Elasmobranch-Repelling Magnets and Methods of Use

a technology of magnets and branch, applied in the field of elasmobranchrepelling magnets and methods of use, can solve the problems of affecting fishing operations, real threat to several shark species, and no return on investment for fishing operations

Inactive Publication Date: 2009-02-12
STROUD ERIC MATTHEW
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0012]According to a non-limiting embodiment of the present invention, an apparatus for repelling elasmobranchs is provided comprising a high-pull-force magnet. Preferably, the high-pull-force magnet is a permanent magnet. More preferably, the high-pull-force magnet is a neodymium-iron-boride magnet. According to a non-limiting embodiment of the invention, the high-pull-force magnet may have a nickel coating to protect the magnet from corrosion. High-pull-force magnets in accordance with the present invention may have a shape of a cylinder, a cone, a circle, a cube, a disk, a bar, a sphere, a plate, a rod, a ring, a tube, a stick, a block or other shape. In a non-limiting embodiment of the invention, a high-pull-force magnet may have a hollow portion. In a non-limiting embodiment of the invention, a plurality of high-pull-force magnets may be arranged together in a ring. In another non-limiting embodiment of the invention, an apparatus is provided with a high-pull-force magnet that is capable of spinning.

Problems solved by technology

Elasmobranchs represent a significant problem in the commercial fishing industry.
Elasmobranchs are often inadvertently caught on fishing hooks and tackle directed at other more commercially valuable kinds of fish.
This loss of life has resulted in a real threat to several shark species.
Further, when elasmobranchs are caught as by-catch, fishing operations receive no return on their investment since the shark is caught on a hook that might have otherwise brought in a marketable fish.
Additionally, the fishing tackle on which a shark is caught often must be cut loose for the safety of those working on the fishing vessel causing a loss of both equipment and time.
Longlining is a commercial fishing method that suffers significant losses from shark by-catch.
The longline hooks, however, are not selective and elasmobranchs are sometimes caught in greater numbers than the intended catch.
The result is great loss of life in elasmobranchs and significant financial losses in the longline industry.
Elasmobranchs cause additional losses in the longline fishing industry by scavenging marketable fish caught on longlines before the fish may be retrieved for processing.
Elasmobranchs also represent a problem in the commercial trawling industry.
Elasmobranchs cause significant losses for trawlers because they scavenge fish caught in trawl nets before they are retrieved for processing.
As such, valuable fish are often lost to shark predation.
Also, sharks often tear holes in the nets, resulting in partial or complete loss of catch and significant repair costs.
Nevertheless, no commercially effective repellent has yet to be made available for reducing shark by-catch in the commercial fishing industry or for reducing loss of valuable fish or fishing tackle to shark predation.
Further, Applicant is unaware of any consideration in the art of the use of magnets to repel elasmobranchs to limit by-catch and other losses from elasmobranchs.
No effective repellent has yet to be marketed for limiting the risk of shark attacks faced by humans exposed to elasmobranchs.
None of these procedures proved satisfactory in preventing shark attacks.
As such, the long felt need for an effective repellent has not been satisfied.

Method used

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  • Elasmobranch-Repelling Magnets and Methods of Use
  • Elasmobranch-Repelling Magnets and Methods of Use
  • Elasmobranch-Repelling Magnets and Methods of Use

Examples

Experimental program
Comparison scheme
Effect test

example 1

Pull Force of High-Pull-Force Magnets

[0098]Some of the high-pull-force magnets that have been used in examples in this application are listed below in Table 1 with calculation of the pull force of the respective high-pull-force magnets based on the geometry, size, grade and nominal strength (conservative BR) of the high-pull-force magnet.

