Seafood Harvest Methods

Ocean Wise recommendations with harvest method specified as “All Production Methods” denotes the recommendation covers all possible aquaculture production methods.

Barriers, fences, weirs, corrals, and similar fishing methods utilize a variety of materials such as branches, stakes, netting, and rocks to obstruct fish movement. These harvest methods are employed in the marine intertidal zone or in rivers or streams. They can be used to capitalize on tidal action and trap marine fish in the intertidal as the tide recedes or can be used to direct fish movement to a particular location for capture.

Species typically harvested: Salmon, eel, perch, whitefish

A method of aquaculture in which bivalves (e.g., Clams or oysters) or seaweeds are grown on the seabed.

Organisms are typically transferred from hatcheries and seeded onto the seabed to grow-out. Mature seaweeds and bivalves are later harvested by hand, rakes, or dredging.

Species typically harvested: Oysters, scallops, clams, and seaweeds

See Bottom Culture.

In enclosed bottom culture organisms are confined inside or under nets or other containment structures set on the seafloor.

See Bottom Culture.

In open bottom culture organisms are not confined under or within a containment structures and instead are grown in the open on the seafloor.

A fishing technique developed to reduce high bycatch levels within swordfish fisheries. It is composed of a free-floating buoy attached to a fishing line containing one to several baited hooks. Buoys are set in straight lines and actively monitored by fishers. When a fish strikes a baited hook it pulls the buoy out of line which signals to fishers that a fish is hooked.

Species typically harvested: Swordfish

A type of falling gear composed of a circular piece of netting with small weights sewn into its edge. The net is typically thrown by hand from a vessel near shore, or from shore to catch shoals of fish swimming near the surface.

Species typically harvested: A wide variety of fish and shrimp species

Diving comprises of gathering fish or invertebrates by hand or with simple hand implements with or without SCUBA equipment.

Species typically harvested: Sea urchins, sea cucumbers and geoduck clams

A fishing method classification based on the Food and Agriculture Organization of the United Nations International Standard Statistical Classification of Fishing Gear (ISSCFG).

Classification includes:

• Hand dredges
• Mechanical dredges
• Vessel towed dredges

All dredges are metal-framed baskets that are dragged across the ocean floor. They are equipped with large metal teeth that dig into the seabed to lift shellfish buried in the mud or sand.

This harvest method can cause significant damage to sensitive habitats and as it is an unselective gear type can result in high bycatch. Limiting the area in which dredges are used and targeting sandy, rather than hard bottoms can help to minimize their impact.

Species typically harvested: Scallops, mussels, and oysters

See Dredges.

	Small, light, handheld, metal-framed baskets or mouth frame attached to a holding bag constructed of metal rings or meshes that are dragged across the ocean floor. They are equipped with large metal teeth that dig into the seabed to lift shellfish buried in the mud or sand. Species typically harvested: Scallops, mussels, and oysters

See Dredges.

	Mechanized dredges are gear that were specifically developed to dig and wash out organisms that have buried in the seabed while harvesting machines extract organisms from the water by forced sifting or pumping. Species typically harvested: Scallops, mussels, and oysters

See Dredges.

Water power rotates large paddles and associated baskets that capture fish moving upstream. The rotation of the fish wheel funnels the live fish to a holding tank where they can be individually selected for harvest or released alive back into the river.

Species typically harvested: Salmon and trout

A fishing method classification based on the Food and Agriculture Organization of the United Nations International Standard Statistical Classification of Fishing Gear (ISSCFG).

This gear classification includes:

• Combined gillnets-trammel nets
• Drifting gillnets
• Encircling gillnets
• Fixed (staked) gillnets
• Set (achored) gillnets
• Trammel nets

All gillnets and entangling nets are panels of netting that are nearly invisible to the fish. Fish that attempt to pass through the net become entangled by their gills. They can be set in a variety of configurations using floats and/or weights to suspend the netting and can drift in the water column, be set on stakes in shallow water, or pinned to the seafloor with weights to catch demersal (bottom dwelling) species.

Gillnets and entangling nets can incur bycatch through the accidental capture of vulnerable animals including marine mammals, sea turtles, and sharks. However, these impacts can be reduced through a number of measures such as setting nets deeper in the water column to allow animals to swim over the top, or modifications to the gear such as the addition of pingers that warn passing marine mammals.

