GEAR AND SELECTIVITY DEVICES

The Icelandic fishing fleet is technologically advanced and uses a variety of fishing techniques and gear. Their range of fishing gear includes handline, longline, gillnets, Danish seine, groundfish bottom trawl, pelagic or midwater trawl, nephrops trawl, herring seine, capelin seine, capelin pelagic trawl, shrimp trawl, ocean quahog ploughs and whelk traps.

The landed catch and catch value varies enormously from one type of gear to another. This is summarised for the main types of gear in the following table.

Gear	species	quantity in tonnes 2006	value in million ISK 2006
Purse seine	pelagics	290,000	4,400
Bottom trawl	groundfish, flatfish	286,000	34,400
Pelagic trawl	pelagics, groundfish	530,000	11,300
Gillnets	groundfish	31,000	4,300
Longline	groundfish	130,000	14,400
Danish seine	groundfish, flatfish	37,000	4,700
Handline	groundfish	9,000	1,100
Shrimp trawl	coldwater shrimp	3,000	300
Nephrops trawl	Norway lobster, groundfish	5,000	900

Shrimp trawl hauled on board.

In terms of individual fish stocks, such as the most important groundfish stocks, the following rounded figures in thousands of tonnes were the landings by different gear in 2006.

Trawls
Trawls are funnel shaped bags of nets that are dragged (trawled) horizontally in the ocean. They are either bottom trawls or midwater trawls depending on whether they are trawled along the ocean floor or in mid water. The trawls are classified further by the type of fisheries that they have been adapted to, such as bottom trawls for the groundfish, shrimp and nephrops fisheries, mid water trawls for the oceanic redfish fisheries and pelagic trawls for the capelin and blue whiting fisheries. Pelagic trawls are being developed further and are increasingly used also in the herring fisheries.

Sketch of a bottom trawl

Bottom trawl
The bottom trawl is amongst the most important gear used in the Icelandic fisheries and has been adapted to suit the various conditions of different fisheries. It is used at various depths, ranging from 80 m to 1500 m. In the groundfish fisheries the minimum mesh size is 135 mm and selectivity devices are also required in some fishing areas. In the shrimp fisheries the minimum mesh size is 45 mm in the wings and towards the square but 36 mm beyond that. In the nephrops fishery the requirements are a minimum mesh size of 135 mm in the square and 80 mm in other sections of the trawl.

The picture shows the relative size of a bottom trawl in the groundfish fisheries. The trawl extends 200 m from the trawl doors to the cod end and is being trawled at 1,500 m (900 fathoms) by the stern trawler.

The fish species most often caught by bottom trawl are cod, coastal redfish, haddock, saithe and Greenland halibut but trawls are also used in the plaice, catfish, ling, tusk and silver smelt fisheries.

Problems of a considerable by-catch of small fry and immature fish may arise from time to time and from one area to another in spite of the regulations for minimum mesh size. In order to overcome this, a range of selectivity devices has been developed that exclude the by-catch from the square part of the trawl. The devices are usually grids that will exclude the by-catch which may be either larger than the target species in case of immature small fish in the shrimp fisheries or it may be smaller than the target species such as small fry and immature shrimp in the shrimp fisheries.

Shrimp trawls are usually larger than groundfish trawls but they have a smaller mesh size and the wires leading from the trawl to the trawl doors are much shorter. Trawling is slow in the shrimp fisheries and the trawl may be out for 10-12 hours in the deepwater fisheries. Sorting grids are obligatory in the deepwater shrimp fisheries, primarily in order to avoid a by-catch of small redfish and Greenland halibut.

In recent years, the use of twin-trawls has become common in the shrimp fisheries. The advantage of using two smaller trawls side by side is an improvement in catchability relative to the machine power. Twin-trawls are also common in the nephrops fishery.

