Judul: Pengelolaan Berkelanjutan Perikanan Rajungan (Portunus pelagicus) di Lampung Timur.
Abstrak: Increasing demand for crab meat export and followed by good prices have been increased fisher preference for capturing the blue swimming crab, Portunus pelagicus (Linnaeus, 1758) in Indonesia. One of potential area for wild catch production of this species in Indonesia was at the East Lampung coastal waters, which is an open coast type with generally slight slope of marine topography. However, biological information of this species was rare. Catches productivity as well as caught crabs sizes tend also to be decreased and might be related to high exploitation rate; so this fishery is required to be managed properly. This study aimed to: (1) describe life history characteristics in reproductive biology; (2) distinguish spatial temporal variation of stock structure; (3) describe population dynamic parameters; (4) evaluate of crab exploitation pattern; (5) arrange management measure options for sustainable management of this crab fishery in East Lampung coastal waters. A comprehensive reproductive biology parameters were analysed based on representative samples, which were collected at landing site and conducted monthly from June 2011−Mei 2012. Spatio-temporal of stock structure was analysed based on sampling at three stratifications area from March 2012−February 2013. These stratification areas consist of S1 (water depth <5 m and <4 nautical mile from the shore line), S2 (water depth about 5−10 m and 4−10 nautical mile from the shore line), S3 was offshore direction, whiles fourth sub-areas (A1−A4) at each stratification. Those sub-areas were decided based on morphological characteristics of shore and coastal land coverage. Thus, the unit area of sampling was noted as S1A1−S3A4. Those above samples were also used for population dynamic parameter analysis. Crab exploitation pattern was investigated by interviewing the fishers and guided by questionnaire during December 2012−February 2013 and June−September 2013. Life history characteristics of this species in this area indicated by: (a) the size of males and females reach gonad maturity 50% (Lm50)were at 98 mm and 103 mm carapace width (CW); (b) female’s Lm75 and Lm95 were at the size 111.6 mm and 126.0 mm CW, while reproductive maturity (Lr50) was at 115 mm CW; (c) berried females (BEF) ovaries have dominated by gonad development stage of III; (d) gonad somatic indexes of nonberried female (NBF) were higher than BEF in each month, except in August, November, and February, indicating multiple spawning in the year; (e) females became double breeding or more in the year as well as high potential for spawning and the value of relative percentage of BEF/NBF above 30% at the size larger than 111 mm CW; (f) the potentially reproductive females at the size 111−170.99 mm and reproductively females at 111−155.99 mm CW. Reproductive pattern was partially spawner and spawning occurred thorough in the year, but it was seasonal-continuous with two peaks season. The first peak of spawning season tends during April−June and the second peak was during September− October/November. Both peaks of spawning seasons vary in BEF abundance and fecundity. Fecundity at the 1st stage of embryonic development with BEF’s size between 91.58−168.00 mm CW was between 229,4682,236,355 eggs (mean ± SE = 926,638 ± 30,975 eggs), linearly and positive
Keyword: East Lampung, Blue swimming crab, harvest strategy, population biology, sustainable management

Judul: Status of Utilization and Impact of Fishing on Blue Swimming Crab (Portunus pelagicus) Resources in Lamongan Water, East Java