Species typically harvested: Cod, perch, salmon, trout, sardines

See Gillnets and Entangling Nets.

Panels of netting that are nearly invisible to the fish. Fish that attempt to pass through the net become entangled by their gills. Drifting gillnets consist of a single gillnet panel, or string of panels held open by floats on the upper line (head rope) and sometimes use of weights on the lower line (ground rope). The nets are marked by buoys and left to drift with the current either at the surface or at depth within the water column.

Drifting gillnets can incur bycatch through the accidental capture of vulnerable animals including marine mammals, sea turtles, and sharks. However, these impacts can be reduced through a number of measures such as setting nets deeper in the water column to allow animals to swim over the top, or modifications to the gear such as the addition of pingers that warn passing marine mammals.

Species typically harvested: Tunas, swordfish, sharks, herring, salmon, seabass

See Gillnets and Entangling Nets.

Encircling gillnets are gillnets which are set vertically in shallow waters in such a way that they encircle fish. Once fish have been encircled by the net, noise or other means are used to force the fish to entangle in the netting.

See Gillnets and Entangling Nets.

Panels of netting that are nearly invisible to the fish. Fish that attempt to pass through the net become entangled by their gills. Gillnets can be set in a variety of configurations using floats and/or weights to suspend the netting. Gillnets can drift in the water column, be set on stakes in shallow water, or pinned to the seafloor with weights to catch demersal (bottom dwelling) species.

Gillnets can incur bycatch through the accidental capture of vulnerable animals including marine mammals, sea turtles, and sharks. However, these impacts can be reduced through a number of measures such as setting nets deeper in the water column to allow animals to swim over the top, or modifications to the gear such as the addition of pingers that warn passing marine mammals.

Species typically harvested: Cod, perch, salmon, trout, sardines

See Gillnets and Entangling Nets.

Panels of netting that are nearly invisible to the fish. Fish that attempt to pass through the net become entangled by their gills.

Set gillnets are either anchored to the bottom or fixed, stretched between two or more stakes that are driven into the bottom within intertidal or freshwater habitats.

Species typically harvested: Salmon, sablefish, cod, haddock, flounder, hake

See Gillnets and Entangling Nets.

A fishing method classification based on the Food and Agriculture Organization of the United Nations International Standard Statistical Classification of Fishing Gear (ISSCFG).

Hand harvesting refers to the manual extraction of fish, invertebrate, and plant species either by hand, or using hand operated tools like wrenching gear, clamps, tongs, rakes, or spears. Hand harvesting is a selective method of fishing/farming as humans visually identify the species before harvest. This avoids the extraction of non-targeted species, and minimizes habitat damage.

Species typically harvested: Clams, barnacles, lobsters, fish, and sea urchins

A type of hook and line fishing gear where a single hook and attached line are operated without an pole or rod (handline) or with a pole or rod (pole-and-line).

Species typically harvested: Variety of finfish such as cod

A type of hook and line fishing gear where a single hook and attached line are operated without an pole or rod (handline) or with a pole or rod (pole-and-line) without the use of mechanically powered reels or drums.

Species typically harvested: Variety of finfish such as cod

Mechanized handlines and pole and lines are a type of hook and line fishing gear where a single hook and attached line (either with or without an associated pole or rod) are operated by mechanically powered reels or drums.

Targeted species: Tuna

A fishing method classification based on the Food and Agriculture Organization of the United Nations International Standard Statistical Classification of Fishing Gear (ISSCFG).

This gear classification includes:

• Handlines
• Longlines
• Pole-and-lines
• Trolling lines
• Vertical lines

All types of hook and line fishing gears use hooks baited with natural or artificial bait (lures) and suspended within the water column by fishing line.

Named for the green tint of the traditional Japanese poles used when fishing with this method, greenstick is a modified trolling method where multiple hooks and associated lures are suspended both above and below the waters surface.

Species typically harvested: Tuna

See Vertical lines.

	A jig is a type of vertical line fishing. The gear is composed of a baited or lured hook attached to a single line. The hook and line are jerked through the water in a manner that resembles a moving fish. When jigging for squid, fishing usually occurs at night and lights are used to attract the squid. Species typically harvested: Variety of finfish and squid

A fishing method classification based on the Food and Agriculture Organization of the United Nations International Standard Statistical Classification of Fishing Gear (ISSCFG).

