Seasonal changes in fishes ascending a paddy field ditch in the Naka River system, central Japan.

概要

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Seasonal changes in the number and maturity of fishes ascending the Ogawa paddy field ditch in the Naka River system, Tochigi Prefecture, central Japan, were recorded from April to October in 1999 and from April to September in 2000. Totals of 949 fishes, representing 17 species and 745 fishes (12 species) were trapped in 1999 and 2000, respectively. Gnathopogon elongatus elongatus, Misgurnus anguillicaudatus and Pseudobagrus tokiensis were dominant in both years. Most individuals of G. elongatus elongatus, Cobitis biwae and Rhinogobius sp.OR were caught from late Spring (April) to early summer (June), most being mature. Pseudobagrus tokiensis, Silurus asotus and Zacco platypus were caught in summer (June-August), most also being mature. Zacco temminckii and Tribolodon hakonensis (mostly juveniles) were caught in summer and autumn (July-October). Mature and juvenile Misgurnus anguillicaudatus were caught throughout the study period (April-October). The results indicated varying periods and purposes for ditch ascent among the species, the ditches clearly being important in maintaining the biodiversity of freshwater fishes in paddy fields.
日本魚類学会の論文