Report from the forth Fish Survey conducted by the RDA and the Institute of Fisheries Management July 2025 by Steve Colcough

Introduction by Richard Verrill

Estuaries are vital habitats for fish, playing a crucial role in the life cycle of many species. It is well recognised that estuaries are particularly useful in helping to support young fish stocks. Different species favour different habitat which might include gravel / sand beaches, mudflats, saltmarshes and sea grass. The River Deben can provide all of these.

Historically there was very little data about the young spawn fishes that used the Deben for their early development. Occasionally Eastern Inshore Fisheries Conservation Authority (EIFCA) or The Environment Agency have done surveys and collected some data but this had ceased after surveys done in 2013 and 2014. Stephen Thompson from EIFCA approached the RDA in 2019 suggesting that the RDA and some volunteers might like to be involved with some Citizen Science. We formed a group of RDA volunteers and had training from EIFCA and The Institute of Fisheries Management (IFM) hosted at Hazelwood Marshes and arranged by Suffolk Wildlife Trust (SWT).

The RDA started to survey small fish in the Deben with the guidance of Steve Colclough from the IFM in 2022 based at Bawdsey. Since 2024 we have also surveyed the shore at Martlesham Wilds in conjunction with SWT. We now have 4 years of data and this has been shared with EIFCA and the IFM together with the UK Bass Association which is sampling bass in the West country. Our volunteer group has remained enthusiastic and the group has evolved and grown with time. I am most grateful for this support, as without, we would be unable to add to our data which has filled quite a gap in Deben fish data.

Estuaries are very dynamic environments and so results can also be very variable, however, with repeated surveying we should be able to build a much better picture of the health of our young fish stocks. The RDA intends to continue with this Citizen Science. Below is our data collected in 2025 and data for all years from 2022 is available on the RDA website.

Full Report – River Deben Fish Survey 2025

Previous survey reports – 2022; 2023, 2024