ALBERT

Beschreibung: This research project is conducted to develop a protocol on designing and manufacturing a set net by mathematical process. It was expected to achieve an appropriate model development for economical fishing. It is also aimed to function a substitute for the type of fishing gears that are not economical and some fishing tools exert pressure environmentally in the fishing area. The experiments took place from Iranian coastal area from Astara until Torkaman region. In this research study ecological, biological including topographical status are considered. The fish biomasses, length frequency, species composition in the catch have been identified. Biometric data of economical species, time of migration and its courses, the distance of fish shoal relative to shoreline are recorded. Bottom quality of seabed and gradient of coastal area, estuary, and bays have been determined. Distribution of depth area, which traps could be set has been mapped. Water transparency, wind direction, water velocity, wave height are measured. Meteorological data of the near past years are collected. The level of bony fishes catch and its diversity in beach seines are also gathered. The field research in Southern parts of Caspian Sea, the mathematical process and analyses of data using state of the art methodology contributed to design and develop an appropriate model for fabrication of a set net with good results and practicality. In this the experience of coastal fishing by set nets in Azerbayjan Republic, Black Sea, and other lakes and reservoir being incorporated in our designing and fabricating. The research revealed the present manufactured model set net could be applied in coastal area of Caspian at the depth limits of 20 meters; Anzaly coastal lagoon and parts of Gorgan bay are excluded. In south west of Caspian from Astara-Talesh which beach seining could not be economically operated, this type of set net regarded as viable alternative. It is also the preferential area for this type of set net application could be named as river,s estuaries, and on the beach seine site facing sea-bed erosion and destruction, which the new developed model are workable substitute. Scouring qualified references and textbooks indicate the best type of set net, in view of physical skeleton (hard, soft, combined formed) structure, also considering water depth, solidity and needed firmness of net and economical and selective fishing, the traps part mainly should be set on soft structure on buoyant. This initiative enable the set net could be move in seaward depth, despite higher water currents and more elevated wave. In this circumstances the set net display more firmness in contrast of variation of its shape and destruction when operating. Set nets with soft structure and its bag parts (bag less, two bag, one side bag and a longer bag linear), with longer bag linear which are costly effective in fabricating, easy setting and lifting from sea, damaging limitation in contrast to waves, better fishing capability and emptying fish could be used more efficiently by beach seines cooperative by fishers of 8 or 10. With regard to the width of fish shoal in Iranian coastal area, it is suggested the traps could be joined with additional leader and a second trap at the end of leader being attached. In this condition relative to distance of migrating fish school, the length of walls of should not exceed from 400 500 m. Evaluation of the selection characteristics in set nets regarding selectivity on fishing in different phase, it is possible to capture of target species more sustainable by changing nets mesh in body parts skeleton and walls including traps by increment of mesh size option.

Beschreibung: Iranian Fisheries Science Research Institute

Beschreibung: Published