The Fluctuation and Distribution of the Population Density and Fish Movement of Rose Bitterling in Shin Tone River

Abstract

From the analysis of fish catch data and mark-recapture experiments the population density and movement of rose bitterling Rhodeus ocellatus ocellatus was determined. The mean of the catch per trap was considered as the index of the population density.
It was found that the population density was high in summer and very low in winter with a peak in late summer.
In the daily mark-recapture experiments using Neutral Red and Bismark Brown solution, about 90% of the recapture numbers in every month were found within 30-40m from the released points. A very few of the fish managed to cover a distance of 100m. In other mark-recapture experiments using fluorescent pigment, in a five month period more than 90% of the recaptures were made near their point of release, having covered only a distance of 200-700m. From these, it was concluded that only limited and localized fish movement occurred during the daily or the five month interval of the experimental period.
Fish abundance estimates based on the daily mark-recapture date of each month using the Petersen method were calculated as 13, 000-35, 300 fish for a 36m river shoreline for August and September when the fish catch was highest.