Marine Scotland

MRV Scotia Survey 1616S Programme

November 22, 2016 by No Comments | Category Fisheries, Marine Scotland general, Marine Scotland Science, Research Vessel Surveys

Duration: 5-14 November 2016

Fishing Gear:

  • PT160 pelagic trawl;
  • BT237 new Jackson high standing demersal trawl fully rigged with 350mm rockhopper ground gear and 200mm floats;
  • 1 Set Thyboron ‘flapper’ trawl doors; and
  • 1 set GOV polyvalent trawl doors.

Objectives:

  1. To establish a fishing protocol to fish the PT160 trawl close to the surface and in mid-water using the Thyboron ‘flapper’ trawl doors.
  2. To configure the same doors to demersal fish the BT237 trawl.
  3. As Objective 2 but to fish with the polyvalent trawl doors, used with the GOV (BT137), as a comparison.
  4. To obtain underwater observations using mini TV system, gear geometry and drag data for both trawls.

Procedures:

The fishing gear will be loaded aboard and rigged prior to the start of the survey. The PT160 trawl will be rigged on the top net drum and the BT237 trawl rigged on the lower net drum. The ‘flapper’ doors will be used first and the polyvalent doors stored on the upper castles. It should be noted the trawl doors will need to be switched over towards the end of the survey.

The main objective is to identify the optimal configuration for the new ‘flapper’ doors to fish both pelagic and demersal survey trawls during the annual herring survey.

Post departure from Aberdeen and after all safety drills have been completed, the vessel will sail to the Moray Firth. Trials will start with the pelagic gear and aim to establish the correct rigging configuration to ensure the ‘flapper’ doors operate optimally (near surface and pelagic) with the PT160 trawl. Once Objective 1 has been completed the same process will be undertaken to demersal fish the BT237 trawl (Objective 2). During the survey underwater observation will be made using a mini (self-recording) TV system to assess netting shape and opening. Gear geometry and load cell data will be collected to measure gear performance. After completion of trials with the ‘flapper’ doors and as a comparison (with GOV trawl – BT137) the BT237 trawl will be fished with the 1100kg polyvalent trawl doors (Objective 4).

Flexibility will be required as calm sea conditions are required for underwater observations and gear geometry measurement. Survey schedule and operations will be decided by Scientist-in-Charge after daily consultation with Fishing Master and Captain.


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