Judul: Spatio-Temporal Utilizations, Environmental Parameters and Diversity of Grouper in Saleh Bay
Abstrak: Saleh Bay is a fishing area for local people, especially fishermen in Sumbawa and its surroundings. One of the reef fish resource commodities caught is grouper. However, the productivity of reef fish and demersal fish in Saleh Bay has decreased, leading to an overfishing status. Fishermen catch fish on a large scale, juvenile-sized grouper are caught, and there are indications of catching fish using fishing gear that is not environmentally friendly, such as bombs and potassium. In addition, several locations in the waters of Saleh Bay have been designated as marine conservation areas, so monitoring the utilization of the grouper fish resources is necessary. Therefore, this study aims to identify grouper fishing units, grouper utilization status and grouper fishing intensity in each fishing area, analyze grouper diversity (Shannon-Wiener index, Simpson index, Margalef index, and Pielou index), and the condition of environmental and ecological parameters of grouper in Saleh Bay. This research was conducted in Saleh Bay, Sumbawa, West Nusa Tenggara, sample were taken from February to April 2021. Data on fish landings used included production, number of individuals, fishing gear, fishing effort, and coordinates of fishing areas. The environmental parameter data used is AQUA MODIS satellite image data, including sea surface temperature, chlorophyll-a, and currents. The analytical techniques in this study are descriptive analysis, catch per unit effort, spatial-temporal analysis, the diversity indices (Shannon-Wiener index, Simpson index, Margalef index, and Pielou index), and trophic level. The results show that the grouper fishing fleet in Saleh Bay is a small-scale fishery with fishing gearsuch as bottom longline, troll-line, hand-line, and speargun. The trend of grouper resource utilization tends to increase, and fishing efforts positively influence grouper production in Saleh Bay. Based on CPUE and Fishing Power Index values, the order of the most effective fishing gear used to catch grouper is bottom longline, troll-line, hand-line, and speargun. The grouper fishing ground carried out by fishermen is divided into several locations: Liang Island, Ngali Island, Dempu Island, Lipan Island, Raft Island, and Nusa Pudu Island. The highest fishing intensity occurred around Liang Island, Ngali Island, and Rakit Island. The high intensity of fishing was indicated by the number of fishing operations and the CPUE value in the fishing ground. In the long term, it can lead to the degradation of the grouper population. In addition, fishermen are still catching fish around Liang Island, Lipan Island, and Rakit Island, some of whose water areas have been designated conservation areas. So, increasing supervision in managing grouper fisheries in Saleh Bay is necessary. The environmental conditions of the waters consisting of currents, sea surface temperature, and chlorophyll-a indicate that from July to September, the waters of Saleh Bay experienced an increase in water fertility. The sea surface temperature from July to September ranges from 27.9℃ to 29.4℃. The chlorophyll-a concentration from July to September ranged from 0.13mg/m to 9.05 mg/m³. Fertile waters will be used by phytoplankton, phytoplankton is eaten by zooplankton, small fish eat zooplankton, and small fish eat by big fish to top predators to create a food chain in these waters. Groupers were top
Keyword: Catch per Unit Effort, Fishing Ground, Grouper, Spatial-temporal, Saleh Bay

Judul: Growth exploitation rate and reproduction sunu grouper fish (Plectropomus leopardus) in the Waters of Kolaka Regency, Southeast Sulawesi
Abstrak: Sunu grouper fish is one of the important fishery resources in the water of Kolaka Regency, Southeast Sulawesi. The grouper fishing activities in 2008 – 2011 experienced a production decline of 45%. This study was aimed to study the growth, exploitation rate, maximum sustainable yield, and reproduction of sunu grouper fish. The data were collected in January to June 2012. The growth and exploitation rate were analyzed using FISAT. The Maximum sustainable yield were determined by the Schaefer model of Surplus Production. The first mature size of gonads was measured by using the Sperman Karber equation and the gonad somatic indeks was calculated using Effendie equation. The analysis result showed von Bertalanffy growth coefficient L∞ 92,4 cm, K 0,75/year and t0 -0,15. The exploitation rate of 70%/year is categorized into an overexploited condition. The total allowable catch is 882 tones/year. The first mature size of female and males gonads was 35,9 cm and 69,5 cm respectively.
Keyword: 

Judul: Invers dari Matriks Tridiagonal Jacobi
Abstrak: Suatu matriks berukuran n×n dinamakan matriks tridiagonal jika untuk . Karya ilmiah ini memberikan algoritma yang mudah untuk menemukan invers ( dari matriks tridiagonal Jacobi yang simetrik dan nonsimetrik. Setiap elemen pada matriks tridiagonal ini adalah bilangan real. Terdapat 3 lema dan 2 teorema untuk menentukan . Lema pertama menunjukkan persamaan utama dalam membuktikan lema-lema dan teorema-teorema selanjutnya. Invers dari matriks yang simetrik dibuktikan oleh lema kedua yang menunjukkan elemen-elemen baris ke- dari . Selanjutnya, lema kedua dilengkapi dengan teorema pertama yang menunjukkan elemen-elemen dengan . Invers dari matriks yang nonsimetrik dibuktikan oleh lema ketiga yang menunjukkan elemen-elemen dengan dan elemen-elemen dengan dibuktikankan oleh teorema kedua.
Keyword: symmetric, nonsymmetric, matrix