Marine

MRV Scotia: Survey 1615S Programme

October 29, 2015 by Marine Directorate Communications 1 Comment | Category Compliance, Marine Directorate general, Marine Directorate Science, Research Vessel Surveys

Duration: 4-15 November 2015

Fishing Gear:

GOV Trawl (BT137) and ground gear B and new light rockhopper (E rig).
2 sets ground gear bags (port, starboard and center).

Objectives:

1. To compare the catchability of a GOV trawl rigged with a new light rockhopper ground gear (E Rig) against the same net rigged with the bobbin ground gear rig (B Rig) use during IBTS North Sea surveys. Catchability will be assessed using the ground gear ‘bagged’ technique.
2. To obtain under water TV footage of ground gear contact, adjuster chain assembly and mid-bridle orientation.
3. To carry out instrumented gear measurements using self-contained load-cells and Scanmar to assess bridle loads and net drag.

Procedures:
Loading of all trawl gear will take place on 2 November. Loading of all other scientific equipment will take place on 2 and 3 November with all equipment being set up and tested by the evening prior to sailing. Scotia will sail on 4 November and (after all safety drills and a shakedown trawl shoot), thereafter, commence fishing operations on suitable GOV tows East of Aberdeen, Moray Firth or East of the Orkney Islands. Weather conditions at the time will determine the exact start area. Trawling operations will be conducted from 07:00 hours until 21:00 hours and the survey schedule and operations will be decided by SIC after daily consultation with Fishing Master and Captain.

Fishing:
The plan is to start the survey with the new light rockhopper gear (E Rig) and undertake TV observations and instrumentation trials. Once these have been completed the ground gear bags will be attached and catchability data collected. It is anticipated the duration for the observation and instrumentation hauls will be up to two hours (codend untied) and for the ‘bagged’ catchability tows 15 minutes (codends tied). Once sufficient hauls have been made with the rockhopper ground gear the GOV trawl will be re-rigged with ground gear B and the process repeated.

During the instrumentation hauls the tow procedure will consist of blocks (15 minute periods while towing at constant rpm) for three different speeds. Once the 15 minute blocks have been completed for each speed the vessel will turn and the same procedure repeated in the reciprocal direction. Prior to turning, the gear will be hauled until the ground gear is on deck and once turned then redeployed. The number of speed ranges will be dependent on the prevailing weather and may be reduced.

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• MRV Scotia: An update on survey 1615S says:

  13 November 2015 at 12:21 am

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