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http://ntour.ntou.edu.tw:8080/handle/987654321/44272
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Comparison of two uropod-cutting methods for tagging of juvenile grass prawn Penaeus monodon
http://ntour.ntou.edu.tw:8080/handle/987654321/46039
title: Comparison of two uropod-cutting methods for tagging of juvenile grass prawn Penaeus monodon abstract: Abstract:
Two uropod-cutting methods were used and compared for tagging of Penaeus monodon juveniles: LE-cutting half of the left exopod; and WR-cutting the whole right uropods. The treatments were composed of LE, WR, Control (with uncut uropods), and Mixed (equal numbers [5 prawns] of LE, WR and Control in one tank). Fifteen prawns were used for each treatment and the Control, with two replicate tanks for each. Results show that there was no significant difference (P>0.05) on growth and survival among the experimental treatments and the Control after three months of culture. Regeneration of uropods commenced within a week of culture and complete regeneration was evident after one month in LE treatment and after two months in WR treatment. Abnormalities observed in regenerated uropods for LE treatment were composed mostly of hollow type (HT; 65.2%) and flat type (FT; 25.8%). Tag retention rate was 91.0%. In WR treatment, 80.3% regenerated into normal type (N) composed of those with normal pigmentation (33.9%) and with less pigmentation or discoloration (46.4%). Other abnormality observed was incomplete growth (IG; 7.2%) while the rest (10.5%) cannot be classified due to the presence of severe tail rot. Tag retention rate for this cutting method was only 53.3%. In the Mixed treatment, prawns tagged using LE were easily distinguishable from the rest of the prawns (Control and WR) in the same tank. A mean of 73.3% of the LE cut prawns regenerated into HT and 6.7% into FT. For prawns with WR cut uropods, only 40% regenerated into N with discoloration, while the rest (~60%) either regenerated into N which is indistinguishable from the Control, or not classified due to tail rot. Overall, LE method is recommended for tagging juvenile P. monodon as it can produce more distinguishable abnormality in the regenerated uropods compared to WR method. The abnormalities observed can be retained by the tagged prawns even after several molting cycles during their growth.
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Impact of externality on the optimal production of eel (Anguilla japonica) aquaculture in Taiwan
http://ntour.ntou.edu.tw:8080/handle/987654321/46037
title: Impact of externality on the optimal production of eel (Anguilla japonica) aquaculture in Taiwan abstract: Abstract:
This paper aims to profile the potential externality in Taiwanese eel aquaculture. It provides a model to incorporate the negative
environmental impact from the eel aquaculture industry. It also answers what the optimal output levels and prices of the Taiwanese
eel aquaculture industry should be. Our simulations suggest that the optimal production for Taiwanese eel industry will decrease by
5.71% (9.10%) from the baseline for the period 2001–2005, when the cost of groundwater use (pollution prevention) is
internalized. If the costs of groundwater use and water pollution are included, eel production further drops by 14.95%. The optimal
prices, regardless of the retail or farm price, are driven up because of the environmental concerns.
© 2006 Elsevier B.V. All rights reserved.
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Cobia aquaculture in Taiwan
http://ntour.ntou.edu.tw:8080/handle/987654321/46035
title: Cobia aquaculture in Taiwan
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Development of an intelligent feeding controller for indoor intensive culturing of eel
http://ntour.ntou.edu.tw:8080/handle/987654321/46028
title: Development of an intelligent feeding controller for indoor intensive culturing of eel abstract: Abstract:
The cost of feed is usually the greatest operating cost in aquaculture. Over feeding results in left over feed, which leads to not only the extra-cost, but also poor water quality, stress to the fish and an extra-load on the mechanical filters, biofilters and oxygenation equipment. Feeding management is as important as the design of the diet itself and knowing when to stop feeding is of great importance for successful feed management. Timer-controlled automatic feeders with a rotating plate and scrubber are widely used in the indoor re-circulating eel culturing industry in Taiwan. The device was designed to run at preset times for a preset duration with no other control. An intelligent feedback control system was developed. The gathering behavior of eels was observed by an infrared photoelectric sensor and converted to digital signals. The feeder equipped with such a sensor and governing control strategy is able to stop feeding according to the gathering behavior of eels. The control strategy contains six user-adjustable parameters with default values. If the sensor fails to detect the gathering behavior for three (default) consecutive trials, the feeder will stop feeding until the next wake-up, thus reducing the risk of polluting the water, etc.
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