Publication Date:
2021-05-19
Description:
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.
Description:
Iranian Fisheries Science Research Institute
Description:
Published
Keywords:
Fishing method
;
Set net
;
Selective fishing
;
Iranian Caspian coastal area
;
Fishing cooperative
;
Species
Repository Name:
AquaDocs
Type:
Report
,
Refereed
Format:
118pp.
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