A Fishy Business

Farming in a traditional way brings enormous benefits for wildlife. Here on the Sudbury riverside the Sudbury Common Lands Charity is currently able to continue the ancient tradition of livestock grazing which has disappeared from much of the Stour valley to be replaced by intensive arable farming.

So what benefits might wildlife enjoy on the riverside? Perhaps the most important is the abundance of insects associated with cattle grazing from dung flies to midges. Through the summer months these insects attracts house martins, swallows and swifts to feed over the pastures. The martins and swallows also collect mud for their nests from the shallow river margins where the cattle trample. These areas also attract fish fry that love the warm shallows and in turn they provide food for the kingfishers which still nest every year in the river banks.

The charity has planted thousands of trees and shrubs and although there are sometimes calls to remove these where householders’ views are reduced the benefits are enormous and perhaps no more so than along the river itself. Here overhanging branches provide areas for fish to spawn, rest and feed. The Sudbury pastures form a single link in what should be a continuous chain along the length of the Stour. Up until the end of the Second World War this was indeed the case. Just before the war author Julian Tennyson walked what must have been a valley of unsurpassed loveliness and richness in wildlife. He recorded that the water meadows followed every inch of the river until it disappeared over the border into Cambridgeshire. Sean Fielding wrote in his forward to the book that his friend had given his life (killed in action in 1945) ‘so that she (England) might continue her unhurried way down the avenues of time’. In 1946 the RAF photographed the entire valley and those meadows and pastures were still intact. Since then the majority have disappeared under the plough and life is anything but unhurried. The Suffolk River Valleys Environmentally Sensitive Area Scheme of the late 1980s onwards attempted to turn the clock back by providing grants for arable reversion back to grassland but once ancient pastures with their native flora are ploughed up they may take centuries to regain their former diversity.

All this was brought home last month when the Environment Agency carried out its annual fish stock check on the Sudbury Common Lands. This exercise is vital as it records the numbers and health of the fish and year on year comparisons can be made. Whilst the officers carried out the work the cattle came to drink and stand in the water, a kingfisher gave its alarm call and dragonflies flew back and forth. What seemed to be a lazy day on the river was in fact a busy day of catching, checking, measuring and recording fish details. There is, of course, a delay in obtaining the report for the entire river but the Sudbury fish looked very healthy. There were sizable chub which is a good sign as they eat signal crayfish which have become much more numerous in Sudbury having moved downstream from their Liston stronghold. They are not native and so are not welcome so if they provide a good feed for fish then so much the better. Among the native fish caught on the day was a small bleak which is not part of the fish fauna of the Stour. It favours weirs and pumping stations and this species has been “pumped” though the Ely Ouse transfer system. It requires relatively good water quality and as there have been concerns about water quality and subsequent fish kills over the past two years that must be good news. Although fish stock have declined, news of an increase in European eel simply masks the disastrous situation in which this species finds itself but any increase must be cause for some celebration.