Impact of the Great East Japan Earthquake on Reproductive Biology of the Freshwater Teleost Bluegill Lepomis macrochirus

Abstract

Soon after the Great East Japan Earthquake and the subsequent accident at the Fukushima Daiichi nuclear power plant, we studied the reproductive biology of freshwater teleost bluegill (Lepomis macrochirus) in a pond in the city of Iwaki, Fukushima Prefecture, about 50 km south of the nuclear power plant. The breeding period of the bluegill was abbreviated and the frequency of spawning decreased. The radiation air dose rate and level of radioactivity in the fish were less than would be expected to trigger behavioural alterations or to suppress reproduction. The occurrence of aftershocks and two episodes of torrential rain is the likely reason for changes in the reproductive behaviour of bluegill in the pond. These results suggest that our observations can be explained by a combination of natural disasters, rather than the effects of nuclear radiation.

Male guarding behavior and brood predators of invasive Bluegill in a Japanese lake

“…Due to these impacts, the Bluegill is listed among Japan's 100 worst invasive species (one of the eight listed fish species; Ecological Society of Japan 2002) and is controlled through culling and removal (Yonekura et al 2007;Fujimoto et al 2010). Spawning of Bluegill has been reported in a host of lentic systems within Japan, and successful spawning is thought to enable their continued spread and establishment in areas where they have been introduced (Nakao et al 2006a;Kitano 2007;Shiah 2012, 2013;Iwata et al 2014). The removal of guarding males from nests is thought to be an effective method for reducing Bluegill population size and is often used in Japan (Yamaguchi 2005;Yonekura 2008;Egawa et al 2014).…”

“…2006a; Kitano 2007; Yamamoto and Shiah 2012, 2013; Iwata et al. 2014). The removal of guarding males from nests is thought to be an effective method for reducing Bluegill population size and is often used in Japan (Yamaguchi 2005; Yonekura 2008; Egawa et al.…”