FRV Clupea 1306C
Cruise summary report
|Ship name (ship code)||FRV Clupea (74CU)|
|Cruise period||2006-09-19 — 2006-10-06|
|Port of departure||Fraserburgh, United Kingdom|
|Port of return||Fraserburgh, United Kingdom|
1. To measure the immediate physical, ecological and environmental impact of a roller clump over a range of sediment types.
2. To observe performance of modified trawl doors and extend the techniques used in the first objective to trawl gears.
3. To conduct engineering trials on newly developed ship-borne and towed instrumentation and hardware (3 - 6 October).
During the course of the cruise sidescan sonar and Roxann readings were recorded and grab samples taken along the 20m contour from Sandend Bay to Nairn. A provisional assessment of the grab samples identified sediment types in the range from medium-fine sand to mud. These data were used to identify three sites (a) medium-fine sand (Cullen Bay - Sandend Bay), (b) fine sand (Lossiemouth - Burghead) and © mud (Nairn Bay) where the roller clump could be towed at diveable depths. Three or more tows of the roller clump were carried out at each of these sites. In each case divers on the towed underwater vehicle (TUV) recorded the impact and took water samples at five positions in the sediment plume in the wake of the clump. After hauling a pair of divers measured the physical impact of the roller clump using a laser-camera profiler. And subsequently another pair took three core samples inside and three outside the track of the roller clump.
The physical impact of the roller clump varied from a flattening of ripples on medium-fine sand to a 10-15cm trench in soft mud. In all cases the sidescan sonar could detect the path of the roller clump. The marks were very strong for the tows in mud and weaker for the compacted sandy sediments.
The sediment plume samples were filtered, subsampled and stored on board the Clupea. Analysis of the suspended solids, particle size and nutrient will take place on return to the Laboratory. The core samples were sieved over a 0.5mm mesh and stored in formaldehyde on the Clupea.
|Chief scientist||F G O'Neill (Fisheries Research Services Aberdeen Marine Laboratory)|
|Cruise report||(0.03 MB)|
|Specific||North East Coast of Scotland|
|Bottom deposits||Quantity: number of stations = 3|
Description: At 3 or more sites. Water samples at 5 positions in the sediment plume in the wake of the roller clump were taken. Sediment plume samples were filtered, subsampled and stored.
|Biology and fisheries|
|Gear research||Quantity: number of deployments = 7|
Description: 7 tows. Carried out on a modified benthic sledge in water depths of about 20m.
|Geology and geophysics|
|Core - soft bottom||Quantity: number of cores = 6|
Description: 3 inside and 3 outside the track of the roller clump. Samples sieved over a 0.5mm mesh and stored in formaldehyde.
|Bottom photography||Quantity: number of deployments = 7|
Description: A small TV-camera platform was towed alongside the benthic sledge to enable real-time observation of the sandclouds.
|Bottom photography||Quantity: activity duration in days = 3|
Description: Dicers in the TUV recorded the various components of the modified Morgere trawl. Laser-camera used to profile the impact of the Morgere trawl doors, sweeps and groundgear and the physical impact of the roller clump.
|Long/short range side scan sonar||Quantity: activity duration in days = 27|
Description: Sidescan sonar and Roxann readings were recorded during the course of the cruise