This study describes the current status of the small
fish community in Niushan Lake in China, and examines the spatial and
seasonal variations of the community in relation to key environmental
factors. Based on macrophyte cover conditions, the lake was divided into
three major habitat types: (1) Potamogeton maackianus habitat, (2) Potamogeton maackianus and Myriophyllum spicatum habitat, and (3)
uncovered or less-covered habitat. Fish were sampled quantitatively in the
three habitat types by block nets seasonally from September 2002 to August
2003. A total of 10 469 individuals from 27 fish species were caught, among
which 20 species were considered as small fishes. Rhodeus ocellatus, Paracheilognathus imberbis, Pseudorasbora parva, Micropercops swinhonis and Cultrichthys erythropterus were recognized
as dominant small fishes according to their abundance and occurrence. It was
noted that (1) small fishes predominated the total number of fish species in
the lake, which reflected to some degree the size diminution phenomenon of
fish resources; (2) many small fishes had plant detritus as their food item,
which was consistent with the abundance of macrophyte detritus in the lake
and implied the importance of detritus in supporting small fish secondary
production. Canonical correspondence analysis suggested that the spatial
distributions of most small fishes were associated with complex macrophyte
cover conditions. Macrophyte biomass was positively correlated with species
richness, diversity index and the catch per unit of effort (CPUE) of the fish community. Water depth had no
significant effects on species diversity and distribution of the small
fishes. Correspondence analysis revealed a higher occurrence of the small
fishes and higher abundance of individuals in summer and autumn. Seasonal
length-frequency distributions of several species indicated that more larval
and juvenile individuals appeared in spring and summer. This study provides
some baseline information which will be essential to long-term monitoring of
small fish communities in the Yangtze lakes.