Long line

Long lining can be used to target both pelagic and demersal fish with the lines being rigged and set at a position in the water column to suit the particular species.

A basic long line consists of a long length of line, light rope or more common now is heavy nylon monofilament, the ‘main line’, this can be many miles in length depending on the fishery. To this main line, multiple branch lines with baited hooks on (snoods) are attached at regular intervals. This rig is set either on the seabed (demersal) or in midwater (pelagic) with a dhan bouy at either end, and allowed to fish for a set period.

Demersal longlining is seen as an environmentally friendly method of fishing, being good for size and species selectivity with minimum by-catch. There will be some seabed impact from the anchors at each end of the gear but this will be minimum and only when the gear is hauled. There may be problems with seabirds taking the baited hooks that are still close to the surface as  the gear is being shot but this can be almost eliminated by using bird scaring lines and shooting the gear from a ‘moon pool’ as some of the modern long line vessels do.

Although pelagic long lining, due to the various gear and hook configurations used is considered as highly selective for the larger pelagic fish there has been concern in certain fisheries about the numbers of seabirds, turtles and marine mammals that are getting caught or entangled by pelagic long lines. This problem of by-catch has been addressed in some areas with the adopting of bird scaring lines towed behind the vessel (tori lines) weighted lines to ensure they sink quickly below the depth of the seabirds and several other concepts to reduce accidental capture of seabirds.

By taking into consideration other characteristics of the gear, such as the time of the year, the depth the lines is set to, the soak time, the type and size of bait and the hook type, most fisheries have made considerable improvements in the reducing the incidental bycatch of turtles, seabirds, and other large pelagic fish.

Catching fish on hook and line can be traced back to early days when hooks were fashioned out of bone and used line from any twisted strands. The use of multiple hooks on one line (long line) probably did not start to come into its own until the late 1800s when the construction of hooks became more mechanised. The next major step would have been in 1950 - 1970 when automated line systems were introduced to bait and shoot haul and stow the lines.

Long lining can be used to target both pelagic and demersal fish with the lines being rigged and set at a position in the water column to suit the particular species. A basic long line consists of a long length of line, light rope or more common now is heavy nylon monofilament, with multiple branch lines with hooks on (snoods) be attached at regular intervals. On smaller inshore vessels, baiting and handling the gear by hand, they may use lines that are only a few hundred metres long with a few hundred hooks attached. The larger ocean going long line vessel with modern automatic baiting and hauling systems will shoot lines that are several miles long with many thousands of hooks on. As in most fishing methods the amount of gear used is dictated by the size of the vessel.

As with most static gear the end of the line is shot away with an anchor to fix it to the seabed and a bouy to mark where it is and aid retrieval. The anchor and bouy are shot away first then as the boat steams forward the line and baited hooks is paid out over the stern. The speed at which the vessel shoots its gear depends greatly on the set up they have on board. The smaller inshore boats pre baiting the hooks and shooting out of plastic tubs on the deck will have to shoot fairly slowly, the large auto liners where the hooks are automatically baited as the line is shot from racks on deck will be able to shoot at speeds in excess of 6 knots, or about 5 hooks per second.

The line is then allowed to fish for a certain length of time, often over one change of tide or a full 24 hour period. It is hauled using a line hauler and the fish are unhooked and passed over for processing. On the large auto line vessels the line and hooks will lead straight onto the hook storage cassettes and in preparation for baiting and shooting away again. On the smaller vessels it will be fed into a tub and probably taken ashore to be baited by hand.

There are two main types of long line fishing, demersal long line where the lines are set on the seabed, or very close to it, and pelagic or midwater long lines where the lines are set at a specific position in the water column to suit the depth of water where the fishermen think the target species will be feeding at.

Demersal long line is used to target the bottom feeding fish in particular cod, haddock, ling and some flatfish. It can be very size selective by variation in hook size and the species can be regulated by the skippers experience in where he shoots his gear, what depth of water and what bait is used. It is accepted as a very environmentally friendly method of fishing with very little bycatch and discards.

Nowadays in the UK,  long line fishing is operated on a small scale by on a few inshore vessels in different parts of the country, usually on a seasonal basis. Most of the larger demersal long line vessels that supply fish into UK are based in Norway, Iceland etc. However demersal long line in some form is used by fishermen throughout the world.

Pelagic long lining is undertaken worldwide to some degree but tends to be concentrated in tropical regions where there are concentrations of large pelagic species. The main target species are various species of tuna, billfish and swordfish.

The gear is very similar to the demersal longlines but they are not anchored but allowed to drift below the surface being marked by large dhan flags at each end and at regular intervals along the line. In pelagic lining the snoods are usually spaced further apart to suit the widely dispersed nature of the target species. The line is suspended below the surface by short lines with floats attached spaced out along the main line. The length of these lines is set to hang the baited line at a suitable depth for the target species. There will be a certain amount of sag between the float lines but this allows the bait to be fished at slightly different depths.

More information can be found on the FAO website.