Comparison of fish assemblage structures between reed stands and bulkheads in Lake Kitaura, Ibaraki Prefecture, Japan

Abstract

Daytime sampling using a seine net was conducted at Lake Kitaura, Ibaraki Prefecture, Japan, in April, June and August 2009 and 2010, to determine differences in fish assemblage structures between littoral reed stand areas and adjacent bulkhead areas in which reed stands had completely disappeared. The mean numbers of fish species and individuals per tow were significantly greater in the reed areas than the bulkhead areas in most months in both years, although a similarity index did not indicate differences in species composition of the fish assemblages between the two areas. In addition, individual densities of most of the dominant species, including the gobiid Tridentiger brevispinis and the cyprinid Pseudorasbora parva, were more abundant in the reed areas compared with the bulkhead areas, although the opposite was found for the salangid Salangichthys microdon. These results suggest that the construction of bulkheads in littoral reed belts greatly influences associated fish assemblage structures.