| dc.description.abstract | Technology development of light fishing using incandesent light bulb on a lift net boat in Kao Bay was expected to increase the fish catch. But in fact, when light fishing was operated on the lift net, it remain not have the maximum catch. This problem was caused due to the limited fishing knowledge of the fishermen in utilizing the light towards the targeted fish behaviour. Fishing effort that has been done by the fishermen in Kao Bay in order to maximize the light utilization was by covering the upper part of the bulb with various types of bowl or pan. The goal was to focus the illumination to the lift net. This was done by them without scientific study whereas centralizing scattered light must be done with theoretical calculation and scientific evidence. This bulb cover utilization usually applied in every fishing operation either in bright or dark moon condition. This research objective was to fix the bulb cover by equipping it with a layer of reflector. The illumination was directed to the lift net at two and five meter distance. As a result, each reflector here the opening angle αr23,3° and αr32,6°. The objective of this research was to determine the organism gathering speed below the covered and reflectored light bulb during the hauling in the full and dark moon period, to find out the light bulb reflector which might give the most catch result during the squids and fish kinds hauling and to determine the effective hauling time during the squids and fish kinds hauling operation. Research phases were conducted in two kinds i.e. the laboratory and field scale. At the laboratory research, the reflector was designed and fabricated. Furthermore, the light intensity measurement towards the covered bulbs -- referred as standard cover-- and reflector. Research continued by testing all three kinds of cover on the field by utilizing three lift net boat from local fishermen. Lift net boat that equipped with standard bulb cover was served as control, while the other two reflectors was utilized as treatment. In the third test the bulb cover was used as experimental method. The operation of lift net was conducted in 24 nights which was divided into two moon periods. During the first 14 nights or bright moon period, lift net was focused to catch squids. Hauling time was done twice between 20.00-01.00 WIT and 01.00-05.00 WIT. The lift net operation that was used for catching fish kinds performed on the following 10 nights in dark moon period. Two hauling times were set between 20.00-00.00 WIT and 00.00-05.00 WIT. The fish behaviour below the lift net was observed with visually and acoustically in every lift net operation. Visual observation was done towards existing organisms on the water surface to a depth of two meter. Meanwhile the acoustic observation was conducted to observe the organism activity at the depth of more than two meter. Result was analyzed in descriptive comparative way based on the light bulb cover type. The catch result that was hauled by the lift net was displayed in the form of numbers and graphs which as next being analyzed in descriptive comparative to see the effectiveness of the bulb cover utilization towards the obtained catch result. Statistical analysis was used to see the influence of the various light bulb cover towards the catch, and the interaction between various light bulb cover to the catch time interval towards the catch result. From this research, result showed that the 300 watt incandesent light bulb spread the light unevenly. The highest light intensity reached 676 lux and the lowest 60 lux. Furthermore, light distribution pattern that came from the standard cover forming a 60o angle and resulted light intensity as much as 961 lux high and 60 lux low. The highest light intensity of the αr23,3° reflectored light resulted 1.561 lux and the lowest is zero lux resulting distribution pattern that formed a 60o angle. As for the highest light intensity the αr32,6o reflectored light resulted 1.278 lux and the lowest is zero lux resulting distribution pattern that formed an 120o angle. With these various light bulb cover utilization it was evident that light intensity has increased. Fishfinder transducer recording proofed that the time for squids to gather below the lift net boat at the depth of more than two meter took about 20 minutes, meanwhile the other types of fish was about 10 minutes. The high abundance of organisms, either squid or fishes were found below the lift net that equipped with αr23,3° and αr32,6o reflector. Descriptively the squids that were hauled by αr23,3° reflectored light bulb lift net weighing 5.774 kg. In comparison the αr32,6o reflectored light bulb lift net resulted 4.977 kg, as for the standard covered light bulb only resulted 3.180 kg of squids. As a contrast the catch result of the fish types that were hauled by αr32,6° reflectored light resulted 2.010,8 kg, followed by αr23,3° reflectored light (1.692 kg) and covered light (1.257 kg). The weight of the total catch showed that the use of a covered lamp influenced the weight of the caught squids and fish kinds. However, statistic test showed difference where the covered light bulb has more influenced on the fish kinds with Pvalue <0.05 or 0.00. Meanwhile the squid catch result that was operated with the covered light bulb did not show real difference (Pvalue >0.05/0.49). Furthermore, the interval time of the catch operation resulted the largest catch on both organism types happened after the midnight, resulted 12.661 kg of squids and 3.019 of fishes. The catch operation that was conducted before midnight only resulted 1.270 kg of squids and 1.940,5 of fishes. Statistic result showed that time interval influencing the catch result that was hauled by lift net Pvalue <0.05. | en |
