U.S. patent application number 11/800545 was filed with the patent office on 2007-11-08 for elasmobranch-repelling electropositive metals and methods of use.
Invention is credited to Eric Matthew Stroud.
Application Number | 20070256623 11/800545 |
Document ID | / |
Family ID | 38660072 |
Filed Date | 2007-11-08 |
United States Patent
Application |
20070256623 |
Kind Code |
A1 |
Stroud; Eric Matthew |
November 8, 2007 |
Elasmobranch-repelling electropositive metals and methods of
use
Abstract
Devices and methods are disclosed for repelling elasmobranchs
with electropositive metals, including apparatuses and methods for
reducing by-catch in commercial fisheries and protecting humans
from attacks by elasmobranchs.
Inventors: |
Stroud; Eric Matthew; (Oak
Ridge, NJ) |
Correspondence
Address: |
ERIC M. STROUD
146 NOTCH ROAD
OAK RIDGE
NJ
07438
US
|
Family ID: |
38660072 |
Appl. No.: |
11/800545 |
Filed: |
May 7, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60798504 |
May 8, 2006 |
|
|
|
Current U.S.
Class: |
116/22A ; 43/124;
43/43.16 |
Current CPC
Class: |
A01K 83/00 20130101;
A01K 97/00 20130101; B63B 32/70 20200201; A01K 91/18 20130101; A01K
79/02 20130101; A01M 29/24 20130101; A01K 91/06 20130101; B63C
11/02 20130101 |
Class at
Publication: |
116/022.00A ;
043/043.16; 043/124 |
International
Class: |
A01M 29/00 20060101
A01M029/00; A01K 83/00 20060101 A01K083/00; A01M 1/24 20060101
A01M001/24 |
Claims
1. An apparatus for repelling an elasmobranch comprising an
electropositive metal.
2. The apparatus of claim 1 wherein said electropositive metal is
selected from the group consisting of Lanthanum, Cerium,
Praseodymium, Neodymium, Samarium, Europium, Gadolinium, Terbium,
Dysprosium, Holmium, Erbium, Thulium, Ytterbium, Lutetium, Yttrium,
Scandium, Magnesium, Calcium, Strontium, Lithium, Cerium
Mischmetal, Neodymium-Praseodymium Mischmetal, Ferrocerium,
Lanthanum Mischmetal, separately or in combination.
3. The apparatus of claim 1 wherein the electropositive metal has 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 a
tapered cone.
4. The apparatus of claim 1 wherein the electropositive metal
comprises a hollow portion.
5. The apparatus of claim 1 wherein a plurality of electropositive
metals are arranged together in a ring.
6. The apparatus of claim 1 wherein the electropositive metal is
capable of spinning.
7. The apparatus of claim 1 wherein the electropositive metal has a
revised Pauling electronegativity less than 1.32.
8. The apparatus of claim 1 wherein the electropositive metal has a
cathode half-cell standard electrode potential greater than 2.00
volts in aqueous solution.
9. An apparatus comprising an electropositive metal and a fish
hook.
10. The apparatus of claim 9 further comprising fishing tackle.
11. The apparatus of claim 10 wherein the fishing tackle is
selected from the group consisting of a longline, a mainline, a
gangion, a lead, a weight, a buoy, a net, or any combination
thereof.
12. The apparatus of claim 11 wherein the electropositive metal has
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 a
tapered cone and is located in close proximity to the fish
hook.
13. A longline comprising an electropositive metal.
14. A surfboard comprising an electropositive metal.
15. A buoy comprising an electropositive metal.
16. A swim suit comprising an electropositive metal.
17. A bracelet comprising an electropositive metal.
18. Dive equipment comprising an electropositive metal.
19. A method of using an electromotive force to repel an
elasmobranch comprising attaching an electropositive metal to
fishing tackle.
20. The method of claim 19 wherein the fishing tackle is selected
from the group consisting of a hook, a longline, a mainline, a
gangion, a lead, a weight, a buoy, a net or any combination
thereof.
21. A method of using an electromotive force to repel an
elasmobranch comprising attaching an electropositive metal to a
human body or to clothing or accessory associated with a human
body.
22. The method of claim 21 wherein the electropositive metal is a
bracelet attached to a human ankle or wrist.
Description
INTRODUCTION
[0001] This invention relates generally to electropositive metals
for repelling elasmobranchs and methods of using electropositive
metals 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 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
often must be cut loose for the safety of those working on the
fishing vessel causing a loss of both equipment and time.
[0004] Longlining is a commercial fishing method that suffers
significant losses from shark by-catch. Longlining uses multiple
baited individual fish hooks with leaders strung at intervals along
an often very long (2-3 miles) main fishing line. Longline fishing
operations routinely target swordfish and tuna. 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.
[0005] Elasmobranchs also represent a problem in the commercial
trawling industry. Trawling is a commercial fishing method that
catches fish in nets. Elasmobranchs cause significant losses for
trawlers because they scavenging 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.
[0006] There has been a long-felt need for methods and devices to
deter elasmobranchs from commercial fishing lines and nets.
Attempts in the middle of the twentieth century were made to
protect trawl nets with electric discharge devices (Nelson, "Shark
Attack and Repellency Research: An Overview," Shark Repellents from
the Sea ed. Bernhard Zahuranec (1983) at pg .20). 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 electropositive metals to repel elasmobranchs
to limit by-catch and other losses from elasmobranchs.
[0007] An effective shark repellent would not only be valuable to
the fishing industry but also would be valuable for protecting
humans from shark attacks. No effective repellent has yet to be
marketed for limiting the risk of shark attacks faced by humans
exposed to elasmobranchs. Over the last 50 years antishark measures
employed to protect humans from shark have included electrical
repellent devices (Gilbert & Springer 1963, Gilbert &
Gilbert 1973), acoustical playbacks (Myrberg et al. 1978, Klimley
& Myrberg 1979), visual devices (Doak 1974) and chemical
repellents (Tuve 1963, Clark 1974, Gruber & Zlotkin 1982). None
of these procedures proved satisfactory in preventing shark
attacks. (Sisneros (2001)). As such, the long felt need for an
effective repellent had not been satisfied.
