A fishing sinker or knoch is a

weight In science and engineering, the weight of an object is the force acting on the object due to gravity. Some standard textbooks define weight as a vector quantity, the gravitational force acting on the object. Others define weight as a scalar qua ...

used in conjunction with a

fishing lure A fishing lure is a broad type of artificial angling baits that are replicas designed to mimic real prey animals and attract the attention of predatory fish, using appearances, flashy colors, bright reflections, movements, vibrations and/or loud ...

hook A hook is a tool consisting of a length of material, typically metal, that contains a portion that is curved or indented, such that it can be used to grab onto, connect, or otherwise attach itself onto another object. In a number of uses, one e ...

to increase its rate of sink, anchoring ability, and/or casting distance. Fishing sinkers may be as small as 1 gram for applications in shallow water, and even smaller for

fly fishing Fly fishing is an angling method that uses a light-weight fishing lure, lure—called an artificial fly—to catch fish. The fly is Casting (fishing), cast using a fly rod, Fishing reel#Fly reel, reel, and specialized Fly line, weighted line. T ...

applications, or as large as several pounds or considerably more for deep sea fishing. They are formed into nearly innumerable shapes for diverse fishing applications. Environmental concerns surround the usage of

lead Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cut, ...

and other materials in fishing sinkers.

Types

Reconstruction of a prehistoric hook and sinker

A large variety of sinkers exist which are used depending on the fish being pursued, the environment, the current and personal preference.

Pyramid sinkers

Pyramid sinkers are shaped like a pyramid and are used when it is desirable to anchor on the bottom of water bodies. They are attached to the terminal end of fishing line by loops of

brass Brass is an alloy of copper (Cu) and zinc (Zn), in proportions which can be varied to achieve different mechanical, electrical, and chemical properties. It is a substitutional alloy: atoms of the two constituents may replace each other wi ...

Barrel or egg sinkers

Barrel A barrel or cask is a hollow cylindrical container with a bulging center, longer than it is wide. They are traditionally made of wooden staves and bound by wooden or metal hoops. The word vat is often used for large containers for liquids, ...

or egg sinkers are rounded and often

bead A bead is a small, decorative object that is formed in a variety of shapes and sizes of a material such as stone, bone, shell, glass, plastic, wood, or pearl and with a small hole for threading or stringing. Beads range in size from under ...

-like with a narrow hole through which fishing line is threaded. These sinkers are desirable on rock or

debris Debris (, ) is rubble, wreckage, ruins, litter and discarded garbage/refuse/trash, scattered remains of something destroyed, or, as in geology, large rock fragments left by a melting glacier, etc. Depending on context, ''debris'' can refer to ...

covered substrates.

Split-shot sinkers

Split- shot sinkers are small and round with a split cutting halfway through the sinker. The split can be placed on a piece of fishing line and then crimped closed. This feature makes adding and removing the weights easy and quick.

Bullet sinkers

Bullet sinkers are bullet-shaped and used widely on

largemouth bass The largemouth bass (''Micropterus salmoides'') is a carnivorous freshwater gamefish in the Centrarchidae ( sunfish) family, a species of black bass native to the eastern and central United States, southeastern Canada and northern Mexico, ...

fishing for rigging plastic worms "Texas-style".

Dipsey

Dipsey sinkers are ovate or egg-shaped and are attached to the fishing line with a loop of brass wire embedded in the sinker.

Bank sinker

Bank sinkers are long and ovate and have a small hole at the top for the fishing line to thread through.

Claw sinker

A claw sinker consists of a sinker weight which is typically of round shape, and a number of metal wire spikes grouped around the sinker weight acting as barbs. Claw sinkers are used in surf fishing on sandy bottoms with strong currents, mainly to prevent the sinker from getting carried off with the current. Upon casting a claw sinker, the line is briefly tugged so that the claws will dig themselves into the sand, allowing the rig to stay in place.

Deep Drop Weight

A Deep Drop Weight is used to reach the bottom in deeper offshore fishing applications. These fishing weights are typically cylindrical in with a brass eyelet at the top for attaching to a rig. Weights for this style of sinker range from one pound to as much as fourteen pounds. Target species include Tilefish, Grouper, and Swordfish, among others.

