|| 要旨トップ | 目次 |||日本生態学会第65回全国大会 (2018年3月、札幌) 講演要旨
一般講演（口頭発表） C01-12 （Oral presentation）
An important issue in the management of stream salmonid fisheries in Japan is the extent to which catch and release (C&R) regulations can be used to sustain a quality recreational fishery without the need for supplemental stocking. We examined this issue in the Itoshiro River, Gifu Prefecture, central Japan where a catch and release (C&R) regulation for salmonids, particularly white-spotted charr, Salvelinus leucomaenis, was adopted in 2000, and stocking was discontinued in 2002. We compared fish populations under two treatments: sites that were C&R fishing only and sites where harvest was allowed under general fishing regulations. Fish were not stocked in the C&R sites but were stocked in the general regulation sites every year where anglers could keep fish >15 cm with no daily creel limit. We electrofished and estimated the charr populations across the treatments and found a total of 483 individuals of charr from 30 sites during 2014-2017. A significantly greater fish density was found in C&R sites (an average of 515g fish per 100 m^2) compared to the sites with the general fishing regulation (162g per 100 m^2). Moreover, fish >15 cm in fork length comprised nearly 50% of the population in the C&R sites but only 28% in the general regulation sites. These results suggest that a C&R regulation can be used to maintain a quality recreational fishery without the need to stock hatchery charr.