[0008] Researchers have historically used several bio-assays to
determine if a repellent evokes a flight response in shark. One
such bio-assay measures the effect of a repellent on a shark that
is immobilized in "tonic immobility." Tonic immobility is a state
of paralysis that typically occurs when a shark is subject to
inversion of its body along the longitudinal axis. This state is
called "tonic," and the shark can remain in this state for up to 15
minutes thereby allowing researchers to observe effects of
repellents. After behavioral controls are established, an object or
substance that has a repelling effect will awaken a shark from a
tonic state. Researchers can quantify the strength of a repellent
effect from these studies.
BRIEF SUMMARY OF THE INVENTION
[0009] The applicant has discovered that an electropositive metal
is an effective elasmobranch repellent useful in limiting by-catch
as well as protecting humans. Electropositive metals, particularly
the Lanthanide metals, known or hereinafter developed, that are of
sufficient electropositivity to repel elasmobranchs are acceptable
in aspects of the present invention.
[0010] According to a non-limiting embodiment of the present
invention, an apparatus for repelling elasmobranchs is provided
comprising an electropositive metal. Preferably, the
electropositive metal is a Lanthanide metal. More preferably, the
electropositive metal is a Mischmetal. Electropositive metals 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 or a
block.
[0011] Electropositive metals of the present invention preferably
have a revised Pauling electronegativity of less then 1.32. In a
non-limiting embodiment, an electropositive metal has a cathode
half-cell standard electrode potential greater then 1.9 volts in
aqueous solution. In a non-limiting embodiment, the electropositive
metal is a Lanthanide metal, a Mischmetal, an Alkaline Earth metal,
an Alkali metal, or a Group 3 metal on the periodic table.
[0012] According to a first non-limiting aspect of the present
invention, an apparatus is provided comprising an electropositive
metal and a buoy, a barge, a net, fishing tackle or any combination
thereof. Fishing tackle may comprise a longline, a main line, a
gangion, a branchline, a weight, a buoy, a net, or any combination
thereof.
[0013] According to a second non-limiting aspect of the present
invention, an apparatus is provided comprising an electropositive
metal and a fish hook. Such fish hook may be individual or attached
to longline or mainline and such fish hook may have a single or
multiple hooks.
[0014] According to a third non-limiting aspect of the present
invention, an apparatus is provided comprising a surfboard and an
electropositive metal.
[0015] In fourth non-limiting aspect of the present invention, a
method is provided for repelling elasmobranchs comprising attaching
an electropositive metal to a human body or to clothing or
accessories associated with a human body. In an aspect of the
invention, an electropositive metal may be attached to a human
ankle or wrist. In a further aspect an electropositive metal may be
attached to a bracelet. In yet a further aspect an electropositive
metal may be attached to a belt, a weight belt for diving or
flippers. In yet a further aspect, an electropositive metal may be
housed within a surfboard or attached to a surfboard. In yet
another aspect, an electropositive metal may be trailed along with
a human in water.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The invention will now be described by way of example with
reference to the accompanying drawings wherein:
[0017] FIG. 1 illustrates a traditional circle hook (40) attached
to a line (30) and preferred zone (I) for locating an
electropositive metal in accordance with the present invention.
[0018] FIGS. 2A-C illustrate non-limiting positions within the zone
(I) for locating an electropositive metal in accordance with the
present invention. FIG. 2A illustrates an electropositive metal
attached to the line above the hook. FIG. 2B illustrates an
electropositive metal attached to the hook. FIG. 2C illustrates an
electropositive metal attached to the hook shank and clear of the
hook eye.
[0019] FIG. 3A-C illustrate non-limiting positions within the zone
(I) for locating an electropositive metal on a J-hook in accordance
with the present invention. FIG. 3A illustrates an electropositive
metal attached to the line above the hook. FIG. 3B illustrates an
electropositive metal attached to the hook. FIG. 3C illustrates an
electropositive metal attached to the hook shank and clear of the
hook eye.
[0020] FIG. 4A-B illustrate non-limiting positions within the zone
(I) for locating an electropositive metal on a treble hook in
accordance with the present invention. FIG. 4A illustrates an
electropositive metal attached to the line above the hook. FIG. 4B
illustrates an electropositive metal attached to the hook.
[0021] FIG. 5 illustrates a demersal longline with an
electropositive metal in accordance with the present invention.
[0022] FIGS. 6A-B illustrate non-limiting apparatuses and methods
of repelling elasmobranchs in accordance with the present
invention. FIG. 6A illustrates a buoy and electropositive metal and
a net with a plurality of electropositive metals in accordance with
the invention. FIG. 6B illustrates a barge and an electropositive
metal.
[0023] FIGS. 7A-B illustrate non-limiting surfboards with an
electropositive metal in accordance with the invention. FIG. 7A
illustrates a surfboard with an electropositive metal that is
capable of spinning in accordance with the invention. FIG. 7A
illustrates a surfboard with an electropositive metal embedded in
or attached to the surfboard in accordance with the invention
[0024] FIGS. 8A-C illustrate accessories for attaching an
electropositive metal to a human or other subject or object. FIG.
8A illustrates a belt or weight belt with an electropositive metal
in accordance with the invention. FIG. 8B illustrates a bracelet or
wristband with an electropositive metal in accordance with the
invention. FIG. 8C illustrates flippers for snorkeling or diving
with an electropositive metal in accordance with the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0025] "By-catch" is any kind of fish that is caught in a fishing
operation wherein the catching of the fish is not the object of the
fishing operation. For example, if the target fish of a longline
fishing operation is tuna, an elasmobranch caught on a hook of the
longline is by-catch.
[0026] "Elasmobranchs" in this specification means one or more
elasmobranchii in the super-orders Galeomorphii, Squalomorphii, and
Batoidea and orders Squaliformes (dogfish), Carcharhiniformes
(requiem sharks), Lamniformes (mackerel sharks), Rajiformes (true
rays), Pristiformes (sawfishes), Torpediniformes (electric rays)
and certain Orectolobiformes (carpet sharks). Elasmobranchs in this
specification includes nurse sharks, an Orectolobiform, but this
specification does not include the other carpet sharks, such as
wobbegongs.
[0027] An "Electropositive metal" is a metal which readily donates
electrons to form positive ions. Electropositive metals are strong
reducing agents and all react with water to some degree, typically
liberating hydrogen gas or forming a hydroxide. The most
electropositive metals tends to be found on the left-hand side of
the Periodic Table of the elements, particularly in Groups I, II,
III, and the Lanthanides. In general, electropositivity decreases
and electronegativity increases as one moves to the right hand side
of the Periodic Table of the elements. The most electropositive
metal known is Francium, which is radioactive. The most stable
electropositive metal is Cesium which is highly reactive in water
and air. Electropositive metals typically do not exhibit any
permanent magnetism (ferromagnetism) at room temperature.