All lift nets are composed of a net bag or horizontal net panels used in combination with bait or light to attract fish and invertebrates. Lift nets are submerged and left within the water column for a set amount of time, then retrieved to capture attracted fish or invertebrates.

Species typically harvested: A variety of small fish and squid species

See longlines.

Demersal, also known as deep-set, or set longlines are a method of longlining where fishing occurs near or on the seafloor. They can range in length from a few hundred meters in some coastal fisheries to over 50km in length in some large scale fisheries. Deep-set longlines do not have the same bycatch considerations as surface longlining.

Species typically harvested: Halibut and cod

See longlines.

Longlines supported by floats which drift in the ocean current. Drifting longlines are commonly used to catch pelagic species like tuna and swordfish.

Surface longlines are an unselective fishing method and can have large impacts on other species which are accidentally caught as bycatch (e.g. birds, juvenile fish, marine mammals, and sharks).

Longline gear can be modified to minimize these impacts through use of specially designed fishing hooks called circle hooks or the use of streamers above the water to deter seabirds.

A fishing method classification based on the Food and Agriculture Organization of the United Nations International Standard Statistical Classification of Fishing Gear (ISSCFG).

Miscellaneous Gear includes:

• Diving
• Drive-in nets
• Electric fishing
• Harpoons
• Hand implements
• Pumps
• Pushnets
• Scoopnets

Structures that contain farmed fish within open water. They can be composed of wood, net screens, or mesh which allows water to move freely into and out of the enclosure. Net pens can be enclosed only on the bottom and sides and float at the surface of the water column or be enclosed on all sides and submerged within the water column.

Net pens and cages can be problematic because the farmed species are in direct contact with the surrounding ecosystem. Waste water can affect the benthic (seafloor) habitat directly below the farms, and there is the risk that if farmed fish develop diseases and parasites, these can be passed on to wild populations. If any farmed fish escape from the pen, they can negatively affect wild populations by competing with them for food and habitat. Hybridization (interbreeding) with wild individuals is also a concern, since this could produce genetically less fit offspring and compromise the quality of the wild population. If antibiotics are used in the net pens, their open nature and direct contact with the environment makes the potential for spread of antibiotic resistance in humans a serious concern.

Species typically harvested: Salmon and trout

See net pens / cages.

Net pens or cages operated in freshwater systems such as lakes.

See net pens / cages.

Net pens or cages operated in marine (ocean) systems such as the open ocean.

Aquaculture method that uses floating rafts, bags, or suspended ropes to grow shellfish. This system makes no contact with the seafloor, and shellfish are harvested with little to no bycatch. Since shellfish are filter feeders, they offer ecosystem benefits by reducing nutrient load in the water and do not require any external feed as they extract nutrition from plankton in the seawater. This means that shellfish farming puts no pressure on wild fish stocks for feed.

Species typically harvested: Oysters, mussels, clams, and scallops

See Off-Bottom Culture.

Rope or frame aquaculture also called longline culture is a type of open-water off-bottom culture where cultured species are grown on ropes or diverse containers (e.g. baskets, stacked trays, lantern nets) suspended from anchored and buoyed surface or subsurface ropes (longlines).

Commonly culture species: Bivalve molluscs (e.g. mussels, oysters, scallops) and seaweeds (e.g. kelp). 

Ponds can be naturally occuring or man made and are relatively shallow and small bodies of fresh or saltwater used to grow fish and shellfish. This aquaculture method can vary from low-tech extensive ponds to highly sophisticated systems. Historically, aquaculture ponds have been built along coastlines, which has contributed to the destruction of mangrove forests, critical habitat for many species. Ponds can have significant impacts on the surrounding environment depending on the level of treatment water receives before it is discharged, and if farm-raised species are able to escape.

Species typically harvested: shrimp, catfish, and tilapia

See Ponds.

Extensive ponds are usually relatively small and shallow bodies of still water. They are characterized by their scale of production (yielding no more than 500 kg/ha/yr) and low production efficiency, use of natural waterbodies (e.g. lagoons, bays, embayments) and water fertilisation for nutrient provision, low initial costs and low level use of technology, and high dependence on local climate and water quality.

See Ponds.

Intensive  ponds are usually relatively small and shallow bodies of still water. They are characterized by their scale of production (up to 200 tonnes/ha/yr), production efficiency, use of man made culture systems, high initial costs and high level use of technology, and tendency towards increased independence of local climate and water quality.

