Judul: Reflector Utilization with Different Angles: An Effort to Increase Fish Catch on Lift Net in Kao Bay, North Halmahera
Abstrak: 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
Keyword: Light, reflectors, fish, squid