[0028] "Revised Pauling Electronegativity" is is a chemical
property which describes the power of an atom to attract electrons
towards itself. First proposed by Linus Pauling in 1932 as a
development of valence bond theory it has been shown to correlate
with a number of other chemical properties. Electronegativity
cannot be directly measured and must be calculated from other
atomic or molecular properties The Pauling electronegativity for an
element is calculated using the dissociation energies of at least
two types of covalent bonds formed by that element. Linus Pauling's
original values were updated in 1961 to take account of the greater
availability of thermodynamic data, and it is these "Revised
Pauling" values of the electronegativity which are most usually
used.
[0029] "Standard Electrode Potential" is the measure of the
individual potential of any electrode at standard ambient
conditions, which is at a temperature of 298K, solutes at a
concentration of 1 M, and gases at a pressure of 1 bar. The basis
for an electrochemical cell such as the galvanic cell is always a
reduction-oxidiation reaction which can be broken down into two
half-reactions: oxidation at anode (loss of electron) and reduction
at cathode (gain of electron). Electricity is generated due to
electric potential difference between two electrodes. This
potential difference is created as a result of the difference
between individual potentials of the two metal electrodes with
respect to the electrolyte (In practice, seawater serves as the
conductive electrolyte). In an electrochemical cell, an
electropositive metal acts as the cathode, and the standard
electrode potential represents the voltage of the reduction
half-cell reaction.
[0030] A "Lanthanide metal" belongs to the series comprising the 15
elements with atomic numbers 57 through 71, from Lanthanum to
Lutetium. All lanthanides are f-block elements, corresponding to
the filling of the 4f electron shell, except for lutetium which is
a d-block Lanthanide. The Lanthanide series is named after
Lanthanum. The Lanthanide series is also commonly referred to as
the "rare earths" or "rare earth elements".
[0031] "Mischmetal" is an alloy of Lanthanide elements in various
naturally-occurring proportions. The term "Mischmetal" is derived
from the German "Mischmetal" meaning mixed metals. Mischmetals are
also called Cerium mischmetal, rare earth mischmetal or misch
metal. A typical composition includes approximately 50% Cerium and
45% Lanthanum, with small amounts of Neodymium and Praseodymium.
Other Mischmetal alloy mixtures include Lanthanum-rich Mischmetal,
Ferrocerium, and Neodymium-Praseodymium Mischmetal.
[0032] An "Alkaline Earth" metal belongs to the series of elements
comprising Group 2 of the Periodic Table of elements: Beryllium,
Magnesium, Calcium, Strontium, Barium, and Radium. The alkaline
earth metals are silvery colored, soft, low-density metals, which
react readily with halogens to form ionic salts, and with water to
form strongly alkaline hydroxides.
[0033] An "Alkali Earth" metal belongs to the series of elements
comprising Group I of the Periodic Table of elements: Lithium,
Sodium, Potassium, Rubidium, Cesium, and Francium. The alkali
metals are all highly reactive and are rarely found in elemental
form in nature. As a result, in the laboratory they are stored
under mineral oil. They also tarnish easily and have low melting
points and densities.
[0034] A "Group 3 metal" belongs to the third vertical column of
the Periodic Table of elements. While Lanthanides are usually
considered part of Group 3, the metallic elements Yttrium and
Scandium all always considered Group 3 metals. The physical
properties of Yttrium and Scandium resemble Lanthanides and these
two metals are commonly considered part of the "rare earths".
[0035] "Longline" refers to a fishing line that may extend up to
many miles wherein a mainline extends the full length of the
longline and individual shorter gangion lines attached to the
mainline are spaced at set intervals (perhaps several feet or
meters or perhaps 1000 feet or greater apart). Hooks are attached
to the individual gangion lines. Hooks may be baited and used to
catch target fish. The addition of an electropositive metal repels
elasmobranchs from the baited hooks as well as from the region of
the longline generally.
[0036] "Target fish" is any kind of fish, the catching of which is
the object of a fishing operation. For example, the target fish of
a longline fishing operation may be tuna. A fish that is caught on
the longline that is not tuna would not be a target fish.
[0037] "Tonic immobility" is the state of paralysis that typically
occurs when an elasmobranch is subject to inversion of its body
along the longitudinal axis of the body, i.e., is belly up. An
elasmobranch can remain in this state for up to 15 minutes. While
in tonic immobility, the shark is comatase and unresponsive to many
external stimuli. Biologists often perform surgery on sharks using
tonic immobility, precluding anesthesia. An effective shark
repellent terminates tonic immobility, often violently, thus, tonic
immobility is useful as a bioassay for testing the effectiveness of
electropositive metals.
I. Electropositive Metals as Repellents of Elasmobranchs
[0038] The applicant first observed the unusual repellent effects
of electropositive Lanthanide metals on sharks when
tonically-immobilized juvenile lemon sharks (N. brevirostris)
exhibited violent rousing behavior in the presence of a 153 gram
99.95% Samarium metal ingot. As the Samarium metal was moved
towards the immobilized shark's head, the shark terminated tonic
immobility, in the direction away from the approaching metal. For
experimental controls, pure Chromium, an antiferromagnetic metal,
and pyrolytic graphite, a highly diamagnetic substance, failed to
produce any behavioral responses in juvenile lemon sharks.
[0039] A polystyrene white plastic blinder was used to remove any
visual and motion cues from an approaching electropositive metal.
This blinder was placed close to the shark's eye, sufficiently
shielding its nares, eyes, gills, and head up to its pectoral fin.
Again, Samarium metal terminated tonic immobility in all test
subjects at a range of 2 to 50 cm from the blinder. Chromium metal
and pyrolytic graphite did not produce any notable behavioral
shifts. In order to confirm that pressure waves were not affecting
the test subjects, the tester's hand was moved underwater towards
the shark's head both with and without blinders at varying speeds.
This motion also did not disrupt the immobilized state. The same
series of experiments were repeated with juvenile nurse sharks (G.
cirratum) and yielded the same behavioral results.
[0040] The same experimental protocol was repeated with a 73 gram
ingot of 99.5% Gadolinium metal, an electropositive Lanthanide
metal, and yielded the same behavioral results in both juvenile
lemon sharks and nurse sharks. It is noted that the rousing
behavior was most violent when Samarium metal was used.
