Study of the relationship between Anguilla japonica resource and habitat destruction by satellite remote sensing in the past 40 years
2013
Hochschulschrift
Zugriff:
101
The Japanese eel is an important aquaculture species in Japan, Korea, Taiwan and China. At present the only source of glass eels needed by fish farmers comes solely from the catches made by fishermen at river mouths. However eel stocks have been in rapid decline since the 1970s. Furthermore with urbanization and constant expansion of industrialization in various countries, the natural habitat of eels have been severely damaged. The aim of this study is to discuss the relationship between habitat changes in the four East Asian countries and the long-term eel stock size from the 1970s to the early 2010s. The method of this study is using satellite remote sensing on land cover change (LCC). Satellite remote sensing is an efficient tool for analyzing temporal and spatial changes as it could record geographical features on a large geographical scales over times to enhance efficiency and accuracy to facilitate data analysis. Present study focus on four major eel-catching rivers in each of the four East Asian countries. Then satellite images of those rivers were downloaded from the USGS website and fed to ArcGIS to analyze the condition of habitat change in each of them. The result of this study shows that in the period of 1970s~2010s in Japan, the length of natural habitats in the rivers decreased by 21%, loss of natural areas is 27%, and the habitat quality index, (HQI) decreased by 6%. In Korea, the length of natural habitats in the rivers decreased by 46%, the loss of natural areas is 57%, and the HQI decreased by 29%. In Taiwan, the length of natural habitats in the rivers decreased by 22%, the loss of natural areas is 53%, and the HQI decreased by 50%. In China, the length of natural habitats in the rivers decreased by 76%, the loss of natural areas is 81%, and the HQI decreased by 25%. In terms of long-term glass eel stock sizes, Japanese official data shows 80.6 tons of annual production in the 1970s, 35.9 tons in the 1990s and in the recent 5 years it is 6.6 tons. The eel stock size decreases by 92% from the 1970s to the present day. According to local fisherman in Fulung, eel stock data in the period of 1984~1995, the mean annual catch of glass eels is 334096, however, in the period of 2007~2013, the total number of glass eels is 14190 on average per year and the stock size decreases by 96% from the 1970s to the present day. In summary, in East Asia from the 1970s to the 2010s, the total length of natural habitats decreased by 47%, the loss of total natural habitats is 81%, and the HQI decreased by 25%. Compared with the official eel stock decrease of 92% in Japan, and local fisherman data of a decrease of 96% in Fulung, this shows eel stock size decline should be related to habitat loss.
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Study of the relationship between Anguilla japonica resource and habitat destruction by satellite remote sensing in the past 40 years
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Autor/in / Beteiligte Person: | Chen, Jian-Ze ; 陳健澤 |
Link: | |
Veröffentlichung: | 2013 |
Medientyp: | Hochschulschrift |
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