See Ponds.

Semi-extensive ponds are usually relatively small and shallow bodies of still water. They are characterized by their scale of production (0.5—5 tonnes/ha/yr), use of supplemental feed, fertilizer use, stocking with wild-caught or hatchery-reared fry, the use of rainwater or tidal flow for water supply, and the presence of water exchange with the surrounding habitat.

See Ponds.

Semi-intensive ponds are usually relatively small and shallow bodies of still water. Aeration may be used to maintain water quality. Production within semi-intensive ponds requires more on the use of external sources of feed  (homemade, commercially formulated, or use of water fertilization) than semi-extensive but less so than intensive systems. These facilities also rely on hatchery-raised stock for production. 

Cages or baskets composed of a variety of materials including wood, metal, or plastic. They may have one or more entrance are are designed to attract organisms to enter (sometimes through use of bait) but make it extremely difficult or impossible for them to escape.

Pots are commonly set in rows or “strings” on the seafloor. The gear is then left to “soak” for a period of hours to days before being hauled to the surface.

Target species: e.g., Crabs, lobsters, shrimp, sablefish, octopus

Nets deployed by boat to encircle a school of fish. Once set, fishers pull the bottom of the netting like a drawstring purse, to corral fish into the center of the net which is then hauled. Depending on the species targeted, purse seines can cause varying amounts of bycatch.

Purse seines can either be unassociated (also known as “free school”) or utilize fish aggregating devices (FADs).

Unassociated purse seines or “free school” purse seines, target schooling fish without using fish aggregating devices (FADs). Floating object purse seines are purse seine nets deployed with a fish aggregating device (FAD).

Species typically targeted: Tunas, mackerel, herring, sardines, anchovies, and salmon

See Purse Seines.

Purse seines can either be unassociated (also known as “free school”) or utilize fish aggregating devices (FADs).  FADs consist of floating material which serve to attract open-ocean fish. They can be composed of anything from netting and floats, to wood, to plastic.

This method can result in high bycatch of threatened species including sharks, juvenile tunas and turtles and if composed of non-biodegradable materials can also contribute to marine waste.

Species typically targeted: Tunas, mackerel, herring, sardines, anchovies, and salmon

See Purse Seines. 

Unassociated purse seines or “free school” purse seines, target schooling fish without using fish aggregating devices (FADs). Floating object purse seines are purse seine nets deployed with a fish aggregating device (FAD). FADs consist of floating material which serve to attract open-ocean fish.  This method can result in high bycatch of threatened species including sharks, juvenile tunas and turtles.

Species typically targeted: Tunas, mackerel, herring, sardines, anchovies, salmon

See purse seines.

	Dolphin pods are sometimes used as a natural cue to aid toward areas of abundant schooling fish (called “setting on dolphins”). Once the netting has been set, encircled marine mammals cannot escape and can become entangled, injured, or stressed. When you see dolphin safe tuna, it implies that this strategy was not used. Species typically harvested: Tuna

See Raceways.

Indoor flow-through Raceways are indoor containment structures utilized in the cultivation of organisms for aquaculture. They are usually located above ground, with a long linear configuration, and have high rate of water turnover.  Water flows through each tank and the wastewater, which may contain nutrients, wastes, and/or chemicals leaves the facility, potentially impacting local wildlife and habitats. 

See Raceways.

Outdoor flow-through Raceways are outdoor containment structures utilized in the cultivation of organisms for aquaculture. They are usually located above ground, with a long linear configuration, and have high rate of water turnover.  Water flows through each tank and the wastewater, which may contain nutrients, wastes, and/or chemicals leaves the facility, potentially impacting local wildlife and habitats. 

A net bag held open by a frame which may or may not be attached to a pole. It is a hand-operated fishing gear used to scoop fish out of the water and commonly used in artisanal fisheries.

Species typically harvested: A variety of small fish and salmon

A fishing method classification based on the Food and Agriculture Organization of the United Nations International Standard Statistical Classification of Fishing Gear (ISSCFG).

All seine nets utilize a vertical panel of netting held open by floats on the upper panel and weights on the lower panel. Seine nets can be utilized in a variety of ways including from shore (e.g., beach seines) or in deep water (e.g., vessel towed seines such as pair seines or Danish seines).

See Seine Nets.

