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[Penelitian tentang dugaan densitas dan sebaran ikan pelagis dengan kondisioseanografi di perairan barat aceh, telah dilakukan pada tanggal 6 sampai dengan 8 agustus2005 dengan KM. Bawal Putih. Perangkat perum gema ikan menggunakan SIMRAD EK 60dengan frekuensi 120 KHz/Split Beam Acoustic System, untuk pengamatan kondisioseanografi menggunakan CTD model Seabird SBE-119. Tujuan penelitian di arahkan untukmendapatkan dugaan densitas dan sebaran ikan pelagis di kawasan ini serta dihubungkandengan kondisi oseanografi. Luas daerah kajian adalah 4.898,41 km2. Pengamatan secaravertikal dilakukan pada kisaran kedalaman 0 -100 m yang dibagi dalam 10 strata kedalamandengan rentang per strata 10 m. Pengamatan secara vertikal menunjukan bahwa perkiraankelimpahan menurut kisaran kedalaman memperlihatkan nilai yang beragam dimana padakedalaman pada strata 1 (0-10 m) cenderung memberikan nilai kepadatan tertinggi,kemudian menurun dengan pertambahan kedalaman. Pada kedalaman ini suhu berkisar28,68 °C - 29,79 °C dan salinitas 33,17 PSU - 33,62 PSU. Pengamatan secara horizontaldiperoleh jumlah ESDU sebanyak 258 yang dibagi dalam 16 LEG dari seluruh lintasan. Nilaikepadatan tertinggi secara horizontal berada pada perairan Meulaboh yaitu pada LEG 13,14, dan 15, yang mencapai nilai densitas 1752 ekor/1000 m3. Kondisi suhu perairan padawilayah ini lebih hangat dari seluruh daerah penelitian yaitu 29°C (suhu rata-rata 28,5°C) dansalinitas rendah yaitu 33,35 PSU (salinitas rata-rata 33,87 PSU) yang diduga sebagaipengaruh limpasan air dari daratan (sungai-sungai di Meulaboh). Analisis korelasi denganmenggunakan Spearman's rho test menunjukkan adanya hubungan negatif antara parameterkedalaman dan suhu (-0.691) serta densitas ikan (-0.336). Sedangkan kondisi sebaliknyaterjadi untuk parameter kedalaman dan salinitas (r=0.842), hal ini menunjukkan pengaruhyang tinggi dari muara sungai di perairan barat Aceh dimana parameter salinitas bernilailebih rendah di permukaan laut., The utilization of fisheries and maritime resources in Indonesia hasnot been done optimally. Therefore, the information about fisheries andmaritime resources still becomes a serious problem. The exploration offisheries and maritime resources should be supported with science andtechnology in order to determine the accurate, effective, efficient ways inmaintaining the sustainability of the resources. Acoustic method is alreadywellknown as one of the methods in fisheries technology.The observation about Pelagic fish density and distribution usinghydro acoustic as well as observation of oceanography condition in thewestern part of aceh waters conducted on August 6-8, 2005. Theinstruments used are SIMRAD EK 60 with its Split Beam Acoustic System toobserve Pelagic fish density and distribution as well as CTD (ConductivityTemperature Depth) Seabird model SBE-119 for climate and salinityobservation. The collection of data was performed by K.M. Bawal Putihwithin 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 landcondition thus more pelagic fish were found at the neurotic area, whichencompasses water mass lying down on the surface of the continent. Thisarea contains same nutrient derived from coastal area. Because of theshallow depth, the water temperature remained warm.The research results show that the highest average density is locatedon Meulaboh waters (Leg 13, 14, and 15) within the density value about1752 fish/1000 m3. This condition is predicted due to suitable climate andsalinity of waters. The highest temperature was 290 C (temperature average28,50 C) and the lowest salinity 32,82 PSU, it might be happen because ofthe runoff from the river (rivers in Meulaboh).However, vertically, most of the density value tend to decline alongwith 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 thethermo cline layer at level 9 to 10 (80 - 100m) nearly 343 fishes/1000m3. Itscondition can be happened due to the decrease of fish’s tolerant level onphysical 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 sizesdepends on its depth. On first layer, strength target frequency about 60 -dB45 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 seasvertically show the same method. The warm-thick isothermal layer wasobserved between 80 to 120 meters. Horizontally the temperature of seasurface is various from 28,65oC to 30,15oC. The sea surface temperatureincreases gradually form north to south, and show the decrease from coastalarea to Hindia Ocean.Salinity of sea surface on west Aceh seas doesn’t show significantvariation, between 32,8 PUS and 33,7 PSU. The salinity of coast area fromnorth to south relatively low and gradually increases to Hindia Ocean. Thelowest salinity was found near the Meulaboh waters.Correlation analysis using Spearman's rho test shows a negativecorrelation between depth parameter and temperature (-0.691), and densityof fish (-0.336). It means that water temperature and fish density willdecrease in increasing depth. Positive correlation is shown between depthand salinity parameters within number 0.842 it demonstrates that in westernaceh seas, there are a big influence of river discharge to the surroundingarea especially in lower salinity parameter on the surface.] |
T40779-Rahmat Muallim.pdf :: Unduh