Indonesia has a very high diversity of Cetacean, observation with good accuracy and precision must be a priority in every observation. Several methods have been developed to help calculate the marine mammal population, one of them by using Vertical Take-off and Landing (VTOL) Unmanned Aerial System (UAS). VTOL UAS is flown at a certain height to capture photos that contain the number of individuals in a pod, while also mapping the movements and recording their behaviors. The aim of this study was to determine the ideal angle to capture the photos. Several observation angles, 30°, 60°, and 90° were tested Observations were conducted in three sites in Indonesia (Sepa Island, Thousand Islands, Kepulauan Seribu National Park (TNKS); Liang Beach, Maluku Island; and Nai Island Kei Achipelago). The results showed that the angles greatly affected the number of objects in the photograph. For example, on the Island of Sepa, at the angle 30°, 60°, and 90°, the number of dolphins obtained were 3, 9 and 14, respectively. This study did not find any object rejection during observation with VTOL UAS. This study suggests that higher angle of photograph from VTOL UAS increases the accuracy of the observation of marine mammals.

Abstract. Diatin I, Effendi I, Taufik MA. 2020. The production function and profitability analysis of Gracilaria sp. seaweed polyculture with milkfish (Chanos chanos) and black tiger shrimp (Penaeus monodon). Biodiversitas 21: 4747-4754. Gracilaria seaweed is the main ingredient for making agar as a source of food and industry. Gracilaria culture in ponds with a polyculture system is one of the potential seaweed cultivation in Indonesia. This study was aimed to analyze the productivity, production input optimation, and profitability on the polyculture system of Gracilaria sp. with milkfish (Chanos chanos) and black tiger shrimp (Penaeus monodon). The survey method was used to notify the seaweed farmers from Indramayu, West Java, Indonesia. The study data were obtained from all seaweed polyculture farmers populations in the observational location by census containing two farmers groups, namely Gracilaria sp. with milkfish and black tiger shrimp (GMS symbol) and Gracilaria sp. with milkfish (GM symbol) polyculture system. This study resulted that GMS polyculture system obtained higher productivity than GM polyculture system. The GMS business scale was in the increasing return to scale condition, while GM was in the decreasing return to scale condition. The optimal condition of GMS polyculture system was performed by improving the black tiger shrimp seed input, milkfish seed, and milkfish feed, besides declining the working hours, while GM polyculture system was performed by decreasing the milkfish feed and farmers working hours. When the optimal condition is applied to the GMS polyculture system, then the business profit reaches five times, resulting in an increased profit margin of 112% with R/C becomes 134%. Meanwhile, GM polyculture system only reaches 65% business profit, 65% profit margin, and 25% R/C. The investment payback period from both polyculture systems became shorter. The application of production input efficiency on the GMS polyculture system is more prospective than GM polyculture system.