EŠect of newly established import quarantine regulations on the supply of alien palaemonid shrimp Palaemon sinensis in Japan

Abstract

The species composition of palaemonid live bait shrimp, the target aquatic animal of a newly established import quarantine regulation, was investigated in fishing bait shops in Kanagawa, Aichi, Osaka, and Hiroshima Prefectures, Japan from May 2016 to May 2017. Palaemon sinensis, an alien species in Japan, imported from China comprised 83%93% of the total shrimp sold by bait shops in each prefecture before establishment of the regulation in May 2016. After the regulation was established in July 2016, Palaemon paucidens, a native species of Japan, comprised 83%100% of the total shrimp sold in each prefecture, indicating that the supply of palaemonid bait shrimp changed drastically from imported sources to domestic sources. However, P. sinensis comprised 9% of the total catch sold in Aichi Prefecture inMay 2017 and from 5%11% in Hiroshima Prefecture from November 2016 to May 2017. These results suggest that P. sinensis has already been introduced into domestic harvest areas, such as Okayama Prefecture, and has been supplied as fishing bait.