Report on the 2023 razor clam survey in the Firth of Clyde and the 2024 to 2025 survey in the Solway

This report describes surveys carried out in the Firth of Clyde in the autumn of 2023, and in the Solway in January and December 2024, and January 2025 as part of the Scottish Government’s scientific trial into electrofishing for razor clams. Working with fishers, scientists deployed a towed video camera rig behind the electrofishing gear recording the densities and sizes of the pod razor clam, Ensis siliqua. The data from the Ayrshire coast (Firth of Clyde) shows that the average density of pod razors (of all sizes) in the permitted fishing area was 0.47 m-2. Tows were also conducted for comparison at three sites outside of the trial fishing grounds where the average density was shown to be slightly higher at 0.72 m-2. It was also possible to compare the new data with a previous survey conducted in 2017 and this showed that during the scientific trial young razor clams (smaller than 100 mm shell length) have settled in the fished sites. The comparison also showed that there has been a decline in the densities of legal-sized Ensis siliqua (those larger than 100 mm shell length) in Irvine, Ayr and Turnberry Bays, but an increase in densities of this size class in Culzean Bay. The survey in the Solway had to be split across several periods being affected by high levels of silt from freshwater run-off combined with strong tides and periods of poor weather. The survey comprising 49 tows in total was finally completed in January 2025 and the tows from both years were combined to improve the overall coverage. The average density of E. siliqua of all sizes across Wigtown, Fleet and Kirkudbright Bays was 0.99 m-2. There were also some spatial differences with densities of legal sized razors being higher in Fleet Bay compared to the other locations. As well as adding new scientific data for the Firth of Clyde and the Solway, the comparison between the Ayrshire coast 2017 and 2023 data shows that repeated surveys using towed video can add valuable insights into how the razor clam populations are changing over time.