Additionally, the Gadolinium metal corroded quickly after seawater
exposure, and therefore would be appropriate for a one-time use
application.
[0041] In order to eliminate the possibility of galvanic cell
effects, juvenile sharks were removed from their pens and brought
at least 15 meters away from any submerged metal objects. All
testers and witnesses removed watches, rings, and jewelry so that
only the lanthanide metal was exposed to seawater. The same
experimental method was repeated in lemon sharks and we report that
tonic immobility was terminated with electropositive Samarium metal
in all tests.
[0042] The application has discovered that waving Samarium or
Gadolinium in air above immobilized or resting sharks does not
effect behavior, even when the metal is very close to the water's
surface. The electropositive metal must be in contact with seawater
in order to produce the repellent effect. This is notably different
from the effects of a rare-earth magnet, which will often terminate
tonic immobility at close range in air.
[0043] The effects of an electropositive Lanthanide metal on
free-swimming sharks were also evaluated. Two juvenile nurse sharks
(less than 150 cm total length) were allowed to rest in an
open-water captive pen. The tester approached the nurse sharks and
moved his hand near the pen wall. His hand contained no metal. Both
nurse sharks remained at rest. Next, the tester presented the 153
gram ingot of electropositive Samarium metal underwater to the pen
wall and we note that both nurse sharks awakened and rapidly swam
away from the tester's locale. Next, a highly-stimulated
competitively-feeding population of six blacknose sharks (C.
acronotus) (total length up to 120 cm) and six Caribbean reef
sharks (C. perezii) (total length up to 210 cm) was established
using chum and fish meat. A diver entered the water near the
population of sharks with the 153 gram of Samarium metal secured to
one end of a 1.5 meter-long polyvinyl chloride pole. As
free-swimming sharks swam close to the diver, the control end of
the pole (without metal) was presented in a left-right waving
motion. Approaching sharks would swim past, bump, or briefly bite
the pole. The diver then turned the Samarium metal-end of the pole
towards the approaching sharks. All blacknose sharks exhibited a
"twitching" or "jerking" behavior as they came near the metal ingot
and quickly swam away. Caribbean reef sharks generally avoided the
metal, but did not exhibit the twitching behavior.
[0044] Following the aforementioned initial experiments, many
electropositive metals were procured and presented to
tonic-immobilized juvenile sharks. The violence of the shark's
response to each metal was scored on a scale of 0 to 4, with 0
equating to no response and 4 equating to a violent rousing
reaction. All testing was performed in the Bahamas using open-water
captive pens. Arc-melted 100 gram Lanthanide metal ingots, Calcium,
and Strontium were obtained from Metallium Inc., USA. Lanthanum,
Cerium, Neodymium, Yttrium, Praseodymium and Mischmetal samples
were obtained from HEFA Rare Earth Metals, Canada. Magnesium,
Beryllium, transition metals and nonmetals were procured as surplus
items online from EBay.
[0045] In juvenile N. brevirostris and G. cirratum, the applicant
has found that the following Lanthanide metals all terminated the
tonic state at distances less than 0.1 meters: 100 grams of 99%
purity Lanthanum metal, 90 grams of 99% purity Cerium metal, 100
grams of 99% purity Praseodymium metal, 100 grams of 99% purity
Neodymium metal, 73 grams of 99.95% purity Samarium met al, 145 g
of arc-melted 99% purity Terbium metal, 89 g of arc-melted 99%
purity Erbium metal, 100 grams of arc-melted 99% purity Holmium
metal, 100 grams of arc-melted 99% Gadolinium metal, 100 grams of
arc-melted 99% Dysprosium metal, and 100 grams of arc-melted 99%
purity Ytterbium metal.
[0046] In the same experiment, 75 grams of 99% purity Yttrium
metal, a Group 3 metal, also terminated tonic immobility in
juvenile N. brevirostris.
[0047] In the same experiment, a 30 gram 99% purity ingot of
Strontium and separately, a 40 gram 99% purity ingot of Calcium
terminated tonic immobility in juvenile G. cirratum. These metals
were highly reactive in seawater and dissolved before a second
series of tests could be performed.
[0048] In the same experiment, the following Mischmetals terminated
tonic immobility in N. brevirostris: An 80 gram slice of Cerium
Mischmetal, and a 100 gram slice of Neodymium-Praseodymium
Mischmetal.
[0049] In the same experimental, the following Alkaline Earth
metals terminated tonic immobility in N. brevirostris: A 70 gram
block of 99% Magnesium, and a 10 gram pellet of 99% purity Barium.
The Barium pellet reacted violently with seawater and a subsequent
test could not be performed.
[0050] Transition metals and nonmetals, which are much less
electropositive than the Lanthanides, Alkali, Alkaline Earth, and
Group 3 metals, were also screened using the tonic immobility
bioassay. The following transition metals and metalloids failed to
illicit a rousing response in immobilized juvenile N. brevirostris:
A 20 gram disc of 99.95% purity Tellurium, a 20 gram cylinder of
99.5% purity Tungsten, a 20 gram cylinder of 99.5% purity Cobalt, a
20 gram cylinder of 99.5% purity Iron, a 20 gram cylinder of 99.5%
purity Niobium, a 20 gram cylinder of 99.5% purity Zirconium, a 20
gram square of 99.95% Rhenium, a 100 gram pillow of Aluminum, and a
15 gram square of pyrolytic graphite (Carbon).
[0051] Based on the aforementioned experimental results, a close
correlation was found between the revised Pauling electronegativity
values for the electropositive metals, and behavioral response. As
the revised Pauling electronegativity decreased, the violence of
the shark's response seemed to increase. A significant repellency
threshold was found at a revised Pauling electronegativity of 1.32
or less--Metals with electronegativities greater than 1.32 did not
produce the response. Highly reactive metals, such as Strontium and
Calcium (electronegativities of 0.89 and 1.00 respectively)
produced a violent rousing reaction as expected.
[0052] An electropositive metal for repelling elasmobranchs may
comprise the 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,
a tapered cone, or any other shape.
[0053] The mode of action of electropositive metals on
elasmobranchs is not fully understood. While not wishing to be
bound by any particular theory, one plausible theoretical
explanation for this surprising finding of repellent activity of
electropositive metals is the possibility that relatively high
voltages, ranging from 0.8 VDC to 2.7 VDC with currents up to 0.1
milliamperes, are created between the metal and the shark's skin.
