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: Ecological Characteristics of Catch by Handline Fisherman Landing based in Harapan Island Kepulauan Seribu
Abstrak: Pancing kotrek merupakan alat tangkap yang digunakan oleh nelayan Pulau Harapan untuk menangkap ikan ekor kuning (Caesio cuning). Kegiatan penangkapan berpotensi menimbulkan dampak negatif terhadap ikan target dan fungsi ekosistem. Penelitian ini bertujuan untuk: mendeskripsikan unit penangkapan pancing kotrek yang berbasis di Pulau Harapan, Kepulauan Seribu; mengestimasi jenis dan keragaman ikan hasil tangkapan pancing kotrek yang berbasis di lokasi studi; dan mengevaluasi dampak penangkapan berdasarkan persentase jumlah ikan layak tangkap menurut spesiesnya dan tingkat trofik hasil tangkapan pancing kotrek yang berbasis di lokasi studi. Hasil penelitian menunjukkan bahwa konstruksi pancing kotrek di Pulau Harapan terdiri dari penggulung, tali utama (main line), tali cabang (branch line), benang, kili-kili (swivel), mata pancing (hook), dan pemberat. Mata pancing yang digunakan yaitu nomor 20. Ikan hasil tangkapan pancing kotrek terdiri dari 13 jenis dengan nilai indeks keragaman Shannon- wiener H’=1,57. Ukuran layak tangkap berdasarkan parameter length at first maturity (Lm) menunjukkan bahwa ikan ekor kuning (Caesio cuning) sebesar 41% layak tangkap, ikan selar como (Atule mate) sebesar 64-91%, dan ikan lemuru (Sardinella lemuru) sebesar 25-92%. Berdasarkan parameter tingkat trofik hasil tangkapan, pancing kotrek didominasi oleh jenis ikan kelompok omnivora cenderung pemakan hewan atau trophic level 3 (TL3). Penelitian ini menunjukkan bahwa walaupun ikan hasil tangkapan pancing kotrek sebagian besar layak tangkap, namun secara ekologis berdampak terhadap struktur dan fungsi ekosistem (ketidakseimbangan rantai makanan)., Handline is a fishing gear maintly used by the fishermen in Harapan Island to catch Redbelly yellowtail fusilier (Caesio cuning). Fishing has a potential negative impact on target fish and ecosystem function. This study aims: to describe the handline fishery based in Harapan Island, Kepulauan Seribu; to estimate species and diversity of catch by handline in this study area; and to evaluate fishing impact base on parameters of biological allowable catch sizes and trophic level of handline in this study area. The study result showed that the handline construction in Harapan Island consisted of a roller, main line, branch line, twine, swivel, hook, and weight. There were 13 fish species caught by handline with Shannon – wiener diversity index value H ' of = 1,57. Biological allowable catch size based on the parameter length at first maturity (Lm) showed that Redbelly yellowtail fusilier (Caesio cuning) has allowable catch size of 41%, Yellowtail scad (Atule mate) of 64-91%, and Bali sardinella (Sardinella lemuru) of 25-92%. Based on the trophic level parameters, the handline catches were dominated by the omnivore group of fish or trophic level 3 (TL3). This study confirm that although most of the handline catches are allowable size, ecologically it has an impact on the structure and function of the ecosystem (food chain imbalance).
Keyword: ecological impact, catch characteristic, Kepulauan Seribu, handline

Judul: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
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