FRV Scotia 0813S
|Ship name (ship code)||FRV Scotia (748S)|
|Cruise period||2013-07-10 — 2013-07-29|
|Port of departure||Aberdeen, United Kingdom|
|Port of return||Aberdeen, United Kingdom|
1. To conduct an acoustic survey to estimate the abundance and distribution of herring in the north western North Sea and north of Scotland between 58°30'-62°N and from the shelf edge to 2°E, excluding Faroese waters.
2. To obtain biological samples for echosounder trace identification using a pelagic trawl.
3. To obtain samples of herring for biological analysis, including age, length, weight, sex, maturity and ichthyophonus infection.
4. To obtain hydrographic data for comparison with the horizontal and vertical distribution of herring.
5. To obtain dry weight estimates of macro zooplankton biomass throughout the study area for comparison with acoustically derived plankton biomass estimates and observed herring distribution.
All gear will be loaded onto the vessel on Sunday 7 July. Marine Scotland staff will fit acoustic transducers for control of the multisampler net to the drop keel prior to sailing. The vessel will depart Aberdeen on 10 July and head for Scapa Flow, Orkney Islands, where calibration of all echosounders will take place (approximately 8-12 hours at anchor). Crew training and trial deployments of fishing gear and the multi sampler will take place en route as required by the fishing master.
The survey will commence after calibration and follow a pattern of parallel transects running east/west, at normal steaming speed (10.5 knots), progressing northwards, along the east side of Orkney/Shetland, and southwards along the west side. The survey area is bounded by 58°30'-62°N and 02°E to the 250 m contour. This survey includes an additional area previously surveyed by the West Coast charter (V1a) (South). In order to cover the additional area, transect spacing is 15 nm for the entirety of the survey area. A pelagic vessel will be chartered to conduct an acoustic survey simultaneously with Scotia by interlacing between these transects giving an effective transect spacing for the combined surveys of 7.5 miles. The proposed Scotia survey design is shown in Figure 1. The charter vessel will not collect biological samples other than those obtained during its commercial tow(s).
A half landing will take place on approximately 19 July in Lerwick to allow for the transfer of staff and to comply with the WTD policy. A scientific crew change will take place with R G-Mules joining the vessel and L Ritchie leaving. A calibration will be conducted either east of Shetland after the mid cruise break or in Orkney at the end of the cruise if time permits.
Acoustic data will be collected at four frequencies (18, 38, 120 and 200 kHz) between 0300 and 2300 hours. Fish shoals seen on the echosounder will be identified using a pelagic trawl (PT160). Survey trawling operations will be carried out between two and four times per day at anytime between 0300 and 2300. Fishing operations will normally be carried out using the multisampler cod end unless large aggregations are seen in the area. Samples of all species caught will be measured for length to partition the echo integral amongst species and size classes for target strength functions. Fish will also be weighed to establish a length-weight relationship. In the survey area east of 4° W, otoliths will be collected from a sub-sample of the herring to determine age according to three length strata, two per 0.5 cm class below 22 cm, five per 0.5 cm class from 22.5 - 27.5 cm and ten per 0.5 cm class for 28.0 cm and above. In the area west of 4° W, random sampling of 120 fish above 24 cm length will be carried out for each haul with photographs taken for maturity analysis. Where there are herring below 24 cm, or missing length classes, a further sample will be analysed to ensure there will be ages
|Chief scientist||Philip J Copland (Marine Scotland Aberdeen Marine Laboratory)|
|Project||ICES International North Sea Herring Acoustic Survey|
|Coordinating body||International Council for the Exploration of the Sea (ICES)|
|Specific||Orkney and Shetland|
|Track charts||(00 MB)|