Beach seines are long nets operated from shorelines primarily by hand. The seine net has floats attached to its top side and is weighted at the bottom. This net structure keeps the net in contact with the bottom, trapping fish within the area it encloses. Since schooling or spawning fish are easily targeted by beach seines, the use of beach seines must be well-regulated in order to be sustainable.

Species typically harvested: Sardines, salmon, mullet, and pompano

See Seine Nets.

Danish seines (also known as anchor seine) is a variation on tradition seining techniques. The seine net is composed of a cone-shaped net with two long wings each attached to a fishing line and anchor.

Deployment of a Danish seine occurs much like a hitter running the bases of a baseball diamond. At home plate an anchor and fishing line are deployed. The vessel then streams a straight course to first base, all the while extending the rope into the water. It then adjusts course and aims for second base, once there the vessel “shoots” the seine net, deploying it. The vessel then traces the other half of the diamond back to home plate, returning to the anchor. The net is then hauled, herding the fish into the net’s path and capturing the fish inside.

See Seine Nets.

	Pair seines are a variation on traditional seining techniques where a single seine net (composed of a cone-shaped net with two long wings each attached to a fishing line) is set and hauled by two vessels.

Also known as integrated shrimp-mangrove pond systems, silvoculture is an alternative to traditional shrimp ponds. Shrimp are raised within naturally occurring mangrove forests or within man made ponds that are planted with mangrove trees. Farmers are often required to set aside a portion of their farming area for mangrove cultivation which may be eventually harvested as timber and replanted for subsequent harvests.

In many silvoculture farms with natural mangroves, no external feed is given to the shrimp, as they feed off the natural forest resources. Chemicals are not used, and disease is controlled by not overcrowding the shrimp.

Species typically harvested: Black tiger shrimp, whiteleg shrimp

Surrounding nets are walls of netting that are towed by a vessel to surround fish aggregations. They are generally used in surface waters. An example of a surrounding net is a purse seine.

Species typically harvested: Tunas, sardines, and other schooling fish in open waters

See Recirculating aquaculture systems.

Land based facilities that utilize water filled tanks and a continuous flow of water to farm fish and shellfish. These facilities may or may not use filtration systems to remove solid and particulate waste from wastewater and reuse and recirculate this water throughout the farm.

Species typically harvested: Rainbow trout, Arctic char, sturgeon, salmon

See Tanks.

Indoor containment structures used in the cultivation of organisms for aquaculture. They are usually located above ground and have high rate of water turnover.  Water flows through each tank and the wastewater, which may contain nutrients, wastes, and/or chemicals leaves the facility, potentially impacting local wildlife and habitats. 

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	Diagram of recirculating aquaculture tank.

See Tanks.

Outdoor containment structures used in the cultivation of organisms for aquaculture. They are usually located above ground and have high rate of water turnover.  Water flows through each tank and the wastewater, which may contain nutrients, wastes, and/or chemicals leaves the facility, potentially impacting local wildlife and habitats. 

Species typically harvested: Rainbow trout, Arctic char, sturgeon, salmon

Indoor aquaculture complex at Virginia Tech	Diagram of aquaculture tank.

A fishing method classification based on the Food and Agriculture Organization of the United Nations International Standard Statistical Classification of Fishing Gear (ISSCFG).

This fishing gear classification includes:

• Barriers, fences, weirs, and corrals
• Fyke nets,  trapnets/pound nets,  and stow nets
• Pots
• Traps

All traps are immobile enclosures composed of metal or flexible nets placed on the seafloor or lake or river bottom.

Traps can utilize escape hatches and other technologies that allow undersized or immature individuals to escape. Additionally, bycatch accidentally caught can often be released live and uninjured.

Traps are generally a sustainable way of fishing, unless they are placed in areas where the main fishing line which ties them together has the potential to entangle migrating marine mammals, or if they are placed on top of sensitive habitat.

See traps.

	Crab rings are a type of trap that are specifically designed to catch crabs. Essentially a collapsible basket on a rope, crab rings lay flat, collapsed on the seafloor. When the rope is pulled, the basket take shape and traps any crabs attracted to the bait placed within the basket.

See traps.

Pound nets, stow nets, and trapnets consist of cylindrical or cone-shaped bags of netting, or netting panels mounted on rings or held in place with stakes. They utilize leaders of netting to guide fish into the net bag.

