水産養殖研究開発ジャーナル

概要

Fish Cage Site Selection at Kibuyuni in Kwale County, Kenya : Tidal variations, Waves Height, Current Speed and Direction Status

Athman SH, Hole GM*, Magori C, Ndirangu S, Zamu MS

The objective of the study was to select a suitable site for cage fish farming in the South Coast of Kenya at Kibuyuni, by investigating the status of tidal variation, wave height, and current speed and direction, which was done using the Acoustic Wave and Current Profiler (AWAC). The AWAC was deployed at 13.6 m depth; the study showed that the current speed of Kibuyuni was varying from the surface to the seabed; surface water 0.8690 m/s, 6 m depth 0.6090 m/s, 8.5 m depth 0.5590 m/s, respectively. According to Norwegian fish cage site classification, current speed should not exceed 1.5 m/s because this can cause the cage to move if not well fitted with heavy weights. Therefore these current speeds indicate that the area is suitable for cage installation. The highest tide was 13.5680 m while the lowest was 9.6840 m. The tidal fluctuation/difference is 3.8840 m which is good for adequate water exchange that will enable the flow of nutrients through the cage. The significant wave height (Hs) recorded was 0.36 m. Note: (Maximum wave height=Hs × 1.9). Therefore the theoretical maximum wave height= 0.36 × 1.9=0.684 m. According to Norwegian fish cage site classification, maximum wave height should range between 0.5-1.0 m for a considerable moderate for fish cage site. Therefore this site is considered moderate for fish cage.