This electromotive force may over-stimulate the ampullae of
Lorenzini (known to be used by elasmobranchs for navigation and
orientation), which saturate below 100 nanovolts, causing a highly
unnatural stimulus to the shark.
[0054] Electropositive metals exhibit no measurable permanent
magnetism (ferromagnetism). The applicant hypothesized that a
magnetic or electrical field was being induced by the metal's
movement through seawater. The applicant attempted to measure
minute magnetic fields being produced by the movement of Samarium
metal through seawater in a closed system. A submersible calibrated
milliGauss meter probe was secured in a plastic tank containing
seawater with the same salinity, pH, and temperature of the water
used in previous shark testing. After zeroing out the Earth's
magnetic field, the applicant did not detect any magnetic fields
being produced by the movement of Samarium metal through the tank,
within tenths of a milliGauss
[0055] Electromotive forces generated by electropositive metals are
effective repellents for elasmobranchs, excluding certain carpet
sharks in the family Orectolobidae. It is believed that
electropositive metals are not effective repellents against carpet
sharks because carpet sharks, particularly spotted wobbegongs
(Orectolobus maculatus), are ambush predators and rely more on
visual, olfaction, and lateral line clues than this electromagnetic
sense. This species of shark is found chiefly in Australia and
Indonesia, and does not represent significant by-catch species or
species that are known to be aggressive against humans.
Electropositive metals, however, are effective against nurse
sharks, another Orectolobiform.
[0056] Electropositive metals have been demonstrated to act as
acceptable repellents of elasmobranchs. The repellent activity of
electropositive has been shown to be better than existing
shark-repellent technology with the exception of certain chemical
repellents and magnetic repellents being developed by SHARK DEFENSE
LLC that have a greater range of action.
[0057] A. Electromotive Forces
[0058] The repellency of an electropositive metal may be measured
in a variety of ways. The applicant has found that the standard
electrode potential of the cathode half-cell reaction of an
electropositive metal in aqueous medium can be measured in a closed
system using an electropositive metal at the anode (the site of
oxidation), a piece of shark skin at the cathode (the site of
reduction), and seawater as an electrolyte. Electromotive forces
were measured using a calibrated direct current voltmeter.
Electromotive forces greater than 0.8 volts were recorded for all
electropositive metals, with Lithium metal, an Alkali earth metal,
producing the highest measurable voltage at 2.71 volts. This
demonstrated that cations and anions were exchanged through the
electrolyte. These measured electromotive forces closely correlated
to published standard electrode potentials for electropositive
metals. A closed system using an electropositive metal at the
external cathode (-) and a piece of shark skin at the external
anode (+) with seawater electrolyte represents a simple and
effective means of measuring electromotive forces and predicting
repellency.
[0059] The strength of an electropositive metal's electromotive
force field is inversely related to the distance an object is from
the metal. As such, metals with a low standard electrode potential
may repel elasmobranchs if the elasmobranch moves close enough to
sense the electromotive force field of the metal. A highly
electropositive metal having sufficient strength to repel an
elasmobranch at sufficient distance such that the elasmobranch is
deterred from striking a baited hook or coming near a person or
other subject is preferred. It is more preferred that an
electropositive metal have a standard electrode potential of at
least 2.00 volts in seawater to provide sufficient electromotive
force to repel an elasmobranch away from a baited hook or a person
before the elasmobranch may bight the hook or harm the person.
Because an elasmobranch may act to strike a hook or person at a
distance from the target, the higher the standard electrode
potential or the lower the revised Pauling electronegativity of the
metal, the more effective it will be.
II. Methods and Devices for Electropositive Metals
[0060] A. Electropositive Metals
[0061] Exemplary and non-limiting electropositive metals in
accordance with the invention may be constructed of any metal that
is capable of generating an electromotive force in seawater
relative to the shark's skin.
[0062] Electromotive forces may be generated in any manner known to
the skilled artisan who is practicing aspects of the invention or
electrochemistry.
[0063] There are many varieties of electropositive metals including
the Lanthanide metals, the Alkaline Earth metals, the Alkali
metals, Mischmetals, and the Group 3 metals on the periodic table
of elements. Any electropositive metal having sufficient standard
electrode potential or a low revised Pauling electronegativity may
be used as a repellent of elasmobranchs.
[0064] Exemplary electropositive metals include Lanthanum, Cerium,
Neodymium, Praseodymium, Samarium, Europium, Gadolinium, Terbium,
Dysprosium, Holmium, Erbium, Thulium, Ytterbium, Lutetium, Yttrium,
Scandium, Lithium, Magnesium, Calcium, Strontium, Barium, Cerium
Mischmetal, Neodymium-Praseodymium Mischmetal, and Lanthanum-rich
Mischmetal. Electropositive metals may be flexible or
inflexible.
[0065] A preferred electropositive metal contemplated within an
aspect of the invention is Neodymium-Praseodymium Mischmetal.
Neodymium-Praseodymium Mischmetal is a more preferred material than
pure forms of Lanthanide or Alkaline earth metals due to cost and
low corrosion reactivity in seawater. Pure Lanthanide metals,
particularly the "late Lanthanides" comprising elements 63 through
71, are prohibitively expensive in pure form. Pure Alkali metals
are extremely reactive in seawater and present fire hazards in
storage. Certain Alkaline earth metals are also highly reactive in
seawater, such as Barium and are too short-lived for commercial
fishing applications. Highly electropositive metallic elements such
as Promethium, Radium, and Francium are highly radioactive and are
not feasible for any elasmobranch repelling application.
[0066] In selecting an electropositive metal, a revised Pauling
electronegativity of less than 1.32 is preferred. A revised Pauling
electronegativity of about 1.14 or less is more preferred since the
impact of the electromotive force field will be felt at a slightly
greater distance from the metal.
[0067] Early Lanthanide metals, particularly elements 57 through
62, commonly called the "early Lanthanides", possess revised
Pauling Electronegativities less than 1.2, which is preferred.
Similarly, Mischmetals containing combinations of Lanthanum,
Cerium, Neodymium, and Praseodymium exhibit calculated revised
Pauling electronegativities of less than 1.2, which is
preferred.
