CFV Urchin 1607H
Cruise summary report
|Ship name||CFV Urchin|
|Cruise period||2007-05-08 — 2007-05-11|
|Port of departure||Craobh Haven, United Kingdom|
|Port of return||Craobh Haven, United Kingdom|
To conduct a video survey to assess for the benthic impact of scallop dredging along pre-defined transects, using both ROV and diver operated systems.
ROV loaded and set up. ROV deployed with 2 x 75m lengths of neutral buoyancy cable. Interference experienced when approximately 100m was coiled off the cable drum (this problem was consistent throughout the trip when these two cables were used). Westerly weather and time restrictions limited site opportunities. Initial trials and equipment familiarisation were undertaken to the north end of Shuna. Six (R1 - R4) familiarisation dives were taken in this location.
Five dives (R5 - R9) were then undertaken on the east side of Luing, outwith the SAC, but in a location where there was reported scallop dredge activity. Much time was spent troubleshooting the cable fault, and discussing the work with stakeholders on the telephone (DD).
Again, weather limited operations and the only workable location where data indicated dredging had occurred was off the east coast of Scarba. Ten dives (R10 - R19) were undertaken in this location.
Work focussed on the Garvellachs, the most westerly group of islands in the SAC. Damage has been reported by recreational divers in this area in the Dun Chonnuill channel in 2007. This is a very tidal area, which made ROV deployment challenging. Two dives (R20 & R21) were undertaken at this location in the morning, and a further six (R26 - R31) were undertaken in the afternoon. R31 had to be aborted and the ROV recovered and redeployed due to insufficient cable length. Three dives (R22 - R24) were undertaken along the sediment reef interface to the southwest of A'Chuili in the area of Sgeir nam Marag. There was quite a heavy swell at this site, following the previous days of wind.
ROV cable re-rigged with 40m sinking line inserted between the two 75m neutral density lengths in an attempt to increase the depth capability of the unit. Based on intelligence received from the dive team's activities on 9 May, one (R32) drift dive was undertaken through Dun Chonnuil channel. Footage from this dive clearly shows obvious sorting of cobbles into parallel lines.
Two dives (R33 & R34) were undertaken to the northwest of Garbh Eileach, at the westerly end of Dun Connuill channel.
Two dives on the west side of the Garvellachs (R35 & R36) on a previously unrecorded reef. Two further dives were undertaken to the east of Garbh Eileach.
The final three dives of the trip (R39 - R41) were undertaken on the west side of Luing. Recovery of the ROV into the boat was recorded at this location (R40). Equipment dismantled.
Equipment offloaded and containers packed. Demob and returned to respective bases.
|Chief scientist||Mike Breen (Fisheries Research Services Aberdeen Marine Laboratory)|
|Cruise programme||(0.02 MB)|
|Cruise report||(0.11 MB)|
|General||Inner Seas off the West Coast of Scotland|
|Specific||Firth of Lorn|
|Track charts||(0.05 MB)|
|Geology and geophysics|
|Bottom photography||Quantity: number of dives = 13|
Description: scuba dive locations D5 - D17