Seasonal changes in the structure of a reed stand fish assemblage in Lake Kitaura, Ibaraki Prefecture, Japan

Seasonal patterns of fish assemblage structures in a reed stand area were examined in Lake Kitaura, central Japan, from April 2009 to March 2011. A total of 13,892 individuals (mainly larvae and juveniles) representing 9 families and 22 species were collected monthly by small seine net (mesh size 1 mm) throughout the study period. The numbers of fish species and individuals increased from spring to early summer in each year, with the highest species and individual numbers in June. The most abundant species were the gobiid Rhinogobius sp. (47.1. of the total number of individuals collected during the study period), the centrarchid Lepomis macrochirus macrochirus (19.8.), the gobiid Tridentiger brevispinis (12.5.), the salangid Salangichthys microdon (8.4.), the gobiid Gymnogobius urotaenia (3.6.), the cyprinid Pseudorasbora parva (2.9.), the osmerid Hypomesus nipponensis (2.0.) and the hemiramphid Hyporhamphus intermedius (1.4.). Based on the occurrence patterns and developmental stages of fishes sampled, it is suggested that the reed stand was used as a place of temporary growth and residence by a variety of fishes.