圖書典藏及影音數位平台

石岡壩魚道，於921地震復建時，於右岸壩體受損之16號溢洪道所增設，90年12月11日完工。設計水流量0.3立方公尺，其入口(出水口)標高259.57公尺、出口(進水口)標高269.40公尺、總長147公尺，屬於水池階段式(Pool and Step or Pool and Weir Type)，係供洄游生物使用。 歷年(截至2021年)石岡壩魚道及其上下游之測站中，記錄14科47種魚類，甲殼類3科9種。生態調查結果顯示此河段的環境污染低且生物資源相當豐富。而歷年監測可說明石岡壩魚道的效果良好，本區的水域生態還是維持在相當好的程度，且上下游之間都有非常豐富的河川生物資源。 因此，本計畫工作項目包括：(ㄧ)長庚橋至埤豐橋（含魚道）水域生態及洄游生物監測調查、(二)建立石岡壩魚道及其上下游水域生物物種名錄、(三)探討石岡壩魚道及其上下游之水理及水質與水域生物分布關係、(四) 辦理環境教育推廣活動、(五)綜整歷年生態資料與統計分析、(六)評估石岡壩下游在建工程及完工後對於陸域、水域生態及生態關注區域的生態環境及其變動及有關生態保育措施、(七)工作報告及成果報告編撰印製等。

The purpose of this project is to conduct an aquatic ecological resource mon itoring survey to understand the ecological resources of the fish passage and its upstream and downstream areas, as well as the biological utilization status of the fish passage facilities at the Shigang Dam. The ecological monitoring of fishway and the upper and lower reaches of Shihgang Dam was complied on Febuary 27-March 1, June 17-20, August 20-21, and November 6-7, and two additional inves tigations of Shihgang Dam fishway were complied on May 1 and September 18. The fishway discharge become less in August and September due to the construc tion work. The outlet of fishway is clogged after the typhoon ,so there was almost no water and lots of dried fish in the fishway in November. A total of 3,580 fishes in 8 orders, 13 families, 36 species; 289 crustaceans in 1 order, 3 families and 4 species; 4,189 aquatic insects in 6 orders, 24 families; and none of zooplankton were recorded in Shihgang Dam fishway and the upper and lower reaches stations. A total of 1,579 fish in 7 orders, 10 families, 28 species and 126 crustaceans in 1 order, 3 families, 3 species were recorded in the six surveys in the fishway. In the other way, a total of 1,262 fish in 4 orders, 6 families, 19 species and 34 crusta ceans in 1 order, 2 families, 2 species were recorded in the new constructed energy dissipator fishway in November.Comparing the fish survey results of this year with previous years, several new species have been recorded, including Pterygoplichthys pardalis, Poecilia reticulata, Coptodon zillii and Geophagus brasiliensis. In addition, some recorded species were found at new location, Anguilla marmorata, Carassius auratus ssp. and Channa striata atChang Geng Bridge, Distoechodon compressus and Channa striata at the auxiliary dam , and Coptodon zillii and Channa striata at the Pifeng bridge included. Although the underwater photography method may overestimate the number of some fish due to repeated counting and underestimate some swim ming fish when the water quality is turbid, the capture rate of benthic fish is higher than that of the electrofinshing method, and The feeding behavior of certain fish species can be recorded. So, it can still be used as supplementary data for fish passage surveys. Data over the years show that maintaining smooth water flow in fish passages can help stabilize the population of Sinogastromyzon puliensis. In the other hand, the invasion of Onychostoma alticorpus and Distoechodon com pressus is more serious in the downstream of Shigang Dam than that in the upstream. In the future, if the jet flow problem at the outlet of fishway is solved, it is recommended to regularly set up traps in the fishway or use electrofishing method to remove alien species to prevent the continued spread of their population. It is suggested that the removal operations at fishway being cattied out in June to September, considering the duration of the seasonal migration of the invasive spe cies such as Distoechodon compressus and Spinibarbus hollandi. This year, Channa striata, which is a ferocious invasive species, have been recorded at both upstream and downstream monitoring stations of the Shigang Dam. Since this species poses a significant threat to native organisms, it is recommended that fu ture monitoring and removal efforts be strengthened. During the fourth survey this year, the engineering team implemented relevant ecological conservation measures. This year, three sessions of environmental education promotion activi ties were held at Shigang Elementary School, Dongshi Elementary School and Shigang Dam Management Center on October 24 and 25. The overall results of the courses were good and were widely welcomed by teachers, students and vol unteers. It is hoped that the jet flow problem at the outlet of the Shigang Dam fishway which still affects the upward movement of fish eould be solved after the trash rack renovation.