[0068] In order to maximize electromotive forces, the surface area
of an electropositive metal may be maximized. For example, a 6''
diameter by 2'' thick cylindrical Cerium Mischmetal block (revised
Pauling electronegativity of 1. 15) may be effective in repelling
elasmobranchs at a range of 8 inches.
[0069] A plurality of electropositive metals may be employed to
repel elasmobranchs. For example, 1'' cube metals may be arranged
in a 12'' long bar and used to repel elasmobranchs. The cube metals
may be of any electropositive metal material capable of producing
sufficient electromotive force at any distance of interest from the
metal to repel elasmobranchs. Alternatively, a plurality of 1''
cube electropositive metals may be arranged linearly with a
distance between each piece of metal.
[0070] B. Electropositive Metals in Combination with Hooks
[0071] A non-limiting aspect of the present invention is the use of
electropositive metals to repel elasmobranchs from baited hooks.
Exemplary and non-limiting combinations of an electropositive metal
and a hook are illustrated in FIGS. 14. For example, in FIG. 1, an
exemplary and non-limiting circle hook (140) is illustrated
attached to a line (150) along with exemplary and non-limiting zone
(I) in the circle hook and line where an electropositive metals may
be placed or affixed. The preferred region (zone I) for metal
placement is any region wherein the affixed or placed magnet does
not obstruct the hook gap distance (zone II). Not more than 20% of
the hook gap distance (zone II) is preferably obstructed by the
metal such that the hook is not prevented from setting in the
corner of the mouth of a target fish. Nevertheless, any arrangement
wherein the hook is not prevented from catching target fish is
acceptable. Tapered conical designs (not illustrated) are
contemplated such that the diameter of the electropositive metal at
the hook end is smaller than the diameter of the electropositive
metal at the line end of zone I.
[0072] Exemplary and non-limiting combinations of an
electropositive metal on a hook and line are illustrated in FIG. 2.
An electropositive metal (210) may be placed in proximity to a
circle or offset circle hook (240) such that it rests on the hook
eye (241) providing an exemplary embodiment such as the hook-metal
combination embodied at 260. An electropositive metal (210) may be
placed in proximity to a circle or off-set circle hook (240) such
that it rests on the shank (242) of the hook providing an exemplary
embodiment such as the hook-metal combination embodied at 270. A
metal (210) may be placed on a circle or offset circle hook (240)
such that it is secured to the outside of the shank (242) and the
hook eye (241) providing an exemplary embodiment such as the
hook-metal combination embodied at 280. Vinyl electric tape (not
illustrated) may be used to secure the metal. Black vinyl tape is
preferred to reduce reflections of light.
[0073] Electropositive metals may be provided in any shape. It is
preferred that a metal's shape not significantly obstruct the hook
gap distance (zone II). The metal may comprise a hole through which
a lead, or gangion, or mainline (250) or other filamentous object
may pass. Exemplary non-limiting shapes may include a cube or block
of any size or other object having at least one plane comprising
four right angles and a hole passing through the object such that
fishing line or other filament may be passed through to affix the
magnet in place on fishing tackle or other object. Alternative,
non-limiting shapes may also include cylindrical or other circular,
oval or oblong three-dimensional shapes having a hole passing
through some portion of the shape (210). Alternative, non-limiting
shapes may also include a hollow pyramid or a hollow trapezoid.
[0074] Alternative, non-limiting shapes may also include a solid
cube or similar shape, a solid rectangle or similar shape, a solid
bar or similar shape, a solid pyramid or similar shape, a solid
trapezoid or similar shape or any other shape. Metals may be shaped
as a ring, a trapezoid, a series of trapezoids, a series of
trapezoids arranged in a larger ring pattern, a cone, a tapered
cone, a narrow or wide cylinder or in the shape of a Billy club.
Preferably, the shape when combined with a hook provides a hook in
proximity to an electropositive metal comprising sufficient
electromotive force field strength to repel elasmobranchs.
[0075] Exemplary and non-limiting combinations of electropositive
metal and hook are also illustrated in FIG. 3. An electropositive
metal (310) may be placed in proximity to a j-hook (340) such that
it rests on the hook eye (341) providing an exemplary embodiment
such as the hook-metal combination embodied at 360. An
electropositive metal (310) may be placed in proximity to a j-hook
(340) such that it rests on the shank (342) of the hook providing
an exemplary embodiment such as the hook-metal combination embodied
at 370. An electropositive metal (310) may be placed on a j-hook
(340) such that it is secured to the outside of the shank (342) and
the hook eye (341) providing an exemplary embodiment such as the
hook-metal combination embodied at 380. As described above in the
illustration of FIG. 2, electropositive metal may be provided in
any shape.
[0076] Exemplary and non-limiting combinations of an
electropositive metal and hook are also illustrated in FIG. 4. An
electropositive metal (410) may be placed in proximity to a treble
hook (440) such that it rests on the hook eye (441) providing an
exemplary embodiment such as the hook-metal combination embodied at
460. An electropositive metal (410) may be placed in proximity to a
treble hook (440) such that it contacts the shank (442) of the hook
providing an exemplary embodiment such as the hook-metal
combination embodied at 470.
[0077] A hook in accordance with the invention may be any hook that
is capable of catching target fish. The hook may comprise stainless
steel, steel, galvanized metals, ferromagnetic metals or any other
material, metallic or plastic or any other composite.
[0078] C. Electropositive Metals on Longlines
[0079] An exemplary and non-limiting method of repelling
elasmobranchs involving repelling elasmobranchs from longlines in
accordance with the invention is illustrated in FIG. 5. A longline
(500) may be deployed from a boat (561) to fish for a target fish
of interest. The main line (550) of the longline may be attached to
a buoy (520) and at a set distance from the buoy may be attached to
an anchor (562). A set of gangions (530) with hooks (540) may be
attached to the mainline beginning at the anchor (562) and may be
spaced sufficiently to limit interaction between individual gangion
lines (530). Each hook may have an electropositive metal mounted
resting on the hook eye (541). Alternatively, the electropositive
metal may be mounted on a hook shank (542) or may be secured to the
outside of the hook (540). The hooks may be baited. The longline
may be a demersal longline such that the main line is proximal to
the ocean or otherwise water's floor. The longline may be a pelagic
long line, such that the main line is nearer to the surface of the
water, suspending in the water column, typically at 100-500 feet
below the surface. In the aspect of the invention where the
longline is a pelagic longline, anchors (562) may have less weight
or may be absent from the longline apparatus. The longline may also
be a semipelagic longline wherein the mainline is further down the
water column from the surface as compared to a pelagic line but is
not proximal to the water's floor or is not proximal to the water's
floor on at least one end of the longline. Use of electropositive
metals with longlines reduces by-catch of elasmobranchs.
