碩士 / 國立高雄海洋科技大學 / 漁業生產與管理研究所 / 102 / Abstract
According to the statistics released by Fisheries Agency in year 2012,
the total catch quantity of large scale purse seiner vessel was 199,322
metric tons, which occupied 29% of total catch capacity of entire pelagic
fishery productivity. The vessel number was 34, which has made Taiwan
the largest purse seiner fleet country in the western and central Pacific
Ocean.
In the process of retrieving fishing net of the purse seiner operation,
the net mouth is always drifted back by the current, leaving the net
unable to close completely so that part of fish school will escape from the
gap of the net. The purpose of this research is to improve the net
efficiency by utilizing the settlement plate to deepen the depth of the net
mouth, to strengthen the fishing efficiency of the purse seine set.
The settlement plate of this research is based on water wing theory.
The triangle settlement plate is made of plastic board in three different
dimension(11cm, 13cm,15cm) and the plate is attached to the bottom of
the net mouth with three different attacking angles(30 degree, 40 degree,
50 degree). The experiment was carried out in the experimental water
tank under various current speed and the net deviation angle and net
depth data was recorded and analyzed.
The results revealed that:
1. Under any circumstances in which experiments were conducted, when
the net attached with settlement plates and sinkers, the deviation angle
of the net increased upon increasing of current speed, and the net
depth decreased when the current became stronger.
2. When the net attached with sinkers (46.8g、70.2g、93.6g) except the
23.4g one, it was found that there was significant discrepancy in
comparison with the conventional mode net without sinkers upon T
test , proof of effectiveness of decreasing net mouth deviation. The
net depth also increased with all sinkers. However, there is great
concern of net broken caused by net tension if the sinker is too heavy.
3. It was very effective for net mouth stabilization when the 11cm
settlement plate with 50 degree attacking angle was applied to the
net .The 13cm and 15 cm settlement plates with 40 and 50 attacking
angle were also greatly effective to stabilize the net mouth.
4. When T test was conducted between conventional net mouth attached
with 11cm/13cm/15cm settlement plates and the one without
settlement plates, it was found that there was discrepancies on net
mouth deviation angle. The net depth improved as well when the
attacking angle was 40 degree or higher.
5. When comparing the conventional net mouth attached with settlement
plates and the one with sinkers, the one with settlement plates had
better effectiveness than the one with sinkers in terms of net mouth
deviation. As to the net depth, the net mouth with sinkers had better
effectiveness than the one with settlement plates. However, it must be
taken into consideration by the ship owners as there is great concern
of net broken caused by net tension if the sinker is too heavy.
| Identifer | oai:union.ndltd.org:TW/102NKIM0451013 |
| Date | January 2014 |
| Creators | Lin Cheuan-cherng, 林綣城 |
| Contributors | Yu Kei-chien, Wu Chin-chen, 俞克儉, 吳金鎮 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 82 |
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