SandSinka

A biodegradable PLA sinker used primarily for beach and estuary fishing. This product is still in development. This sinker is connected to the line in two ways. It has an eyelet on each end so as to connect to the line and fishing hook. It also has a cylindrical tube which the line passes through to allow the sinker to moves up and down the line. The sinker can be used as a float. A normal weight sinker. Extra weight for casting which removes the weight once the sinker is immersed in water. Also has a burley bucket.

Materials

An ideal material for a fishing sinker is environmentally acceptable, cheap and dense. Density is desirable as weights must be as small as possible, in order to minimize visual cues which could drive fish away from a fishing operation. In ancient times as well as sometimes today, fishing sinkers consisted of materials found ordinarily in the natural environment, such as stones, rocks, or bone. Later, lead became the material of choice for sinkers due to its low cost, ease of production and

casting Casting is a manufacturing process in which a liquid material is usually poured into a mold, which contains a hollow cavity of the desired shape, and then allowed to solidify. The solidified part is also known as a ''casting'', which is ejecte ...

, chemical inertness (resistance to corrosion), and

density Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematicall ...

. However, lead is known to cause

lead poisoning Lead poisoning, also known as plumbism and saturnism, is a type of metal poisoning caused by lead in the body. The brain is the most sensitive. Symptoms may include abdominal pain, constipation, headaches, irritability, memory problems, infertil ...

and enter the environment as a result of the inevitable occasional loss of fishing sinkers during routine fishing. Thus, most lead-based fishing sinkers have been outlawed in the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and ...

(under 1 oz weight),

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by to ...

, and some states in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

. Lead based fishing sinkers are banned in all of US and Canadian

National Parks A national park is a natural park in use for conservation purposes, created and protected by national governments. Often it is a reserve of natural, semi-natural, or developed land that a sovereign state declares or owns. Although individua ...

. These bans have motivated the use of various other materials in sinkers.

Steel Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistan ...

, and

bismuth Bismuth is a chemical element with the symbol Bi and atomic number 83. It is a post-transition metal and one of the pnictogens, with chemical properties resembling its lighter group 15 siblings arsenic and antimony. Elemental bismuth occurs ...

sinkers have been marketed, but anglers have not widely adopted them due to their lower density and higher cost compared to lead.

Sandsinker SandSinka is a lead-free fishing sinker made from biodegradable plastics that is filled with burley or sand or both. This sinker can be used as a float. A standard sinker. A sinker that allows extra weight to be on the line for casting, which will ...

s have also been developed, using sand as weight. However, sand has a comparably low density to that of lead and makes a poor replacement.

Tungsten Tungsten, or wolfram, is a chemical element with the symbol W and atomic number 74. Tungsten is a rare metal found naturally on Earth almost exclusively as compounds with other elements. It was identified as a new element in 1781 and first isol ...

is now in use, especially among

anglers. Although several times costlier than lead, tungsten is just under twice as dense as lead and thus found desirable. The environmental effects of tungsten, however, are essentially unknown. More recently, terminal tackle manufacturers are experimenting with high density composite resins. These materials present a non-toxic alternative to lead sinkers at a lower monetary cost than alternative metallic sinkers.

References

Efforts to ban lead in fishing tackle
Retrieved 8 April 2011. MPCA Home > Sustainability > Reduce Reuse Recycle > Nontoxic Tackle: Let's get the lead out!
Strigul, Nikolay, Agamemnon Koutsospyros, Per Arienti, Christos Christodoulatos, Dimitris Dermatas, and Washington Braida. 2005. Effects of tungsten on environmental systems. Chemosphere 61, no. 2 (October): 248-258. .

External links

(from

The Straight Dope "The Straight Dope" was a question-and-answer newspaper column written under the pseudonym Cecil Adams. Contributions were made by multiple authors, and it was illustrated (also pseudonymously) by Slug Signorino. It was first published in 1973 in ...

)
Toxic Tackle
(article by Aquarium Monsters Australia)

(article by the Minnesota Pollution Control Agency)

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