養鰻池における憩場の形式とその効果

概要

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Since the previous report in 19531), the use of the resting pool in eel-pond has become popular, and almost all the ell-ponds in Kawashiri district (Fig. 1) are now equipped with it. The 86 eel-ponds at the district out of 204 were observed as to the size, area, water supply and utilization of vertical pump and agitator. For the 12 resting pools of different types selected, studies were made on diurnal change of water temperature, disolved oxygen, NH4-N etc. Results are summerized as follows: 1. The resting pools are generally 40-70cm in depth and take increasingly a form of rectangle and are supplied with well water mixed from creek (Table 1). 2. The resting pools measure 50-60m2 in surface area or about 1.3% to 4, 500m2 of the rearing ponds. 3. The resting pools may be divided into 3 types by their water circulation: the running water type (Fig. 2), semi-circular type (Fig. 3) and circular type (Fig. 4). 4. During summer time, the water of creek or well supplied 40-70l/sec. in the pools at night, kept the temperature of pool water 4-6°C lower and the disolved oxygen 0.9-3.8 cc/l higher than those of the rearing pond. 5. There are no apparent trouble or difficulty in keeping 3.2-12tons of eel in a resting pool of 50-60m2 at night which is supplied with above mentioned amounts of water and it saves safely the eel from their "gulping".
社団法人日本水産学会の論文