A fish counter network for monitoring Scottish salmon stocks
This report outlines the SG's need for data on salmon returning to rivers, and the different types of in-river fish counter that are currently available. The report identifies the locations of existing fish counters and some other sites that may be suitable for new optical or resistivity counters.
7. Current developments
Most of the counters shown in Figure 1 are not located near the mouth of their respective rivers, making their data unsuitable for use in assessing whole river salmon stocks. Until 2018, Scottish and Southern Energy plc (SSE) provided data to the Marine Directorate from counters on their hydropower assets. Latterly, those counters were unreliable and SSE are replacing them with new resistivity counters and/or optical systems that utilise video cameras and machine learning algorithms to detect and count fish. Three of the new SSE counters are in locations that may be useful to inform the national assessment of salmon stocks, whilst one would inform on statutory site condition monitoring of a salmon SAC but could not be used in wider stock assessment. SSE and Marine Directorate are currently exploring how best to establish a data sharing arrangement for SSE to allow an evaluation of the data. Resistivity count data have been received for the River Ugie and the usefulness of this is being assessed. Data from two further counters were found to be either unsuitable (incomplete count) or were not made available to the Marine Directorate.
Two Marine Fund Scotland (MFS) grants (totalling £274,000) were awarded in 2024 to Fisheries Management Scotland (FMS) for the development of Machine Learning tools to improve the automation and efficiency of fish counting on the rivers Laxford, Deveron and Ayr. This investment should reduce the human resource required to deliver high quality data, and may be of benefit to many providers. Further MFS grants were awarded in 2024 to the Stornoway Angling Association (£143,204) and the Esks District Salmon Fishery Board (£230,000) for the installation of new fish counters on the rivers Creed and North Esk. The latter is intended to supplement the long-term data set (1981 to 2022) obtained by the Marine Directorate at Logie Mill. Once validated, the data from these new counters may be suitable for use in assessing stocks across the country.
Contact
Email: craig.robinson@gov.scot