River fish populations in a Suffolk beauty spot have seen an upturn.

A three yearly survey carried out by the Environment Agency in East Anglia looked at fish numbers and species along the River Stour at Dedham.

Apart from 2021 - when the survey was not carried out due to the Covid pandemic - the team recorded their best results for fish numbers in recent years.

The number of species equalled the highest - suggesting the fish population in the river has improved. Surveys carried out 2015 and 2018 had fewer individual fish and fewer species than in 2024.

The team on the River Stour caught 15 species and more than 600 fish including eel, chub, roach, bleak, dace, tench, pike, bullhead, spined loach, gudgeon, perch and flounder. At the end of the survey all of the fish get returned to the river and the nets are removed.

Fish being counted and measured (Image: Environment Agency)

Dan Hayter - who monitors fish in rivers for the Environment Agency - said the survey was carried out using "electric fishing" - which involves passing a mild electrical field through the water to temporarily immobilise the fish to allow the team to catch them.

"To conduct a fish survey, we measure out a 100-metre stretch of the river and place a large stop net at the start and end of the stretch to prevent fish moving in and out during the survey," he said.

"Four of us then get in a motorised boat and travel along the stretch with specialised electric fishing equipment.

"We usually have one person manoeuvring the boat, two people operating the handheld electrodes (stainless steel hoops on the end of a long pole) and one with a net catching the fish, moving them to a recovery, and holding container ready for us to count."

The National Monitoring Field Team undertake fish surveys along all the main rivers and tributaries in East Anglia.

This is done yearly on some sites and every three years on others - depending on a number of factors including fisheries interest and the size of the river.

"Electro-fishing may sound a little scary, but it is harmless to the fish and is a very humane way of catching them and allowing us to carry out this vital work," said Dan.

"We carry out these fish surveys for several reasons. It is obviously useful for the millions of anglers out there to know information about fish stocks, and it also gives us a good indication of the health of the river."

Surveys can take up to 10 to 12 hours on a very busy day, he added.

"The more fish there are, the more there are to count and therefore the longer we are there," he said. 

"When conducting the survey, we start in the middle of the stretch first and then go along the sides, using the current to safely capture the fish. We then repeat this once or twice more to ensure we have a good capture efficiency and get accurate fish data."

The Environment Agency has 40 years of data for this stretch of river making it one of the best data sets for electric fishing in the UK.