Trolling (fishing)

[4] A downrigger consists of a one or two metre horizontal pole which supports a weight, typically about 3 kg (6.6 lb) of lead, on a steel cable.

For example, man-made reservoirs can contain submerged trees and other structures beneath the surface which downriggers can snag.

[citation needed] "Paravanes" (underwater kites) are sometimes used as depth controlling devices,[6] particularly in commercial tuna fishing operations.

There are many inventive spreader designs, such as devices which cause the baited hooks or lures to move in helical patterns, in a sophisticated emulation of the schooling behaviour of a group of fish.

Inline boards are attached directly to the fishing line and a spring tension clip that releases upon setting or tripping the planer board so it slides down the fishing line to a swivel tied several feet in front of the lure.

[11][12][13] To be effective, trolling baits and lures must have the visual ability to attract fish and intrigue them with the way they move through the water.

[14] Most trolling lures are designed to look and behave like dying, injured, or fast moving fish.

Their purpose is to function as teasers which attract a school of fish closer to the lures that do have hooks.

Kayaks fitted with a deck-mounted bracket for holding a rod can be paddled to troll effectively for salmon.

[18] In marine environments, trolling is used in big-game fishing to catch large offshore or open-water species such as tuna and marlin.

Typically, an umbrella rig consists of four plastic neon green lures with a lead dragging behind.

Trollers range from small open boats to large refrigerated vessels 30 meters long.

With properly designed vessels, trolling is an economical and efficient way of catching tuna, mackerel and other pelagic fish swimming close to the surface.

Purpose-built trollers are usually equipped with two or four trolling booms raised and lowered by topping lifts, held in position by adjustable stays.

[22][23] Commercial trolling for tuna is more successful near offshore banks than in open water areas, and is also enhanced in the vicinity of a fish aggregation device (FAD).

[24] Historically, in Alaska, hand hook and line trolling were used commercially to catch king and silver salmon in salt water.

This method required minimal gear-boat, lines and hooks—and was used to catch fish that were still feeding in open water before returning to spawn.

Trolling was very successful in southeast Alaska and historically the catch was used by the fresh and mild-cured fish packing industries.