Quantification of the size effect of recreational fishing prohibition on stock enhancement of resident stream salmonids

This study estimated the size effect of recreational fishing prohibition on stock enhancement of resident stream salmonids. Data on environmental conditions and fish populations were collected in fishing-prohibited and-permitted areas in several tributaries with diverse environmental conditions. The average treatment effect of the fishing prohibition on the population density was estimated with the adjustment of environmental conditions by inverse probability weighting estimation using propensity scores. Fishing prohibition significantly increased the population densities of mature fish by an average of 2.18 times, but not those of immature fish.