A fishing sinker, plummet, or knoch is a

weight In science and engineering, the weight of an object is a quantity associated with the gravitational force exerted on the object by other objects in its environment, although there is some variation and debate as to the exact definition. Some sta ...

used in conjunction with a fishing lure or

hook A hook is a tool consisting of a length of material, typically metal, that contains a portion that is curved/bent back or has a deeply grooved indentation, which serves to grab, latch or in any way attach itself onto another object. The hook's d ...

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

fly fishing Fly fishing is an angling technique that uses an ultra-lightweight lure called an artificial fly, which typically mimics small invertebrates such as flying and aquatic insects to attract and catch fish. Because the mass of the fly lure is in ...

applications, or as large as several pounds (>1 kg) or considerably more for deep sea fishing. They are formed into many different shapes for diverse fishing applications. Environmental concerns surround the usage of

lead Lead () is a chemical element; it has Chemical symbol, symbol Pb (from Latin ) and atomic number 82. It is a Heavy metal (elements), heavy metal that is density, denser than most common materials. Lead is Mohs scale, soft and Ductility, malleabl ...

and other materials in fishing sinkers.

Types

Reconstruction of a prehistoric hook and sinker

A large variety of sinkers exist, whose specific use depends on the fish 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 bra.

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 stave (wood), staves and bound by wooden or metal hoops. The word vat is often used for large containers ...

egg An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the ...

sinkers are rounded and often bead-like with a narrow hole through which fishing line is threaded. These sinkers are desirable on rock or debris 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 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 Groupers are a diverse group of marine ray-finned fish in the family Epinephelidae, in the order Perciformes. Groupers were long considered a subfamily of the seabasses in Serranidae, but are now treated as distinct. Not all members of this f ...

, and

swordfish The swordfish (''Xiphias gladius''), also known as the broadbill in some countries, are large, highly migratory predatory fish characterized by a long, flat, pointed bill. They are the sole member of the Family (biology), family Xiphiidae. They ...

, among others.

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 ejected or ...

, chemical inertness (resistance to corrosion), and

density Density (volumetric mass density or specific mass) is the ratio of a substance's mass to its volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' (or ''d'') can also be u ...

. 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. Symptoms may include abdominal pain, constipation, headaches, irritability, memory problems, infertility, numbness and paresthesia, t ...

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 Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...

(under 1 oz weight),

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

, and some states in the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

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

National Parks A national park is a nature park designated for conservation (ethic), conservation purposes because of unparalleled national natural, historic, or cultural significance. It is an area of natural, semi-natural, or developed land that is protecte ...

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

Steel Steel is an alloy of iron and carbon that demonstrates improved mechanical properties compared to the pure form of iron. Due to steel's high Young's modulus, elastic modulus, Yield (engineering), yield strength, Fracture, fracture strength a ...

brass Brass is an alloy of copper and zinc, in proportions which can be varied to achieve different colours and mechanical, electrical, acoustic and chemical properties, but copper typically has the larger proportion, generally copper and zinc. I ...

, and

bismuth Bismuth is a chemical element; it has 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 nat ...

sinkers have been marketed, but anglers have not widely adopted them due to their lower density and higher cost compared to lead. Sandsinkers 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 (also called wolfram) is a chemical element; it has symbol W and atomic number 74. It is a metal found naturally on Earth almost exclusively in compounds with other elements. It was identified as a distinct element in 1781 and first ...

is now in use, especially among largemouth bass 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. Another variant of lead-free fishing weights is presented by the Czech brand UFO Sinker, which offers weights made of heavy concrete, that can be pulled out of the water using a magnet. 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. Pb-82

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 197 ...

)
Toxic Tackle
(article by Aquarium Monsters Australia)

(article by the Minnesota Pollution Control Agency)

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