Razor clam trial: annual report 2023-2024

7. MD Evidence Data and Digital

The Science, Evidence, Data and Digital (SEDD) Portfolio of the Marine Directorate of the Scottish Government continue to take responsibility for the biological and ecological goals of the razor clam trial;

• to gather local level information on razor clam populations and stocks, including accurate data gathered by trial participants to supplement stock survey work;
• to ensure sustainable harvesting levels; and,
• to gather further information about the impacts of the electrofishing method on target and non-target species.

During the sixth year of the trial (1 February 2023 to 31 January 2024) work was focussed on collating available information, completing analyses, progressing long term data storage options (internal database) and writing the report (covering trial years 1 to 5) to document the progress on the biological and ecological goals of the razor clam trial. This report is now published:

Scottish scientific electrofishery for razor clams trial - biological and ecological goals: progress report - gov.scot (www.gov.scot)

With further information on the razor clam trial available through an online dashboard:

RazorClamTrial (shinyapps.io)

All data collected as part of the razor clam trial are collated in an internal database and work is underway to produce publicly available data layers through the National Marine Plan platform (Marine Scotland - National Marine Plan Interactive (atkinsgeospatial.com))

Fishers continue to send monthly self-samples which provides information on the length of landed razor clams. As a minimum, vessels submit one sample per month when fishing. Between August 2018 and January 2024, a total of 549 razor clams sample sheets were submitted to the Marine Directorate (Table 1).

All vessels participating in the trial carry Remote Electronic Monitoring (REM) systems which record details of vessel position, speed, and the current (amperes) output of the generator used to power the electrofishing gear at 10 second intervals. Official Scottish landings and effort data are collated by Marine Directorate Operations from fishers’ logbooks and sales notes. These data are utilised for several purposes including in combination with information on vessel activity (as detected by on-board REM systems) to monitor fishing activity, in the calculation of landings per unit effort (LPUE) and in stock assessments. Further details are available in the published report and dashboard listed above.

In year six of the trial, REM recorded 22 vessels fishing across the four trial zones, in six trial areas (Table 2). The highest number of vessels are in the West Coast SW zone, with 10 vessels fishing within the Firth of Clyde trial area. In total across year six there were 1,517 days of fishing activity. The zone with the highest number of days of fishing activity was West Coast SW with 789 days, with fishing activity highest in the Firth of Clyde trial area (687 days). On average across all areas vessels were fishing for 366.7 minutes (~6 hours) each trip (Table 2).

A PhD project is on-going (in collaboration with the Scottish Association for Marine Science (SAMS)) to assess the ecological sustainability of a well-controlled electro fishery for razor clams in Scottish coastal seas. Further details can be found in the report detailed above.

Marine Directorate continue to work in collaboration with SAMS and trial participants to undertake surveys for razor clams. Surveys to determine razor clam densities were conducted in the Sound of Harris and Firth of Clyde in 2017 (prior to the trial commencing) (Fox, 2018). This work established the application of electrofishing with towed video as a new survey method for razor clams (Fox et al., 2019). Using this methodology, a survey of the Tarbert Bank was completed in February-March 2023 (Report on razor clam surveys on Tarbert Bank - gov.scot (www.gov.scot)) and the Clyde trial area (October 2023).