Judul: Tuna Fisheries Production and Fishers' Welfare at Binuangeun Fish Landing Base (PPI) Banten
Abstrak: Produksi perikanan tuna dan kesejahteraan nelayan di Pangkalan Pendaratan Ikan (PPI) Binuangeun penting untuk diketahui sebagai dasar penentuan kebijakan peningkatan kesejahteraan nelayan dengan tetap memperhatikan kelestarian sumberdaya tuna. Penelitian ini bertujuan menganalisis produksi dan produktivitas perikanan tuna, status pemanfaatan sumberdaya tuna, dan kesejahteraan nelayan tuna di PPI Binuangeun. Pengumpulan data primer dilakukan melalui wawancara pengisian kuisioner dan pengamatan lapangan. Analisis data berupa analisis produksi, produktivitas, potensi lestari maksimum, status pemanfaatan, sistem bagi hasil, dan kesejahteraan nelayan. Produksi dan produktivitas perikanan tuna mengalami peningkatan secara kontinu. Status pemanfaatan sumberdaya tuna tergolong fully-exploited pada tahun 2018 hingga 2020 dan over-exploited pada tahun 2021 karena melebihi potensi lestari maksimum sebesar 210 ton/tahun. Tingkat kesejahteraan nelayan perikanan tuna tergolong tinggi untuk seluruh nakhoda, sedangkan untuk ABK sebanyak 87% tergolong kesejahteraan tinggi dan 13% ABK lainnya tergolong kesejahteraan sedang., Tuna fisheries production and fishers welfare at Binuangeun Fish Landing Base (PPI) are important to know as a basis for policy making to enhancing the welfare of tuna fishers while also ensuring the sustainability of tuna resources. This study aims to analyze the production and productivity of tuna fisheries, the status of tuna resource utilization, and the welfare of tuna fishers at PPI Binuangeun. Primary data was collected through interviews, questionnaires and field observations. Data analysis in the form of production analysis, productivity, maximum sustainable potential, utilization status, profit sharing system, and fishers welfare. The production and productivity of tuna fisheries have increased continuously. The status of tuna resource utilization is classified as fully-exploited in 2018 to 2020 and over-exploited in 2021 because it exceeds the maximum sustainable yield of 210 tons/year. The welfare level of tuna fishers is classified as high for all captains, while for crew members, 87% are classified as high welfare and 13% of other crew members are classified as medium welfare.
Keyword: fisheries production, fishers welfare, maximum sustainable yield, tuna

Judul: Kajian Bioekonomi Perikanan Rawai Tuna di PPN Palabuhanratu, Sukabumi, Jawa Barat
Abstrak: High demand and production of tuna fish in PPN Palabuhanratu has caused exploitation of tuna increased and potentially affect the biological condition and sustainability of fishing business. This study aimed to know biological condition, utilization status, and optimum management of tuna fish resources. Diversity index of shannon-wiener (H’), length at first maturity, length-weight relationships, and bioeconomy model was used in this study for data analyses. Result of this study show that the H’ value was 1.60-2.42. Based on the length at first maturity parameter, 3.84 - 41.02 % for bigeye tuna, 0.72% for yellowfin tuna, and 65.63% for swordfish was lower than unallowable catch size. The length-weight relationships of bigeye and yellowfin tuna were indicated negative allometric growth model, whereas swordfish positive allometry. Actual effort of tuna fishery in PPN Palabuhanratu was not indicated a biological overfishing condition, however it indicated an economical overfishing condition. Bioeconomy optimalization was achieved at fishing effort of 597 trips, production of 2481.14 tons, and economic rent of Rp 67.704.000.000,-.
Keyword: PPN Palabuhanratu, tuna longline, tuna, bioeconomy

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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