Relationships between short-term variations in density of juvenile yellowfin goby <Emphasis Type="Italic">Acanthogobius flavimanus</Emphasis> and environmental variables on an estuarine mudflat

Weekly variations in density of juvenile yellowfin goby Acanthogobius flavimanus with a variety of environmental variables (e.g. water temperature, salinity and transparency, and prey density) were investigated on a tidal mudflat within the Tama River estuary, central Japan, from March to July 2001. Metamorphosing newly settled juveniles occurred from mid-March to late May. Metamorphosed benthich juveniles first appeared in late March, the density sharply increasing to a peak (67.0 ind./m²) in early May but rapidly decreasing to less than 10% of that two weeks later. No consistent relationships were apparent between short-term variations in fish density by developmental stages and water temperature, or salinity. In contrast, a weak negative relation was found between juvenile density and water transparency. Further, benthic juvenile density was positively related to short-term fluctuations of errant polychaetes, which is one of the main prey items.