Author : Wahyu Andy Nugraha

Summary : Investigations on the possibility of using clove oil as alternative for cyanide in fishing was tested by recording the stunning and recovery times of grouper Epinephelus fuscoguttatus, and measuring the bleaching percentage and change in zooxanthellae density in Porites lutea relative to 10 g/L cyanide, which is normally used in cyanide fishing. The average stunning time of grouper E. fuscoguttatus decreased exponentially while its average recovery time progressively increased with increasing concentrations of clove oil. At 30 g/L, clove oil had a similar stunning effect with cyanide. Exposure duration to clove oil significantly affected recovery time of grouper; all small fishes exposed up to 30 min to these substances recovered, but none survived after exposure for 60 min. Bleaching percentage and zooxanthellae density of P. lutea exposed to 30 g/L clove oil were significantly affected by exposure time and concentration. Coral exposed for 10 min almost had a constant bleached area which increased with longer exposure time. Moreover, the bleached area of P. lutea that was sprayed once did not differ from an untreated coral, but this was significantly lower compared to treatments with multiple applications of the substance. And, zooxanthellae density rapidly decreased when exposed over a longer time or to higher doses of clove oil.