Species typically targeted: Eels, salmon, shrimp 

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Diagram of a trap net.

A fishing method classification based on the Food and Agriculture Organization of the United Nations International Standard Statistical Classification of Fishing Gear (ISSCFG).

There are many different configurations used in trawling, but all trawls are cone-shaped nets that are towed by a boat through the water column or against the seafloor. Depending on type, a trawl net can be held open horizontally by beams, large rectangular otter boards, or by the distance between two vessels. Trawl nets are held open vertically through the use of floats or weights.

Trawl nets vary in length however industrial scale trawlers can be immense. Trawls are an efficient but unselective fishing method which can incidentally capture a variety of species including some of conservation concern (e.g., marine turtles) as the net will capture any organism it encounters that is large enough not to pass through the mesh. Technologies like turtle excluder devices and strong management can reduce bycatch and make trawling more sustainable.

You can learn more about the diverse gear types that make up the trawls classification by clicking the tabs below.

• Beam trawls
• Bottom / demersal trawls
• Megdalena – Artisinal bottom trawls
• Midwater / pelagic trawls
• Nephrops (lobster) trawls
• Otter trawls
• Pair trawls
• Shrimp trawls
• Skimmer trawls

See Trawls.

A type of bottom trawl composed of a cone shape net held open by a large horizontal metal or wood beam. Two trawl feet at the ends of the beam serve as sleds which drag across the seafloor keeping the net in contact with the bottom. Beam trawls can be configured as single nets towed by a single boat or two nets towed by a single boat.

Beam trawls are an unselective fishing method can capture large amounts of bottom-dwelling organisms as bycatch (e.g., crabs and other shellfish, starfish, etc). There is a substantially body of scientific research devoted to reducing beam trawl bycatch and improving the selectivity of this harvest method.

Species typically harvested: Flatfish and shrimp

See Trawls and bottom/ demersal trawls.

A bottom trawl specifically designed to catch nephrops lobster.

When used over certain types of bottom habitat, bottom trawls like nephrops trawls can cause destruction of physical structures such as corals and sea sponges. Impacts of bottom trawls can be minimized by modifying the nets and implementing management measures that limit designated areas that can be trawled.

Species typically harvested: Nephrops lobster

See Trawls and bottom/demersal trawls.

A type of bottom trawl that uses two large metal or wood doors (otter boards) on the edge of the net opening to hold the trawl net open as it moves over the seafloor.

When used over certain types of bottom habitat, bottom trawls can cause destruction of physical structures such as corals and sea sponges. Impacts of bottom trawls can be minimized by modifying the nets and implementing management measures that limit designated areas that can be trawled.

See Trawls and Bottom Trawls. A skimmer trawl consists of a fishing net fixed to a large L shaped frame. The nets and frames are suspended from large booms which extend from the sides of the vessel an allow the nets to be pushed through shallow, nearshore waters. Skimmer trawls are used with chained footropes an a tickler chain that stir up the seafloor and lift bottom dwelling organisms into the water column where they are trapped in the net.

When used over certain types of bottom habitat, these trawls can cause destruction of physical structures such as corals and sea sponges. Impacts of bottom trawls can be minimized by modifying the nets and implementing management measures that limit designated areas that can be trawled.

Species typically harvested: Shrimp

See Trawls and Bottom Trawls.  Beam trawls are a trawling method where the net is held open by a large horizontal beam which can range in size up to 12m.

See Trawls. Midwater trawls are towed at a variety of depths within the water column but do not contact the ocean floor. This harvest method is used to target pelagic (open water dwelling) species.

Species typically targeted: Shrimp and schooling fish (e.g., anchovies)

Animated Seafood Watch video of a mid-water trawl (Credit: Seafood Watch)

See Trawls. Pair trawling is a fishing technique where two vessels work together to tow a single trawl net either through the water column or against the sea floor.

Species targeted: Finfish and invertebrates

Trolling is a hook and line fishing method that utilizes several fishing lines with baited hooks which are towed through the water by a vessel. The movement of these lines lures fish which are landed by hand or mechanically using small winches.

Species typically targeted: Tuna and salmon

See Hooks and Lines. Trotlines are a type of hook and line composed of a setline and multiple hooks (from six to several hundred).  Hooks are set at intervals from the mainline through attachment to short individual line segments called “trots” or dropper lines.