海域における養魚場の海水交流に関する研究 (1)　網仕切り式養魚場の海水交流

The present work deals with the exchange of sea water in the Megishima and Ieshima fish farms. The tidal currents measured by the current meter and current drags in the Megishima fish farm are shown in Figs. 2 and 3. The current velocity in this fish farm was only a quater of the outside of it because of being decreased by the net and embankment resistances (Fig. 5). The volume of exchanged water calculated from the current velocity during one tide is given as in Table 2. It is about ten times as large as the volume of fish farm at low water. The water qualities at high and low water are shown in Tables 3 and 4. The turbidity and COD values within the fish farm were larger than those of neighborhood. This was considered to be due to the bottom mud stirred up by the strong current of neighborhood owing to shallow depth of the fish farm. But the dissolved oxygen did not indicate any decreasing despite of the increment of turbidity and COD values, because the volume of water exchanged by tidal current in this farm was very large. The qualities of bottom mud are shown in Table 5. The ignition loss, sulfide amounts and oxygen consumption of mud in this fish farm were also larger than those obtained from the outside of it. It is feared that the dissolved oxygen of sea water will decrease, if the polluted substances of bottom mud increase beyond the present level. The tidal currents measured by the current meter and current drags in the Ieshima fish farm are shown in Figs. 9 and 10. The current in this fish farm showed decrease in velocity by the resistance from the net, and the velocity was about a half of that in the outside of it (Fig. 11). The volume of exchanged water in one tide as shown in Table 9 is about one point three times as large as the volume of this fish farm at low water. The water qualities at high and low water are shown in Tables 10 and 11. The turbidity and COD values at Sts. 6, 9 and 10 were larger than those of the other stations. The high values at St. 6 were considered to be derived from the dissolved substances in food and from the shortage of exchanged water, but the causes of their distinct values seen at Sts. 9 and 10 were unknown. The qualities of bottom mud are shown in Table 12. The sulfide amounts and oxygen consumption of mud at Sts. 3 and 6 were larger than the other stations. This was considered to be caused by the submerged food from St. 6. In conclusion, the bottom mud of the present fish farm expect St. 6 is comparatively clean, but it may be suggested that the polluted substances in bottom mud will be accumulated and their distribution will be broadly extended with years owing to the incomplete exchange of sea water.

言語

bibliographic_information

ja : 内海区水産研究所研究報告
en : Bulletin of Naikai Regional Fisheries Research Laboratory

巻 23, p. 1-20, ページ数 20, 発行日 1966-03

出版者

内海区水産研究所

言語

出版者

Naikai Regional Fisheries Research Laboratory

言語

item_10002_source_id_9

収録物識別子タイプ

PISSN

収録物識別子

0497-5022

item_10002_source_id_11

収録物識別子タイプ

NCID

収録物識別子

AN00176718

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識別子タイプ

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