Marine Scotland

MRV Alba na Mara: Survey 2016A Programme

October 20, 2016 by No Comments | Category Marine Scotland Compliance, Marine Scotland general, Marine Scotland Science, Marine Scotland Surveys, Research Vessel Surveys

Duration: 2 – 13 November 2016

Gear:

  • Prawn trawl BT 201;
  • Deep Vision Camera and lights (supplied by IMRB);
  • Net mounted camera system;
  • Turbidity meter;
  • Scanmar instrumentation; and
  • 600mm Square Mesh Panel (SMP).

Objectives:

  • Primary: To obtain Deep Vision footage from a demersal trawl on different ground types and turbidities: typical nephrops grounds (mud), clearer demersal grounds (sand, gravel) and turbidities and compare data from recorded footage with actual catches in each instance.
  • Secondary (Time permitting after completion of primary objective): To undertake catch comparison trials using a 600mm Square Mesh Panel (SMP) rigged at 12-15m from the cod line of the BT201. 

Procedure:

Deep Vision is a camera system developed at IMR Bergen which will film fish passing down the taper of BT201 allowing species identification and measurement to be made. It is rigged into a 4-panel section at the end of the taper of BT201. A small mesh collection codend is fitted behind the camera section.

The Deep Vision gear, mini TV equipment and scanmar instrumentation will be rigged aboard the vessel prior to sailing on 02 November. The intention will be to make for suitable grounds with good visibility in the Moray Firth close to Fraserburgh to test the Deep Vision systems while using cameras to observe the rigging and fish behaviour in the vicinity of the system.

Part 1: Deep Vision system. The preferred area of operation for obtaining clear water along with reasonable gadoid catches will be the Orkneys, while the Moray Firth will provide nephrops grounds and potentially a range of turbidities. Which area is worked first will depend on the prevailing weather conditions and decisions will be made following detailed discussions with the skipper and will take into account the working practices of the vessel.

The number of hauls made each day and their duration will be variable and depend on the grounds being fished, visibility, and catch. At the end of every haul the footage from Deep Vision will be downloaded and the catch sorted into species and measured.

There will be one scheduled port call (TBA) for change of staff, this likely to be around 8th November but exact date will be in accordance with progress.

Part 2: Catch comparison with BT201 incorporating a 600mm SMP. This will take place in areas where there has been reasonable quantities of commercial gadoids identified during the part 1. The trawl will be fished with the SMP in place alternatively covered/uncovered with 80mm diamond mesh to provide a comparison in catch rates. At the end of each haul the catch will be sorted by species and measured.

General:

There is no need for any night hauls during this survey and work patterns will be arranged around the normal working hours/practices of the vessel. The survey will end in Fraserburgh on 13 November with all staff, fishing gear and scientific equipment returning to the Marine Laboratory.


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