タイ国チャオプラヤー河最下流域における外来・在来淡水魚の利用形態とその経済的価値

抄録

 We conducted semi-structured interviews at 44 local markets in the lowermost Chao Phraya River basin, Thailand, to examine: (1) species composition, (2) economic importance, and (3) the utilization of native and non-native freshwater fishes sold by local vendors. Four geographical regions were sampled: Rangsit Area, East Coastal Zone, West Bank, and West Coastal Zone. We recorded a total of 19 families, 33 genera and 43 species of fish (70% native and 30% non-native). The species sold in local markets, and their diversity, did not differ greatly between regions. Most fish sold in the markets were imported from other provinces in central Thailand, while locally caught/produced fish were rare. Non-native species had higher economic value and larger sales volumes than native species, indicating that non-native fishes currently form the major food source for local inhabitants. These findings indicate that non-native fishes provide ecosystem services as members of the lowermost Chao Phraya River Basin ecosystem, but they also suggest that such services may include disservices, depending on the species and areal/temporal contexts. Therefore, management of non-native fishes should involve a species- and site-specific approach from multiple perspectives. We need a better understanding of the interrelationships between people and non-native fishes to promote more efficient management of ecosystems in the lowermost Chao Phraya River Basin.