During this season, the wind strength is weakened and a good fishing season for the fishers. The lowest catch occurs in January (1.06 tonnes) and the highest catch in September with the total catch of 24.6 tonnes. Sharks caught by surface longline were dominated by Silky shark, Carcharhinus falciformis (40-90%) with the size range of 100-125 cm. The catch of bottom longline was mostly consisting of fish in mature condition that dominated by Grey reef shark (<em>Carcharhinus amblyrhynchos</em>), Common black tip shark (<em>C. limbatus</em>), Spot tail shark (<em>C. sorrah</em>), and Scalloped hammerhead shark (<em>Sphyrna lewini</em>), with the size range of 125-200 cm, 170- 250 cm, 100-150 cm, and 170-300 cm, respectively. Surface longline fishing occurs in the offshore waters in depth more than 200 m to 3000 m, whereas bottom longline fishing is operated at a depth of 50-100 m around islands.

This paper reviews the biodiversity and habitat preferences of living sharks in the Southeast Asian region accumulated from published literatures including journals, books, proceedings, unpublished technical papers, and technical reports as well as authors’ knowledge and experiences working in this field. A total of 196 species of sharks from nine orders and 30 families have been recorded inhabiting from fresh water to deep ocean in this region. Indonesia recorded the highest diversity with 114 species from 27 families followed by the Philippines with 96 species (27 families), Thailand 76 species (21 families), Vietnam 70 species (23 families), Malaysia 68 species (19 families), Myanmar 64 species (19 families), Brunei Darussalam 45 species (15 families), and Cambodia with 26 species from 10 families. Many species still need to be confirmed and are most probably new species. In term of habitat preferences, 83 species of sharks (42.3%) inhabit continental/insular shelves (SHL) followed by continental/insular slopes (SLO) with 48 species (24.5%), shelf to slope (SHS) with 26 species (13.3%), and shelf to oceanic (SHO) with 16 species (8.2%). Only nine species (4.6%) inhabit oceanic and six species (4%) obligate freshwater and euryhaline freshwater/shelves.