Judul: Strategi pengelolaan sumberdaya perikanan rajungan (Portunus pelagicus) untuk pemanfaatan berkelanjutan
Abstrak: Blue swimming crab (Portunus pelagicus) resources is one of high economic value commodity of marine products and numerous in Kolaka Regency waters. Kolaka Regency including in the Bone bay region, in which this region is the second largest contributor (21%) after the northern coast of Java (28%) of the blue swimming crab total production throughout Indonesia since 2001 until 2008. Estimated total blue swimming crab production in Kolaka Regency decreased because of increasing fishing activities, thus requiring a comprehensive study. The purpose of this study: 1) Knowing the potential resources of blue swimming crabs in the Bone bay waters, Kolaka Regency, Southeast Sulawesi Province; 2) Determine the ecological economics sustainability index of the blue swimming crab resources 3) Analyze the feasibility level of catch effort; 4) Determine the strategic management direction of the blue swimming crab resources for sustainable uses. The research shows that the alleged maximum sustainable yield (MSY) of 129 997 kg, optimum fishing effort (fMSY) equal to 21 739 trips. Sustainability index values obtained 1.63 (very good). Catch effort feasible to be developed,the value of NPV = Rp27 857 867, Net B/C = 3.15, and IRR = 60.62%. There are several fishing ground which clashed with the allocation based on local government policy. Blue swimming crab management resources require attention from governments and policymakers and all stakeholders. For that to be implemented management resources policies includes: 1) rescue policies, and (2) utilization policy, in order to create sustainability and obtained an optimal and sustainable utilization.
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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: 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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