Abstract
The spatial distribution and ecological status of the golden mussel, Limnoperna fortunei, in Lake Kasumigaura, Ibaraki Prefecture, Japan, were investigated from June to September, 2006. The mussel was found along half of the Kasumigaura lakefront, from the western to the southern coast. The mussels were attached to hard substrata, such as concrete walls and stones. Most of the mussels were collected from the underside of stones on the lake bottom. The highest density sites of the mussel are in Ami-cho, on the western shore of the lake, where one researcher was able to collect a maximum of 154 individuals in 10 minutes. No mussels were found in the northern and eastern parts of the lake. We could identify two cohorts of the mussel by size-frequency distribution in August and September, 2006. The largest individual among collected specimens was 31.4mm in shelllength. Based on this maximal size and a previous report, the first infestation of the mussel in Lake Kasumigaura must have occurred not later than 2004.