TABLE 1ConservativePull ForceGeometrySizeGradeBr (Gauss)(pounds)Puck4″× 1.5″N3813000521magnetBar6″× 2″× 0.5″N4813800191.31Hollow1″× 1″ with 3 / 16″N421320072.75cylinderhollow center2 stacked0.472″× 1.97″×N501410046.7hollow0.24″ hollowcylinderscenterCube1″× 1″× 1″N4813800110.5longlines

[0099]Pull force is descriptive of the attractiveness of a magnet to a steel flat surface. A shark is not a magnetic steel surface, but it does have a surface (likely the ampullae of Lorenzini) that interacts with the magnetic field of the magnet. As such, pull force is an appropriate method for measuring interaction of an elasmobranch with a magnetic field.

example 2

High-Pull-Force Magnets as Repellents on Longlines

[0100]The following example demonstrates the elasmobranch repellent activity of high-pull-force magnets of greater than about 150 pounds of pull force on long lines. High-pull-force magnet treatments were evaluated on one demersal longline located in the middle of a large lagoon. Adjacent longlines in the same lagoon produced large shark catch (generally greater than two sharks over the 15 hooks on a line).

[0101]Seven hooks on a demersal longline of about 1000 feet were treated with 2″×0.25″×2″ NdFeB N48 magnets (nominal force 14,000 gauss; pull force about 161 pounds). The high-pull-force magnets were secured at even-numbered hooks on the longline, directly above the eye of the hook and strapped to the gangion leader with black vinyl electrical tape. All hooks received bait. If the bait was lost during the experiment, the hook was re-baited while the high-pull-force magnets were not removed or replaced; only the bait was exchanged.

[...

example 3

High-Pull-Force Magnets as Repellents on Longlines

[0103]The following example demonstrates the elasmobranch repellent activity of high-pull-force magnets of greater than 50 pounds of pull force on long lines. A first demersal longline with eight hook sets was baited with barracuda flesh and placed in open water. No high-pull-force magnets were placed on the hooks. Five sharks were captured on the longline over 24 hours representing 5 separate shark species ranging in size from 97 cm to 240 cm. See Table 3.

TABLE 3HookSpecies11. Tiger (F), 235 cm2. Nurse (F) 231 cm3. Sharpnose (F), 97 cm234Nurse 240 cm567891011121314Blacknose 115 cm15

[0104]A second demersal longline with fifteen hook sets was baited with squid and placed in the same position in open water as the first demersal longline discussed above for 67 hours. The trial with the second demersal longline was run three months after the trial with the first demersal longline. Seven of the fifteen hooks were treated with 1″×1″×1″ neo...

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PUM

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Abstract

Devices and methods are disclosed for repelling elasmobranchs with high-pull-force magnets, including devices and methods for reducing by-catch in commercial fisheries and protecting humans from attacks by elasmobranchs.

Description

[0001]This invention relates generally to high-pull-force magnets for repelling elasmobranchs and methods of using high-pull-force magnets to repel elasmobranchs.BACKGROUND OF THE INVENTION[0002]Elasmobranchs represent a significant problem in the commercial fishing industry. Elasmobranchs are often inadvertently caught on fishing hooks and tackle directed at other more commercially valuable kinds of fish. This inadvertent catching of elasmobranchs (or other non-valued fish) is called “by-catch.” As many as 100 million elasmobranchs are killed each year as by-catch. This loss of life has resulted in a real threat to several shark species. Currently, as many as 80 species of shark are considered threatened with extinction.[0003]Further, when elasmobranchs are caught as by-catch, fishing operations receive no return on their investment since the shark is caught on a hook that might have otherwise brought in a marketable fish. Additionally, the fishing tackle on which a shark is caught...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): A01K99/00A01K83/00A01K91/00B63B35/79B63B22/00A41D7/00A44C5/00B63C11/02A01M29/24
CPCA01K75/00A01K79/02A01M29/24A01K91/18A01K95/00A01K83/00A01K99/00E02B1/006B63B32/40H01F7/0231
Inventor STROUD, ERIC MATTHEW
Owner STROUD ERIC MATTHEW
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