Abstrak: Hasil tangkapan rajungan (blue swimming crab) dimanfaatkan dan berkontribusi cukup besar pada sektor perikanan dan kelautan terutama sebagai komoditi ekspor ke negara tujuan seperti USA mencapai 73% dan beberapa negara lainnya. Sentra perikanan rajungan di WPPNRI 712 khususnya Lamongan memiliki rata-rata nilai produksi sebesar 46 miliar rupiah per tahun. Saat permintaan ekspor tinggi dan harga jual rajungan tinggi, memicu nelayan untuk meningkatkan intensitas penangkapan rajungan. Stok sumberdaya rajungan di alam cenderung makin berkurang, banyak tertangkapnya bycatch, bahkan telah terjadinya overfishing di beberapa lokasi. Besarnya tangkapan non target (bycatch) dapat berdampak serius bagi sumberdaya perikanan, baik secara langsung maupun tidak langsung terhadap ekosistem. Oleh karena itu perlu adanya pengelolaan yang baik agar stok sumberdaya rajungan di alam tetap terjaga. Dalam rangka implementasi Rencana Pengelolaan Perikanan (RPP) Rajungan Indonesia serta strategi pemanfaatan (harvest strategy) perikanan rajungan khususnya di WPP 712, maka dilakukan monitoring secara berkala. Parameter Length Based Spawning Potential Ratio (LB-SPR) merupakan indikator utama yang digunakan untuk mengevaluasi status stok rajungan. Sementara itu dampak penangkapan terhadap non target dimonitor berdasarkan struktur bycatch. Hal tersebut merupakan landasan pentingnya penelitian ini. Penelitian ini bertujuan mendeskripsikan unit penangkapan rajungan, mengevaluasi status pemanfaatan sumberdaya rajungan dan dampak ekologis kegiatan penangkapan rajungan terhadap target (rajungan) dan non target di Perairan Lamongan, Jawa Timur. Penelitian ini dilakukan dengan metode observasi, survei, dan studi literatur untuk mendapatkan data dan informasi terkini sesuai dengan tujuan penelitian. Metode survei dengan melakukan wawancara terhadap 60 responden yang diperoleh melalui purposive sampling method untuk mengetahui informasi unit penangkapan rajungan. Sebanyak 3600 individu sampel rajungan dari alat tangkap bubu, arad, dan trammel net diperoleh melalui metode cluster sampling. Sementara itu bycatch dari ketiga alat tangkap tersebut dikumpulkan melalui simpel random sampling. Pengolahan data menggunakan perangkat lunak microsoft excel dan R-Studio packages LB-SPR dan TropFishR. Analisis data ditujukan untuk mendeskripsikan unit perikanan rajungan, status pemanfaatan rajungan, dan dampak ekologis terhadap target dan non-target di Perairan Lamongan, JawaTimur. Hasil penelitian menunjukkan terdapat 456 unit arad, 25.625 unit bubu, 364 unit trammel net, 3598 nelayan, dan 1424 unit perahu di lokasi studi. Sebaran ukuran sampel rajungan betina 52 – 157 mm, sedangkan jantan 57 – 161 mm. sifat pertumbuhan rajungan jantan dan betina yaitu allometrik positif. Parameter biologi rajungan betina memiliki nilai L∞ = 156,95 mm, K = 1,34 per tahun, M = 1,4 per tahun, dan E = 0,69, sedangkan pada rajungan jantan L∞ = 167,58 mm, K = 1,17 per tahun, M = 1,4 per tahun, dan E = 0,72. Nilai parameter SPR rajungan sebesar 23% atau menunjukkan bahwa status stok sumberdaya rajungan di iv Perairan Lamongan memiliki status fully moderately. Komposisi hasil tangkapan rajungan pada bubu, trammel net, dan arad berturut-turut 90%, 35%, dan 19% serta hasil tangkapan sampingan menggunakan bubu 10%, trammel net 65% , dan arad 81%. Komposisi bycatch berdasarkan jenis hasil tangkapan bubu didominasi oleh keong macan (Babylonia spirata) sebanyak 61 individu, arad oleh teri gelagar (Stolephorus indicus) 1866 individu, dan trammel net oleh mata belo (Hilsa kelee) 327 individu. Indeks keragaman Shannon – Wiener (H‟) untuk bubu, arad, dan trammel net berturut-turut 3,09; 3,63; dan 5,04. Penelitian ini merekomendasikan: 1) pemerintah
Keyword: Blue swimming crab, bycatch, crab fishing unit, fishing impact

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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