Temporal Changes in Infection by Myxobolus nagaraensis in Rhinogobius (Gobiidae) in the Nagara River Basin, Central Japan, from the 1960s to the 2020s

species parasitism in the main stream from 2007 to the present, suggesting that parasitism may have predominantly spread to tributaries after 2007. Reasons for the changes in parasitism rates over time were discussed, including the possibility that parasitism rates in the main stream may have been underestimated due to biases caused by the sampling methods.