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"ABSTRAKPenelitian tentang keanekaragaman dan pendugaan kepadatan stokikan demersal dengan metode sapuan di perairan Aru, Propinsi Maluku,dilakukan sejak tanggal 4 sampai 9 Nopember 2006, menggunakan pukatdasar (bottom trawl). Pengambilan data dilakukan melalui survei pukatdasar menggunakan KR. Bawal Putih dengan lokasi pengambilan contohditetapkan sebanyak 36 stasiun. Penelitian ini bertujuan untuk mengetahuiindeks keanekaragaman (H?), indeks dominansi spesies (C), indekskemerataan (J), komposisi hasil tangkapan, laju tangkap, pendugaankepadatan stok, dan biomassa spesies ikan demersal. Hasil penelitianmenunjukkan bahwa komposisi hasil tangkap ikan demersal adalah 65,9 %(6.065,9 kg) dari total hasil tangkap, yang terdiri dari 132 spesies dan 56famili. Ikan demersal yang banyak tertangkap adalah famili Leiognathidae(50,8%) diikuti Apogonidae (16,5%) dan Mullidae (8,3%). Tiga spesies yangbanyak tertangkap yaitu Leiognathus bindus (26,3%) Apogon sp.(16,5%)dan Leiognathus leusiscus (15,8%) yang umumnya tertangkap pada dasarperairan dengan kedalaman 20-30 m.Kisaran indeks keanekaragaman (H?) adalah 0,4940-2,5138 dengannilai tertinggi pada kedalaman 40-50 m, indeks dominansi (C) adalah0,0618-0,8041 dengan nilai tertinggi pada kedalaman 10-20 m, danindeks kemerataan (J?) adalah 0,0553-0,4236 dengan nilai tertinggi padakedalaman 40-50 m sehingga dapat dikatakan bahwa keanekaragaman spesies ikan demersal di perairan Aru adalah sedang dengan tidak adaspesies yang mendominasi dan penyebarannya tidak merata.Nilai laju tangkap ikan demersal adalah 173,2 kg/jam dengan nilailaju tangkap tertinggi pada perairan di kedalaman 20-30 m, (Leiognathusbindus 27,1 kg/jam tertinggi pada kedalaman 20-30 m, Apogon sp. 18,8kg/jam tertinggi pada kedalaman 50-60 m, dan Upeneus sulphureus 8,9kg/jam pada kedalaman 20-30 m; Arius thalassinus 87,4 kg/jam tertinggipada kedalaman 30-40 meter, Lutjanus malabaricus 12,2 kg/jam,kedalaman 50-60 meter tertinggi, dan Epinephelus sexfaciatus 6,9 kg/jam,tertinggi di kedalaman 40-50 meter). Dugaan kepadatan stok ikandemersal di perairan Aru adalah 4,4±0,2 ton/km2 (Leiognathus bindus, 0.7ton/km2, Apogon sp. 0,5 ton/km2, dan Upeneus sulphureus 0,2 ton/km2;Arius thalassinus 2,4 ton/km2, Lutjanus malabaricus 0,3 ton/km2, danEpinephelus sexfaciatus 0,2 ton/km2). Total biomassa ikan demersal diPerairan Aru diduga adalah sebesar 193.975±257 ton (Leiognathusbindus, 29.076 ton, Apogon sp. 20.769 ton, dan Upeneus sulphureus10.138 ton; Arius thalassinus 0,2 ton, Lutjanus malabaricus 0,1 ton, danEpinephelus sexfaciatus 0,1 ton)."

"The utilization of fisheries and maritime resources in Indonesia has not been done optimally. Therefore, the information about fisheries and maritime resources still becomes a serious problem. The exploration of fisheries and maritime resources should be supported with science and technology in order to determine the accurate, effective, efficient ways in maintaining the sustainability of the resources. Acoustic method is already wellknown as one of the methods in fisheries technology. The observation about Pelagic fish density and distribution using hydro acoustic as well as observation of oceanography condition in the western part of aceh waters conducted on August 6-8, 2005. The instruments used are SIMRAD EK 60 with its Split Beam Acoustic System to observe Pelagic fish density and distribution as well as CTD (Conductivity Temperature Depth) Seabird model SBE-119 for climate and salinity observation. The collection of data was performed by K.M. Bawal Putih within covering area approximately 5 mile, the distance from coastal area to the offshore is about 35 mile, and 4.898 area of research width in total. The horizontal distribution of pelagic fish is mostly influenced by land condition thus more pelagic fish were found at the neurotic area, which encompasses water mass lying down on the surface of the continent. This area contains same nutrient derived from coastal area. Because of the shallow depth, the water temperature remained warm. The research results show that the highest average density is located on Meulaboh waters (Leg 13, 14, and 15) within the density value about 1752 fish/1000 m3. This condition is predicted due to suitable climate and salinity of waters. The highest temperature was 290 C (temperature average 28,50 C) and the lowest salinity 32,82 PSU, it might be happen because of the runoff from the river (rivers in Meulaboh). However, vertically, most of the density value tend to decline along with the increase of depth, the highest density occur on level 1 (1 to 10 m) about 1745 fishes /1000 m2, whereas the lowest density found on the thermo cline layer at level 9 to 10 (80 - 100m) nearly 343 fishes/1000m3. Its condition can be happened due to the decrease of fish’s tolerant level on physical condition of thermo cline layer such as: temperature effect, salinity, intensity of light and also the decrease of food supplies. Target Strength data indicated that the different variation of fish sizes depends on its depth. On first layer, strength target frequency about 60 -dB 45 Db dominated the waters, it explains that the first level is dominated by small Pelagic fish or others but it has smaller size than deep water fish. Strength target value which is relatively lower was found on near-shore area, while the higher target is quite far from the coastal area. The value of temperature and salinity in the western part of Aceh seas vertically show the same method. The warm-thick isothermal layer was observed between 80 to 120 meters. Horizontally the temperature of sea surface is various from 28,65oC to 30,15oC. The sea surface temperature increases gradually form north to south, and show the decrease from coastal area to Hindia Ocean. Salinity of sea surface on west Aceh seas doesn’t show significant variation, between 32,8 PUS and 33,7 PSU. The salinity of coast area from north to south relatively low and gradually increases to Hindia Ocean. The lowest salinity was found near the Meulaboh waters. Correlation analysis using Spearman's rho test shows a negative correlation between depth parameter and temperature (-0.691), and density of fish (-0.336). It means that water temperature and fish density will decrease in increasing depth. Positive correlation is shown between depth and salinity parameters within number 0.842 it demonstrates that in western aceh seas, there are a big influence of river discharge to the surrounding area especially in lower salinity parameter on the surface."