Adriani Sunuddin

Formulating marine sanctuary designation for sustainable management of blue swimming crab in Lancang Island, Kepulauan Seribu

Lancang Island is the center of fisheries of blue swimming crab in Kepulauan Seribu, Jakarta. Most of the inhabitants in this island are fishermen, and blue swimming crab is the main target without considering the stocks. One of the management effort of blue swimming crab by the government is the restriction of catchment size. To support the government policy and to maintain the population stocks and the sustainability of blue swimming crab around Lancang Island, we need another effort such us proposing area of Marine Sanctuary. The analysis of possibility area of the marine sanctuary was performed with simulated annealing using Marxan. The datasets were used in analysis included geomorphic model of habitat (sea floor), coastal ecosystems, blue swimming crab catches (sample size, location, and fishing pressure). The results obtained three possibility locations of the marine sanctuary, which is around of Laki Island, Southern, and Southeastern of Lancang Island. From the possibility locations, we recommend the first location as the Marine Sanctuary with considering the more diverse of features represented.

Distribusi Spasial Rajungan (Portunus pelagicus) pada Musim Timur di Perairan Pulau Lancang, Kepulauan Seribu

A study was carried out to assess the present status of blue swimmer crab (Portunus pelagicus) in Lancang Island, incorporating identification of fishing ground, also measurement of environmental condition and crab biometry. Monthly catch assessment was performed on JuneSeptember 2015 at three landing bases using structured questionnaire and morphometric sampling of minimum randomly selected 30 crabs. Bathymetric survey was conducted to produce depth-contoured maps combined with certain oceanographic parameters (sea surface temperature, salinity, water clarity, total suspended solids, dissolved oxygen, and nitrate-NO3) measured at 15 sampling sites. A grid map was produced to identify key areas of crab fishing grounds, recruitment habitat, and spawning habitats. During southeast monsoon, main fishing ground was distributed in the western and southern part of Lancang Island (grid C3, C4, and D5). In general, crab yields were dominated by female (66.9%) and 43.8% of them were bearing eggs. Four size classes were determined from frequency distribution of carapace width (Class 1 = 7.010.6 cm; Class 2 = 10.714.2 cm; Class 3 = 14.317.8 cm; and Class 4 = 17.921.5 cm), with Class 2 as the most prominent catch. Referring to ontogenetic migration trait of the species, presumed recruitment habitat for blue swimmer crab in Lancang Island is located at A6, where abundant juveniles were harvested in the area with strong oceanic influence and depth range of 2430 m. Spatial coherence on the distribution of bearing egg female with several environmental parameters (sea surface temperature, salinity, and dissolved oxygen) indicates strong estuarine influence is required for crab spawning habitat at C3 and D5.