[0080] Longlines comprising electropositive metals may be handled
in the commercial environment in a manner similar to those
practices known in the art of longline commercial fishing. Because
hooks must be carefully managed to control tangling and hooking of
objects on a longlining boat, including other portions of the
tackle of the longline, commercial fishing operations and those of
skill in the art will recognize how to handle longlines with hooks.
Electropositive metals on longlines likewise may be handled in the
same manners as one would consider appropriate in the art to avoid
entanglements.
[0081] As described above, electropositive metals of any size may
be used in combination with a longline hook so long as the target
fish may be caught on the hook. An exemplary electropositive metal
on a longline hook may be 2''.times.0.25''.times.2''. Smaller
electropositive metals are also acceptable. Electropositive metals
of less than 0.5'' cubed may be appropriate for smaller hook
settings.
[0082] D. Electropositive Metal Repellents on Buoys, Nets and
Barges
[0083] An exemplary and non-limiting method of repelling
elasmobranchs with an electropositive metal or a plurality of
electropositive metals placed on a buoy or barge or net is
illustrated in FIG. 6. Buoys with electropositive metals as their
weighted bases are shown as element 660 and 661 in FIG. 6A. The
floating portion of the buoy (620) allows the buoy to float while
the electropositive metal portion of the buoy (610) remains in the
water because of its weight. A series of buoys comprising
electropositive metals may be placed in a region to repel
elasmobranchs or may be placed around a swimming area or rescue
area to repel elasmobranchs. A series of buoys with electropositive
metals may be accompanied by a series of electropositive metals
submerged (611) in an area of interest, such as a swimming area. As
illustrated in FIG. 6B, very large electropositive metals may be
placed on a large floating barge (670) comprising an
electropositive metal (610).
[0084] An exemplary and non-limiting method of repelling
elasmobranchs with a plurality of electropositive metals is
illustrated in FIG. 6A as element 600, an elasmobranch repelling
net apparatus. Buoys (660 and 661) may be employed to float a net
(650) comprising a series of electropositive metals (640) held
within the net and electropositive metal rings (630) holding the
ropes of the net together. The net may be strung to the bottom of
the water column using weighted electropositive metals (611). The
net may be anchored to a specific location to provide a physical
barrier. The net may provide a curtain of electromotive field
forces to repel elasmobranchs from an area or to keep elasmobranchs
from entering an area of interest, such as a swimming or working
area. A net (650) comprising electropositive metals such as those
illustrated as elements 610, 611, 630 and 640 may also be used to
trawl for fish, shrimp or other aquatic species. In another
non-limiting aspect of the invention, electropositive metals may be
placed in aquaculture cages to repel sharks from predation or
scavenging of cultured stock. Electropositive metals are useful to
prevent damage by elasmobranchs to aquaculture cages, nets or other
equipment.
[0085] E. Surfboard Fitted with Electropositive Metal
[0086] A non-limiting repelling device in accordance with the
invention may comprise a surfboard comprising an electropositive
metal device. FIG. 7B illustrates exemplary surfboards in
accordance with an aspect of the invention. A surfboard (720) may
comprise an electropositive metal device such as Mischmetal (710)
imbedded, affixed, attached or otherwise associated in any manner
contemplated by one of skill in the art with the surfboard An
electropositive metal may be pressed into a space drilled into the
surfboard (730). It may also be affixed with glue, waterproof tape,
Velcro or any other mechanism known in the art now and
hereafter.
[0087] In an alternative non-limiting example in Figure A, a
surfboard (750) may comprise an electropositive metal or plurality
of electropositive metals in association with one another wherein
the electropositive metal or metals are capable of spinning when
placed in water (740). Such a spinning electropositive metal (740)
may comprise individual metal pieces attached to a hub (770) that
is attached to an axle (760) to allow free spinning of the
electropositive metal or metals attached to the surfboard (720)
when water current is present.
[0088] An electropositive metal may be enclosed in the body of a
surfboard or other watercraft or may be trailed behind a surfboard,
other watercraft or swimmer.
[0089] F. Electropositive Metal Repellents on Swimming and Diving
Clothing and Accessories
[0090] One exemplary non-limiting aspect of the present invention
comprises an electropositive metal material for producing an
electromotive force field near a swimmer or diver or other person
or object in an elasmobranch environment.
[0091] Electropositive metals, such as for example, Mischmetal, or
other electropositive metals may be worn as a bracelet or a band or
otherwise placed in proximity of a person or object. An increase in
the number of electropositive metals and an increase in the
standard electrode potential of the metals that may be worn
increases the electromotive force field around the wearer and
increases the repelling activity of the bracelet, band or other
metal article.
[0092] In a non-limiting example, an omnidirectional electromotive
force field may be affixed or arranged near a subject or object
exposed to an elasmobranch environment. The electromotive force
field may be generated from, for example, an electropositive metal.
An electropositive metal may be affixed, for example, to any
portion of a swimmer's or diver's body such as the head, the leg,
the arm, the torso, the ankle, the wrist, or any other portions of
the body.
[0093] FIG. 8 illustrates a non-limiting example of electropositive
metals (810) attached to a belt (801) (FIG. 8A) or bracelet (802)
(FIG. 8B) or flippers (803) (FIG. 8C).
[0094] Electropositive metals may likewise be attached to clothing
or water accessories such as swim trunks, wet suits, headbands,
flippers, goggles or other piece of clothing or accessory.
Electropositive metals may be sewn into such clothing or may be
affixed with tape, glue, Velcro or any other mechanism for affixing
to clothing or accessories for swimming, diving or otherwise
working or playing in water.
[0095] Many human-shark interactions in shallow water, especially
around the State of Florida in the United States, are hypothesized
to be "mistaken identity" by the shark in water with poor
visibility. The blacktip shark (C. limbatus) and nurse shark (G.
cirratum) are often implicated in these encounters. The sharks do
not have an olfactory clue in most of these "mistaken identity"
cases. A series of electropositive metals, such as Mischmetal or
other electropositive metal, may be used as means to repel the
shark as it approaches within a few inches of the metal. With an
electropositive metal, such as Cerium, or an increased number of
electropositive metals, to increase electromotive force field
strength, repellent activity increases and the chance that a shark
will be repelled prior to an investigatory bump or bite is greatly
increased.
