1991 Fiscal Year Final Research Report Summary
Behavioral Physiology of Fish in Capturing Process of Mid-Water Trawl
| Project/Area Number |
01460233
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
General fisheries
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| Research Institution | Tokyo University of Fisheries |
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Principal Investigator |
ARIMOTO Takafumi Tokyo University of Fisheries, Professor, 海洋生産学科, 教授 (20106751)
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| Co-Investigator(Kenkyū-buntansha) |
SHIRAI Takaaki Tokyo University of Fisheries, Associate Professor, 食品生産学科, 助手 (90206269)
FUKUDA Hideo Tokyo University of Fisheries, Associate Professor, 資源育成学科, 助教授 (60199239)
OKAMOTO Nobuaki Tokyo University of Fisheries, Associate Professor, 資源育成学科, 助教授 (40114912)
INADA Hiroshi Tokyo University of Fisheries, Associate Professor, 海洋生産学科, 助手 (90176397)
SAITOH Kiyotaka Tokyo University of Fisheries, Associate Professor, 海洋生産学科, 助手 (30111686)
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| Project Period (FY) |
1989 – 1991
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| Keywords | Mid-water trawl / Capturing process / Walleye pollock / Visual physiology / Swimming behaviour / Fishing Gear designing / Electrophysiology / Telemetry |
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| Research Abstract |
The research project deals with the behavioral physiology of target species in relation ot the gear geometry in the capturing process of mid-water trawl fishing, consisted of three main themes ; the analysis of gear geometry and control, the reaction of targeted fish towards the gear, as well as the visual physiology and the swimming physiology of walleye pollock, Theragra chalcogramma.
On board the northern off-shore trawlers, the acoustic telemetry observation was conducted to understand the static and dynamic geometry or net gear ; such as the depth, height and width of net mouth and the otterdoors distance. These factors of net shape during towing were corresponded to the Lowing speed and warp length. From the acoustic results, the deck working cycle for the net shooting and hauling procedures was analyzed and discussed.
Concerning the visual physiology of walleye polloock, on-board sampling of eyeball was conducted for the purpose to identify the retina adaptation in relation to the
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towing depth and time of day. The microscopic examination-snowed that the retina was not fully light-adapted Pven with the daytime sampling in the fishing ground of 200m or deeper. It indicates the incapability of colour discrimination but the higher sensitivity to the weak light intensity. Besides, with the data of lens size arid visual cell density on the retina, the visual acuity was determined so as to estimate the maximum sighting distance accordinig to the size of fish in the ideal condition. T. n order to determine Lhe light sedsitivity of walleye pollock, the electrophysiological experiments were also conducted with the variation of the wave-length, durationl/frequencies and intensity of light, stimuli, in comparison between light and dark adaptation of retina under the various lighting conditions.
Another important factor of behavioral physiology is the swimming performance of fish as the muscle activity in relation to the reaction of fish toward the towed gear. On-board and laboratory experiments was conducted to measure the muscle contraction time from the view point of the scale and temperature effect. From the results, the maximum tail beat frequency was determined. In addition, the swimming behaviour in tank was video-recorded to obtain the data for the stride length per I tail beat. As the final, the maximum swimming speed was estimated with the special reference of the temperature dependence. The results of temperature effect on muscle contraction time indicate better swimming performance of fish at higher temperatures. This implies that a relatively higher towing speed is required in mid-water trawling in which water temperature is relatively high. Less
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Research Products
(8 results)
