FRV Scotia 0702S
Cruise summary report
|Ship name (ship code)||FRV Scotia (748S)|
|Cruise period||2002-04-26 — 2002-05-10|
|Port of departure||Aberdeen, United Kingdom|
|Port of return||Aberdeen, United Kingdom|
|Objectives||1. To assess the performance of a newly designed small mesh cod end liner (9mm) with respect to its effect, if any, on the geometry and water flow in the cod end of the trawl.
2. To mount a low light CCD camera on the trawl extension in order to make quantitative counts of fish passing into the cod end which can be correlated with cod-end catches as a comparison with, and back up to, the small mesh liner.
3. To obtain quantitative information on fish populations in the mouth of the trawl and between the wings using the Reson Seabat mounted on the RCTV along with simultaneous video footage using the SIT and ccd cameras, where possible, to give information on species identification. These data will be compared with data collected in Nov/Dec.
4. To use the Seabat to make an assessment of possible areas where fish escapes are high in the GOV trawl.
Scotia sailed at 1030h on 26 April and headed for fishing grounds in the Moray Firth. Some experimental tows were carried out with net cameras in different positions, but difficulty was experienced with the RCTV-Seabat system, which resulted in the Scotia returning to Aberdeen on Monday 29 April to carry out repairs and tests. Scotia sailed again at 1900h for the Buchan Deeps (57.44' N, 1.26' W) where instrumentation tows for objective 1 were carried out. These instrument trials were successfully completed and, following further experimental camera tows, Scotia exchanged personnel in Peterhead on Friday 3 May.
During the second week between 5 and 7 hauls were achieved each day during daylight hours, towards objectives 2,3 and 4. Standard tows of 30 minutes using the multibeam sonar on the RCTV and low light ccd cameras positioned on the net monitor the fish population entering the trawl were carried out in two areas (59.2' N, 2.3' W and 58.8' N, 2.4 W). A photomultiplier was used to make light intensity profiles of the water column at the start and end of each haul. A further 5 developmental tows tested the Simrad SM2000 multibeam and experimented with weights and a depressor fin to improve the performance of the RCTV. Scotia steamed for Aberdeen at 1800 hours on Thursday 9 May and docked in Aberdeen harbour at 1000 hours on Friday 10th of May.
|Chief scientist||Emma Jones (Fisheries Research Services Aberdeen Marine Laboratory)|
|Project||Whole Gear Selectivity|
|Coordinating body||FRS Marine Laboratory|
|Cruise report||(0.16 MB)|
|Specific||Orkney, Moray Firth|
|Optics (eg underwater light levels)||Quantity: number of profiles = 26|
Description: Profiles of light intensity (Log lux) through the water column using a photomultiplier
|Biology and fisheries|
|Demersal fish||Quantity: number of hauls = 30|
Description: GOV hauls (30 min), catch worked up as per IBTS protocols
|Acoustic reflection on marine organisms.||Quantity: number of hauls = 30|
Description: GOV hauls where multibeam acoustic data was collected on fish populations in the mouth of the net
|Gear research||Description: Instrument tows collecting data on water flow and warp tensions at different towing speeds|
|Other biological/fisheries measurement||Quantity: number of hauls = 30|
Description: GOV hauls where video footage was recorded of fish passing into the net and along the extension (30 hrs)