FRV Alba Na Mara 0823A
Cruise summary report
| Cruise Info. | |
| Ship name (ship code) | FRV Alba Na Mara (74NM) |
| Cruise identifier | 0823A |
| Cruise period | 2023-06-02 — 2023-06-16 |
| Status | Completed |
| Port of departure | Fraserburgh, United Kingdom |
| Port of return | Fraserburgh, United Kingdom |
| Purpose | Research |
| Objectives | Objectives
1. To conduct a fisheries acoustic survey to assess the distribution and abundance of pelagic fish in the Moray Firth OWF development sites. To undertake an acoustic survey of sandeels and clupeid fish in the water column using 38 and 120 kHz. Concentrations of fish will be sampled using the pelagic trawl. Species composition and length frequency distributions of fish caught will be determined. Subsamples will be weighed and their otoliths removed to establish length-weight relationships and age composition. 2. To conduct RoxAnn survey of the substrate along the acoustic survey track. 3. To conduct a demersal fishing survey in the Moray Firth adjacent to the Windfarm sites. To assess abundance, length-frequency-distribution, and weight-at-length of demersal fish at fixed stations in the Moray Firth region by demersal trawl survey. Samples will be retained for energy content analysis at a later date. 4. CTD and FLNTU. To sample variation in water temperature, conductivity, turbidity and chlorophyll-a through the water column using a SBE CTD sampler and Fluorometer at all demersal trawl stations and additional where required. Narrative Alba na Mara departed Fraserburgh harbour by 09:40 hours on 2 June 2023 after all scientific staff had joined the vessel. Alba na Mara steamed towards transect number 12 and started acoustic surveying after completing a CTD station. Surveying continued till some marks suitable for fishing were detected in the sounder and the pelagic, mid-water net (PT154), was deployed to sample the identified marks. Issues with the CTD winch and the discrepancies between its amount of paid out wire and the actual depth indicated by the sounder were investigated and solved on 4 June. Acoustic surveying along the predetermined transects, CTD sampling and fishing continued daily till 5 June when Alba na Mara sailed towards Scapa Flow in Orkney to calibrate the EK60 equipment. Given Scapa Flow’s sheltered nature it is often an optimal location choice for calibration. Alba na Mara anchored at Scapa Flow from the evening of 5 June and began calibrating the 200 kHz frequency till 22:00 hours. Alba na Mara anchored in Scapa Flow for the night. The following day the calibration continued and was completed successfully for all frequencies. Alba na Mara then slowly made passage south towards the south part of Transect 1 in readiness to restart the acoustic survey on the morning of 6 June. Once Transect 1 was completed the survey continued south by steaming towards Transect 13 and completing it by 17:00 hours. Along Transect 13 some small marks were seen on the sounder and were fished on with the pelagic net. After the haul Transect 13 was restarted and completed by 17:00 hours. Given the distance to the anchorage planned for that evening at Spey Bay the Alba na Mara started steaming on completion of the Transect. The survey continued on 8 and 9 June with one more fishing event at Transect 14. On the Evening of 9 June the Alba na Mara went to Fraserburgh harbour and moored up. On Saturday 10 June the fishing gear was changed from the pelagic net (PT154) to the bottom trawl (BT158). This was completed by the afternoon of that day. The acoustic technician disembarked at this point. The Alba na Mara stayed in Fraserburgh harbour for the night of Saturday 10 June. The following day (11 June 2023) the ship left Fraserburgh harbour at 07:00 hours and did a "shakedown" trawl 10 NM northwest of Fraserburgh to ensure the BT158 was fishing correctly. After this successful trial the ship steamed towards a tow in the vicinity of Transect 14 and deployed the BT158 for a 30 minute sample. Fish were processed and samples were retained for bomb calorimetry work. Table 1 shows the main species per haul. Two hauls were unde |
| Chief scientist | Robert A K Main (Marine Scotland Aberdeen Marine Laboratory) |
| Cruise programme |  (0.41 MB) |
| Cruise report | (0.79 MB) |
| Ocean/sea areas | |
| General | North Sea Unknown |
| Specific | Moray Firth |
