Judul: Perikanan bubu dasar di Kabupaten Bangka Selatan Provinsi Kepulauan Bangka Belitung
Abstrak: Bottom traps is a main type of fishing gears which is used in the capturing reef fish on South Bangka Regency. This study was aimed to indentify and quantify soaking time of bottom trap which was made from wire and net to fish catches, to determine feasibility of bottom traps business on South Bangka Regency.The methods in this research were experimental fishing and descriptive survey. Fish catching was analyze using krebs formula. In addition, the influence of different traps material to fish cathing was analyze using randomized block design and feasibility of bottom traps business was analized using financial analysis. The results showed that bottom wire trap and bottom net trap were dominatedby Lutjanus johni and leopard coral grouper (24 pieces). Total weight of fish catchingfrom bottom net trap was 90.05. Meanwhile, total weight of fish catches from bottom wire trap was 82.58 kg. Based on soaking time, the highest total amount was obtained from 5 days soaking (71.59 kg), 3 days soaking (47.08 kg), and 4 days soaking (47.08 kg), respectively,so time soaking gave effect to total amount of fish catching. Rate of return on bottom wire traps was IDR 9,465,507.93 / year and R/C value was 1.05. In addition, rate of return on net bottom traps was IDR 26,662,429.00 / year and R/C value was 1.10.Reffering to investment criterias, NPV of bottom wire traps business was obtained IDR 132,093,915.15, meanwhile NPV of bottom net traps business was obtained IDR 314,926,267.14.
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Judul: The Impact of Trap and Fishing Lines on Fish  Resources in the Waters of Harapan Island, Kepulauan Seribu, Jakarta
Abstrak: Penggunaan bubu dan pancing di Perairan Pulau Harapan Kepulauan Seribu mengakibatkan ikan juvenile banyak tertangkap. Hal ini karena bubu tidak memiliki celah pelolosan ikan dan pada pancing ukuran mata pancing terlalu kecil. Intensitas penangkapan ikan yang semakin tinggi dapat berdampak negatif bagi kelestarian stok ikan dan keseimbangan rantai makanan. Penelitian ini bertujuan untuk mendeskripsikan konstruksi alat tangkap bubu dan kelompok pancing (pancing ulur, pancing kotrek, dan pancing rawai) yang berbasis di Pulau Harapan, Kepulauan Seribu; mendeskripsikan karakteristik hasil tangkapan bubu dan kelompok pancing (spesies, ukuran layak tangkap, jumlah individu, dan komposisi) di Perairan Kepulauan Seribu, khususnya yang didaratkan di Pulau Harapan; dan mengestimasi dampak perikanan bubu dan kelompok pancing terhadap ikan target dan keseimbangan rantai makanan. Hasil penelitian menunjukkan bubu kawat memiliki panjang 137 cm, lebar 97 cm, dan bukaan mulut 35 cm. Kail pancing yang digunakan adalah kail pancing nomor 7. Kapal yang digunakan pada kedua alat tangkap ini yaitu kapal fiber. Nilai indeks keragaman Shannon-Wiener tangkapan alat tangkap bubu sebesar 2,56 dan pada pancing sebesar 0,77. Ikan yang memiliki nilai panjang pertama kali matang gonad (Lm) sama dengan metadata fishbase yaitu ikan pisang-pisang (Lutjanus vitta) dengan porsi ukuran layak tangkap sebesar 70%. Ikan kerapu lumpur (Epinephelus coioides), Ikan tenggiri (Scomberomorus commerson), dan ikan baronang garis (Siganus javus) memiliki nilai Lm penelitian lebih kecil dibanding metadata fishbase. Tangkapan ikan didominasi tingkat trofik TL3 dan TL2. Secara teori, jika hal ini terus berlanjut akan mengancam keberlanjutan sumberdaya ikan pada semua tingkat trofik (rantai makanan)., The use of traps and fishing lines in the waters of Harapan Island, Kepulauan Seribu resulted in many juvenile fish being caught. This is because the trap does not have a gap for the fish to escape and the hook size is too small on the fishing line. Higher fishing intensity have a negative impact on the sustainability of fish stocks and the balance of the food chain. This study aims to describe the construction of trap fishing gear and fishing lines (handline, hook and line, and longline) based on Harapan Island, Kepulauan Seribu; to describe the characteristics of traps and fishing lines catches (species, allowable catch size, number of individuals, and composition) in the Kepulauan Seribu waters, especially those landed on Harapan Island; and estimating the impact of trap fisheries and fishing lines group on target fish and the balance of the food chain. The results showed that the wire traps had a length of 137 cm, a width of 97 cm and a mouth opening of 35 cm. The fishers used a fishing hook with number of 7. The ship used for these two fishing gears was a fiber boat. The Shannon-Wiener diversity index value for trap catches was 2.56 and for fishing lines was 0.77. The fish with the length at first maturity (Lm) was similar with Fishbase metadata, i.e. Brownstripe red snapper (Lutjanus vitta) with an allowable catch size portion of 70%. Orange-spotted grouper (Epinephelus coioides), Narrow-barred Spanish mackerel (Scomberomorus commerson), and Streaked spinefoot (Siganus javus) were a smaller Lm values than Fishbase metadata. The fish catches were dominated by the catches of TL3
Keyword: Wire traps, Fishing lines, Fishing impact, Allowable catch size, Trophic  level

Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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