Scots pair trawlers equipment

5.4 Fishing gear

The Scots pair trawlers fished a variety of semi-pelagic trawls selected according to the length and horsepower of the vessels towing them. The net manufacturers describe the overall size of the trawl by the circumference of the net mouth, which ranges from 600m to 1400m in nets up to 500 m long. In order to minimise the drag created by such a large net, the meshes are graded, decreasing in size from 16 m (stretched mesh) at the mouth of the net to an 80 mm mesh codend, although 100 mm is occasionally used. The larger meshes near the net mouth serve to herd fish into the codend, as well as offering little water resistance. The favoured semi-pelagic bass trawls are constructed by French manufacturers Le Drezen and currently cost approximately £35,000 for the 950 m circumference model. Some fishermen prefer to buy second-hand bass trawls or choose to modify whitefish nets to reduce expenses.

5.5 Electronics

All UK vessels were equipped with both high and low frequency fishfinders (colour echo-sounders). In addition, many vessels had fishfinders capable of scanning a 2000 m radius around them, which enables them to detect any shoals of fish they are approaching and’ steer the vessels and net to encompass the shoal.

5.6 Fishing method

The gear is fished on 200-300 m of 22 mm warp in areas with a depth range of 50-100 m. Bass tended to be found in the top half of the water column. The net is capable of opening from seabed to the surface, but it is towed several fathoms clear of the bottom to avoid damage. The head-rope of the net is supported by four large buoys, 1.5 m in diameter, though a series of smaller 30 cm intermediate floats may also be used to ensure the head-rope is held on the surface. The foot-rope of the net is weighted with two clumps of chain (Larsen weights) each weighing approximately 500 kg. The nets are towed with the direction of the tide at 3.5-4.0 knots by Scottish vessels and up to 5.0 knots by the French fleet. When the warps are at full extension, the vessels steam parallel to each other approximately 350 m apart. Fishermen assume that fish which pass between the two vessels would enter the net.

Nets can be towed using a double or single warp system. The former method is practised by the larger UK pair teams and has the advantage that the depth of the net can be adjusted without altering the towing speed. The net can be fished deeper by extending the warp connected to the foot-rope or shallower by shortening the warp if shallow ground or obstacles are encountered. The second technique requires the use of two single warps, a method used by the smaller Scottish vessels and the majority of the French fleet. The depth of nets used in this manner can only be adjusted by altering the vessels’ towing speed.

Catches were brought aboard by use of deck cranes, which on the larger vessels had a maximum loading of 2 t. With large catches, the cod-end would be brought in with a series of 2 t lifts.

5.7 Effort

When at sea, the vessels fish 24 hours a day. Each tow lasts for 6 - 8 hours, with 1 hour between each to haul and shoot; therefore, the net is actually fishing for 21 hours a day.