Midwater (Pelagic) trawl
Pelagic trawl is very important in the oceanic redfish fishery and is also used to a large extent in the capelin, herring and blue whiting fisheries. In its present use it is a very large type of fishing gear and commonly referred to also as a "gloria trawl". It operates without touching the bottom and is frequently trawled at depths of a few hundred meters in the redfish fishery. The minimum mesh size is 135 -155 mm depending on fishing area.

The picture shows the relative size of a pelagic trawl in the redfish fisheries.

Fishing with mid water trawl

The picture shows the relative size of a pelagic trawl in the oceanic redfish fishery. Fully extended, the opening of the trawl may be 23,000 square meters which equals roughly the size of five football fields.

A recent development, especially in the blue whiting fisheriesis, is for two vessels to share one trawl and divide the catch. 

Gillnets
Gillnets are placed on the ocean floor and have been adapted to many different fisheries, including cod, haddock, lumpfish, plaice and the trout fisheries. They have different mesh sizes, vary in size and are made from different materials. Fishing is based on the fish swimming into the net and getting entangled by the gills. The nets are rectangular and kept vertical by floaters on top and lead-weights at the bottom.

Gillnets are used extensively in cod fishing, especially during the late winter season. Minimum mesh size is 139.7 mm (5 1/2 inches) and maximum mesh size is 203.8 mm (8 inches) in most areas. The nets are about 50 m long. A few nets are tied together and a few such units placed by each ship. The nets are left for one night and preferably not longer since otherwise quality will suffer. Bad weather may, however, delay the nets being attended to and the fish being brought ashore for processing.

Gillnets for haddock are similar to the nets used for cod, but they have a slightly smaller mesh of 140-150 mm. Gillnets are only used in the haddock fisheries in South and the Southwest Iceland.

Gillnets

Purse seine
Purse seine is the largest fishing gear used in Icelandic waters as regards weight and net opening. About two thirds of the total Icelandic catch is fished by purse seiners, the largest quantity being capelin which is mainly used for fishmeal and oil processing.

Purse seine is a circular netting fence, which is placed around a school of pelagic fish. Floaters will kept the top edge of the net on the ocean surface while lead pieces will weigh the lower edge down. A wire is threaded through metal hoops at the lower edge and on pulling this wire the net will be closed around the fish within. The circumference of the net is gradually decreased until the catch has been collected, often in a dense mass. The fish is then pumped on board.

Sketch of a purse seiner fishing

Danish seine
Danish seine is used chiefly in the cod and flatfish fisheries near the shore where the sea bottom is sandy or made of clay. About 40% of flatfish landings are caught by Danish seine, including almost all of the dab catch and the long rough dab catch and about two thirds of the plaice catch. It is used in the fisheries all around Iceland and most often at depths of 40-60 m. Danish seine is somewhat similar to a small trawl but it is simpler in construction. It has neither trawl doors nor trawl wires, but the wings, square and funnel shaped trawl-end work on principles that are similar to the larger bottom trawls.

Minimum mesh size for Danish seine is 135 -155 mm depending on fishing areas but in the witch and lemon sole fisheries 120 mm mesh is allowed subject to a selectivity device also being used.

Longline and handline
The handline is the oldest of fishing gear used in Iceland although only the hook would be recognised by the earliest users. In recent years, computerised reels have been taken into use by most boats and they have made the fishery easier and more efficient. The reels are attached to the ship's side. The line is often 50-200 m long with a 6-8 m extension of fine twine containing the hooks. The hooks are often 10 cm long containing artificial bait. The line is let out and moved up and down by the automatic reel. It is then drawn in when the reel senses the set minimum weight of fish on the line. Handlines are mostly used by the small open boats of less than 6 grt. capacity.

The longline has been developed from the handline and is a much more efficient gear. It is used mostly in the cod, haddock, catfish, ling and tusk fisheries. It may be as long as 20 km and have up to 16,000 hooks. The bait is most often herring, capelin or squid pieces since artificial bait has been found to give poor results. The bait is often placed on the hooks using special baiting machines on board.

Hook and line fishing using automatic reels.