Note: Descriptions are shown in the official language in which they were submitted.
METHO~ AND APPARATUS FOR ATTRACTING
AQUATIC ANIMALS
The present invention relates to aquatic
animal-attracting apparatus and methods.
Fish-attracting devices are shown in the
following U.S. patents:
Hardin No. 3,854,234, issued Demcember 17, 1974
Gfroerer No. 2,765,575, issued October 9, 1956
Moffett No. 2,729,912, issued January 10, 1956
~uir et al. No. 2,434/220 issued January 6, 1948
The problem with such devices is that fish oil and
customary foods such as pieces of fish are used as
attractants and the fish-attracting capabilities of
customary foods are quickly dissipated. Also, the
oil and foods decompose if stored over an extended
period of time.
Apparatus for the slow release of pesticides
is shown in Callander U.S. patent No. 3,204,871,
issued September 7, 1965, and in Turner et al. U.S.
patent No. 2,738,224l issued March 13, 1956.
However, the apparatus of each of these patents is
u5ed for the release of vapor into the atmosphere.
Watkins U.S. patent No. 3,661,506, issued
May 9, 1972, discloses the use of a protective
membrane covering the hull of a ship to release
marine growth retardants. However, the membrane is
not water-permeable and only liquid retardants are
used.
Marshall, Jr. U.S. patent No. 2,997,160,
issued August 22, 1961, discloses a floating
fertilizer package for allowing the slow release of
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fertilizer into a pond but does not disclose or
suggest an aquatic animal-attracting apparatus or
method.
It is an object of the present invention to
provide a method for attracting aquatic animals to a
desired underwater location.
Another object is to provide such method
which uses inexpensive, readily obtainable materials.
A further object is to provide apparatus
for carrying out such method.
It is also an object to provide aquatic
animal-attracting apparatus and a method which will
attract aquatic animals for an extended period
without requiring frequent maintenance or frequent
addition of attractant.
Certain of the foregoing objects can be
accomplished by a method of attracting aquatic
animals to a desired underwater location, which
comprises dissolving an oil-free chemical artificial
bait including a chemical selected from the group
consisting of ammonia, ammonium hydroxide, ammonium
salts, amines, ureas, purines, guanidine, low
molecular weight amino acids and mixtures thereof at
such desired underwater location.
Others of the foregoing objects can be
accomplished by apparatus for attracting aquatic
animals comprising container means, an oil-free
water-soluble chemical artificial bait in the container
means, and means for emitting dissolved bait from the
container means, the chemical artificial bait including
a chemical selected from the group consisting of
ammonia, ammonium hydroxide, ammonium salts, amines,
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ureas, purines, guanidinel low molecular weight amino
acids and mixtures thereof.
Such objects also can be accomplished by a
method of forming an apparatus for attracting aquatic
animals, which comprises forming a quantity of oil-
free chemical artificial bait in the form of a block,
the chemical artificial bait including a chemical
selected from the group consisting of ammonia, ammonium
hydroxide, ammonium salts, amines, ureas, purines,
guanidine, low molecular weight amino acids and mixtures
thereof, applying a covering of liquid resin to the
block and leaving an aperture therethrough, curing the
resin of the covering to water-impermeable condition,
and covering the aperture location with a water-
permeable membrane.
In drawings which illustrate embodiments of
the invention:
Figure 1 is an exploded top perspective of
aquatic animal-attracting apparatus in accordance with
the present invention, and Figure 2 is an elevation of
the aquatic animal-attracting apparatus
of Figure 1 in assembled condition;
Figure 3 is a longitudinal central section
of the assembled aquatic animal-attracting apparatus
of Figure 2;
Figure 4 is a vertical section of a crab
pot having the attracting apparatus of the present
invention installed in it;
Figure 5 is an exploded top perspective
of an alternative form of aquatic animal-attracting
apparatus in accordance with the present invention
without a covering; and Figure 6 is an elevation of
the aquatic animal-attracting apparatus of Figure 5
in assembled condition with a covering applied,
parts being broken away.
