Abstract
In the absence of previous investigations the present study considers fish populations in the Medway (England) Estuary; their type, composition and migration patterns. Seasonal growth of first‐year plaice and flounder is also investigated. Fish were sampled monthly between 1973 and 1975 using power station trash screens as the quantitative sampling method. A total of 46,228 fish, 49 species and weighing 325.0 kg were taken. Monthly samples were dominated by sprats which, with 13 other species, formed more than 90 percent of the catch in most months. Based on seasonal distributions and length‐frequency changes in consecutive months a model of fish migration patterns was constructed. In most cases emigration and immigration were separated by one or more months between spring and autumn, while in clupeoids they appeared to occur coincidentally during spring and summer.