Abstract:
This survey study was periodically conducted in July, 6 times every year. There were 3 periods: 1st period (2002); 2nd period (2008) and 3rd period (2014). It sheds light on the impact of forest and peat land exploitation on decreasing biodiversity of fishes in Rangau River, Riau-Indonesia. Using some catching tools such as landing net, fishing trap, fishnet stocking and fishing rod. The sampling activity was administered at eight stations which were conducted by applying “catch per unit effort technique” in primary time: 19.30-07.30, for 3 repetitions for each fish net measurement within 30 minutes at every station, at position or continuously casting. The sampled fish were selected which were relatively in minor size but had represent their features and species. The fish were labelled and were preserved with 40% formalin. The determination and identification of fish were conducted at laboratory. Secondary data was collected by mean of interviewing the local fishermen about the surrounding environment condition of Rangau river. Data analysis consisted of biodiversity data, biodiversity index and fish existence frequency. The finding in 1st period, in 2002, total caught fish were 60 species: 36 genera and 17 families. In 2nd period in 2008, total caught fish were 38 species which consist of 30 genera and 16 families. In 3rd period, in 2014, there were 23 of fish species were found comprising 17 genera, 12 families. The highest biodiversity index (H1) through out the survey was in VIII stations, in period 1, 2 and 3 with (H1) 1.99; 1.85 and 1.80. On other hand, (H1) the lowest biodiversity index (H1) in 1st period was at IV station (0.95). In 2nd period, there were no fish identified at station-III ( H I = 0 ) and in 3rd period, there were no fish at station II, III and VII. In 1st period, there were 4 commercial value fish were found. In 2nd period, there were 2 species were found in 3rd period, there was only 1 commercial value fish species were caught. The fish highest existence frequency was Cyprinidae family. The second highest was the fish group of Siluridae and Bagridae family. Conclusion, impact of forest and peat land exploitation towards the decreasing biodiversity of fishes in Rangau River.
