Judul: The Stock Status of Scalloped Spiny Lobster (Panulirus homarus) in Palabuhanratu Waters Using the Spawning Potential Ratio method
Abstrak: Nelayan Palabuhanratu banyak menangkap lobster terutama lobster pasir (Panulirus homarus). Pendataan yang kurang terkait stok lobster bisa berdampak pada keberlanjutan lobster di perairan Palabuhanratu. Penggunaan metode spawning potential ratio (SPR) bisa menjadi solusi dalam menentukan harvest strategy lobster. Penelitian ini bertujuan untuk mengidentifikasi unit penangkapan lobster, mengidentifikasi komposisi hasil tangkapan lobster, menghitung parameter biologi lobster, dan menentukan status pemanfaatan lobster. Pendekatan length base spawning potential ratio (LB-SPR) digunakan untuk pengolahan data. Analisis deskriptif dan kualitatif digunakan dalam menganalisis data yang didapatkan. Hasil penelitian menunjukkan bahwa kapal yang digunakan untuk menangkap lobster berukuran 2-3 GT dan 5 GT. Alat tangkap berupa gillnet dan trammel net. Lobster yang tertangkap ada 4 jenis yaitu lobster pasir, lobster mutiara, lobster bambu dan lobster batu. Hasil penelitian didapatkan panjang asimptotik (L∞) lobster pasir jantan dan betina sebesar 110,5 mm dan 106,67 mm. Koefisien pertumbuhan (K) untuk lobster jantan dan betina sebesar 0,34/tahun dan 0,44/tahun. Nilai laju eksploitasi (E) lobster pasir jantan dan betina sebesar 0,74 dan 0,80 dengan rata-rata panjang lobster matang gonad (Lm) sebesar 58,21. Nilai spawning potential ratio (SPR) lobster pasir diperoleh sebesar 12,63% dimana hasil tersebut kurang dari 20% yang artinya status pemanfaatan lobster di perairan Palabuhanratu sudah terjadi tangkap lebih (overfishing), In Palabuhanratu, fishers catch a lot of lobsters, particularly the scalloped spiny lobster (Panulirus homarus). The sustainability of lobsters in Palabuhanratu waters may be impacted by inadequate data collection on lobster stocks. Using the spawning potential ratio (SPR) approach will contribute to Harvest Strategy for Lobster Fishery in that area. The objectives of this study are to identify lobster fishing units, characterize lobster captures, compute biological parameters for lobsters, and assess the utilization of lobsters. Data processing uses the length-based spawning potential ratio (LB-SPR) method. The data were analyzed using descriptive and qualitative methods. The findings revealed that the size of the lobster-catching vessels was 2-3 GT and 5 GT. Gillnets and trammel nets are two types of fishing gear. Four different kinds of lobsters were caught: scalloped spiny lobsters, ornate spiny lobsters, bamboo lobsters, and pronghorn spiny lobsters. The findings revealed that the asymptotic lengths (L) of male and female scalloped spiny lobsters were 110.5 mm and 106.67 mm, respectively. Male and female lobsters’ growth coefficients (K) are 0.34 and 0.44 per year. An average scalloped spiny lobster's gonadal mature length (Lm) was 58.21 inches, and its exploitation rate values (E) were 0.74 and 0.80 for males and females, respectively. The scalloped spiny lobster's spawning potential ratio (SPR) value was 12.63%, which is below the 20% threshold, indicating overfishing of the species in the waters around Palabuhanratu.
Keyword: harvest strategy, lobster pasir, Palabuhanratu, spawning potential ratio (SPR), status pemanfaatan

Judul: Utilization Status of Scalloped Spiny Lobster (Panulirus homarus) in Coastal Waters Ayah Kebumen
Abstrak: Keberlanjutan menjadi salah satu isu penting dalam pemanfaatan sumberdaya lobster. Ketersediaan data menjadi faktor pembatas untuk mengetahui status pemanfaatan lobster khususnya lobster yang dominan ditemukan di Perairan Pantai Ayah, Kabupaten Kebumen yaitu lobster pasir (Panulirus homarus). Pendekatan length base spawning potential ratio (LB-SPR) digunakan untuk menentukan status pemanfaatan lobster. Penelitian ini bertujuan mendeskripsikan unit penangkapan lobster, mengidentifikasi komposisi ukuran hasil tangkapan lobster, dan menghitung parameter biologi lobster untuk mengetahui status pemanfaatan lobster pasir (Panulirus homarus). Data ukuran panjang karapas lobster dikumpulkan dengan metode accidental sampling. Analisis yang digunakan yaitu analisis deskriptif, analisis pertumbuhan, mortalitas, laju eksploitasi, pola rekruitmen dan spawning potential ratio. Hasil penelitian menunjukkan bahwa, panjang asimptotik lobster pasir jantan dan betina sebesar 120,75 mm dan 120,11 mm. Nilai koefisien pertumbuhan lobster pasir jantan dan betina yaitu sebesar 0,47 dan 0,40 per tahun. Nilai laju mortalitas baik lobster pasir jantan dan betina yaitu 0,75 dan 0,68 per tahun. Laju eksploitasi lobster pasir jantan dan betina sebesar 0,46 dan 0,38. Rata-rata ukuran panjang karapas lobster pasir yang tertangkap sebesar 79,37 mm termasuk dalam ukuran sudah layak tangkap. Status pemanfaatan lobster pasir (Panulirus homarus) di perairan Pantai Ayah Kabupaten Kebumen sebesar 36% yang artinya lestari., Sustainability is an important issue in the utilization of lobster resources. However, the availability of data is a limiting factor to determine the status of lobster utilization. Scalloped spiny lobster (Panulirus homarus) is dominantly found in the Ayah Coastal Waters, Kebumen Regency. The length base spawning potential ratio (LB-SPR) used to determine the status of lobster utilization. This study aims to describe lobster fishing units, to identify the size composition of lobster catches, and to calculate lobster biological parameters for determining the utilization status of Panulirus homarus. Length data of lobster carapace were collected by accidental sampling method. The research were applied descriptive analysis, analysis of growth, mortality, exploitation rate, recruitment pattern and spawning potential ratio. The results showed that there was a asymptotic lengths of male and female Panulirus homarus by 120,75 mm and 120,11 mm, respectively. In addition, the growth coefficient value of male and female Panulirus homarus was 0,47 and 0,40 per year. Furthermore, the mortality rate values for both male and female lobster were 0,75 and 0.68 per year; the exploitation rate of male and female was 0,46 and 0,38. Moreover the average carapace length caught of them were 79,37 mm, which was included in the legal size for catching. These result found that the utilization status of Panulirus homarus in the Ayah Coastal Waters, Kebumen Regency was 36%, which means fully moderate.
Keyword: Scalloped Spiny Lobster, Kebumen waters, Panulirus homarus, spawning potential ratio (SPR), utilization status

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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