[0096] The invention is further described with the following
non-limiting examples, which are provided to further illuminate
aspects of the invention.
III. EXAMPLES
Example 1
Tonic Immobility Responses to Electropositive Metals
[0097] In order to screen the repellency potential of various
metals, 193 individual trials were conducted on juvenile sharks at
South Bimini, Bahamas in open ocean pens. All sharks were placed
into tonic immobility, and the behavioral response of the shark
towards a test metal was scored using a scale of 0 to 4. A score of
zero represented no response, with the shark remaining immobilized.
A score of one represented a slight fin flinch or eye blink. A
score of two represented a slight bend (less than 15 degrees) away
from the metal, without rousing. A score of three represented a
strong bend away from the metal (more than 15 degrees), without
rousing. A score of four represents the termination of tonic
immobility, with a rousing response, indicating adequate
repellency. No more than three consecutive trials were performed on
any one given shark. A minimum of 4 hours of rest was allotted
before a shark was retested. Classifying the behavioral scores with
a specific group on the Periodic Table of the element demonstrates
that the electropositive metals found in Group 2 and Group 3 of the
periodic table of elements produced a stronger repellent response
than transition metals (Groups3 through 12), a poor metal (Group
13), a metalloid (Group 16), and a nonmetal (Group 14). See Table
1. TABLE-US-00001 TABLE 1 Group Tests (Periodic table) Performed
Average Score Group 1 1 4 Group 2 13 3.23 Group 2 Alloy 34 2.79
Group 3 84 2.28 Group 8 6 1.17 Group 13 4 0.75 Group 5 5 0.20 Group
14 21 0.10 Group 9 5 0 Group 7 6 0 Group 6 4 0 Group 4 5 0 Group 16
6 0
[0098] The aforementioned tests can also be analyzed in terms of
the type of metal tested on the immobilized sharks. As expected,
Alkali metals, Alkaline earths, Mischmetals, early Lanthanides, and
late Lanthanides produced the highest repellency behavioral scores.
These types of metals are electropositive and have revised Pauling
electronegativities less then 1.32. See Table 2. TABLE-US-00002
TABLE 2 Tests Type of metal Performed Average Score Alkali metal 1
4 Alkaline earth 13 3.23 Mischmetal 34 2.79 Early Lanthanide 49
2.66 Late Lanthanide 29 1.83 Rare Earth 6 1.333 Poor metal 4 0.75
Transition metal 31 0.26 Nonmetal 21 0.10 Metalloid 6 0
Example 2
Published Standard Electrode Potentials of Electropositive
Metals
[0099] The published standard electrode potentials (SEP) for the
cathode half-cell reaction of electropositive metals is a practical
means of determining the repellency of the metal without performing
a bioassay. As the cathode half-cell reaction voltage increases,
the repellent effect is also expected to increase. The published
voltage represents the electromotive force between the
electropositive metal and the reference electrode. Published
standard electrode potentials typically use a standard hydrogen
electrode as the reference electrode. In practice, shark skin is
the reference electrode and produces measurable voltages at about
88% of the published standard electrode potentials. The safe
handling of highly electropositive metals must be considered, as
well as the longevity of the metal in seawater. See Table 3.
TABLE-US-00003 TABLE 3 Cathode SEP Terminates Tonic metal (Volts)
Immobility? Safety Comments Lithium 3.05 YES Short-lived in water
Rubidium 2.98 PROBABLE Explosive in water Potassium 2.93 PROBABLE
Fire hazard in water Cesium 2.92 PROBABLE Explosive in water Barium
2.91 PROBABLE Short-lived in water Strontium 2.89 YES Short-lived
in water Calcium 2.76 YES Short-lived in water Sodium 2.71 PROBABLE
Fire hazard in water Lanthanum 2.52 YES Safe for repellent use
Cerium 2.48 YES Safe for repellent use Praseodymium 2.47 YES Safe
for repellent use Neodymium 2.44 YES Safe for repellent use
Samarium 2.41 YES Safe for repellent use Europium 2.41 PROBABLE
Corrodes quickly in air Gadolinium 2.40 YES Safe for repellent use
Terbium 2.39 YES Safe for repellent use Magnesium 2.38 YES Safe for
repellent use Yttrium 2.37 YES Safe for repellent use Dysprosium
2.35 YES Safe for repellent use Holmium 2.32 YES Safe for repellent
use Erbium 2.31 YES Safe for repellent use Thulium 2.31 PROBABLE
Safe for repellent use Lutetium 2.30 PROBABLE Safe for repellent
use Ytterbium 2.22 YES Safe for repellent use Beryllium 1.847 NOT
PROBABLE Weakly repellent, toxic oxides Aluminum 1.662 NO Not a
repellent Zirconium 1.45 NO Not a repellent Niobium 1.099 NO Not a
repellent Chromium 0.744 NO Not a repellent Rhenium 0.3 NO Not a
repellent Tungsten 0.1 NO Not a repellent
[0100] Beryllium and Magnesium metals are Alkaline earths in Group
2 of the periodic table of elements. These metals exhibit larger
revised Pauling electro-negativities (1.56 and 1.31 respectively)
than the Lanthanide metals. Magnesium, however, has a higher
standard electrode potential (see Table 3) than beryllium and
therefore is expected to be a better shark repellent than
beryllium. Tonic immobility testing has confirmed that magnesium
indeed produces aversive behavior in immobilized juvenile sharks.
It is anticipated the beryllium would be weakly repellent based on
the published standard electrode potentials. Additionally, the
highly toxic nature of beryllium compounds preclude its use as a
safe shark repellent.
Example 3
Target Fish not Repelled by Electropositive Metals
[0101] Preliminary research conducted on the effects of
electropositive metals on adult cobia, Rachycentron canadum,
suggests that electromotive forces produced by electropositive
metals had little effect on captive cobia. Digital video of cobia
striking at electropositive metals was recorded. Cobia were
observed directly biting electropositive metals as well as
transition metals. It is hypothesized that the shiny nature of the
metals acted as a visual attractant to the fish. Since bony fish
lack the ampullae of Lorenzini organ found in sharks, the fish were
unable to detect the electromotive forces produced by the
electropositive metals.
* * * * *