SEASONAL SURVEY OF FISH POPULATIONS IN THE LOWER MEDWAY ESTUARY, KENT, BASED ON POWER-STATION SCREEN SAMPLES

Quantitative samples were collected from the cooling-water intake screens at Kingsnorth Power Station between May 1973 and August 1975. The sampling method is discussed and the catch compared with trawl samples taken in the vicinity. A total of 46 228 fish, 49 species and weighing 325·0 kilograms were taken in 39 screen samples. Numerically the monthly samples were dominated by Sprattus sprattus (L.) and twelve other species which together formed more than 90% of the catch in most months. Short-term fluctuations in catch were marked but superimposed on this was a clear seasonal cycle; numbers of species, numbers of individuals and total weights of catch reached maxima in winter and minima in summer. The three diversity indices measured displayed no definite seasonal pattern, the result of fluctuations in sprat numbers. © 1979.