In accordance with the present invention,
aquatic animals, such as fish, shrimp, crab or
lobster, are attracted to a desired underwater
location, such as a fish trap or shrimp, crab or
lobster pot, by dissolving at such location ammonia
or an ammonium compound or another derivative of
ammonia. It is preferred that the compound be of a
type which produces ammonium ions when dissolved,
but compounds such as amines producing methylammonium,
diethylammonium, dimethylammonium, triethylammonium
and trimethylammonium cations, for example, also
serve as aquatic animal attractants. Such amines
are, respectively, methylamine, diethylamine,
dimethylamine, triethylamine and trimethylamine.
The preferred animal-attracting compound is ammonium
chloride (NH4CL) because it dissolves rapidly and
because it is readily obtainable and inexpensive.
Further, at normal temperatures ammonium chloride
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is crystalline and crystalline compound is more
compact and easier to handle than a liquid or a
gas. However, other acceptable compounds are: any
other readily soluble ammonium salt; ammonia (liquid
or gas); ammonium hydroxide; amines, including
primary, secondary, tertiary and quaternary amines,
for example methylamine, dimethylamine, trimethylamine
and tetramethylammonium hydroxide, respectively;
ureas such as biuret and thiourea; derivatives of
urea such as guanidine and purines including guanine
and xanthine; and low molecular weight amino acids
such as carbamic acid, glycine, alanine and serine.
Each of the above compounds is "chemical artificial
bait" in that a quantity of any of these compounds
is not normally available as customary food for
aquatic animals and in that pure quantities of such
compounds are produced by chemical, as opposed to
biological, processes.
For attracting Dungeness crab with a
dissolved ammonlum compound, it has been found that
the release rate of dissolved bait should correspond
to the release of 1 to 50 grams of ammonium ions
per day. If the ammonium ion release rate is less
than 1 gram per dayr only crabs in the immediate
area of the release location are attracted. An
ammonium ion release rate of more than 50 grams per
day appears to confuse crabs rather than to attract
them to the release location. It is believed that
the optimum ammonium ion release rate for crab is
11 or 12 grams per day.
In the apparatus for releasing dissolved
chemical artificial chemical bait shown in Figures
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1 through 4, the closed end of a cylindrical container
1 which has circumferential rows of apertures 2
carries an external connection hook 3. The other
end of the container tightly receives the cylindrical
projection of a cap 4. A screen 5 snugly encircles
the container and supports a water-permeable membrane
6 in position covering the container apertures. An
apertured cylindrical shroud 7 is spaced from the
container membrane and screen by an annular flange
8 extending radially inward from the shroud to the
container. Such shroud protects the membrane from
being punctured. Sliding movement of the flange
and shroud lengthwise of the container i5 limited
by screen 5 in one direction and by a stop projection
9, such as a button or rib, in the other direction.
In operation a quantity of water-soluble
chemical artificial bait is sealed within container
1 by cap 4. The container is positioned at a
desired location under water, such as inside a crab
pot. For example, the container connection hook 3
can be secured to the bottom of the pot and a
three-way guy 10 of wire or elastomer material can
secure the cap end of the container to the top of
the pot as shown in Figure 4. The water-permeable
membrane confines the bait against direct exposure
to water in the area of the container. Water
diffuses into the container through membrane 6 and
apertures 2, and the bait is dissolved. The
dissolved bait steadily diffuses out of the container
at a substantially constant rate.
In prior art bait containers such as
disclosed in Muir et al. U.S. patent No. 2,434,220,
the rate at which the bait dissolves is less than
the diffusion rate through the container apertures.
Therefore, the release rate in the prior art
containers is not constant but follows the rate at
which the bait dissolves, which rate is continually
decreasing as the quantity of undissolved bait
decreases. Also, the Muir et al. oil would tend to
clog the pores of a semipermeable membrane, reducing
the release rate of cations through it. Additionally,
the natural oily bait decomposes over time thereby
limiting the length of time it can be stored.
There are several factors which affect
the dissolved bait release rate. The primary
factors are the total area of the container apertures
and the characteristics of the water-permeable
membrane. A suitable membrane is a water-
insoluble, water-permeable cellulose sheet impregnated
with regenerated cellulose approximately .003 inch
(.076 mm) to .004 inch (.102 mm) thick having a
; 20 molecular weight cutoff point of 12,000 to 14,000,
and plasticized with glycerine, such as the membrane
sold by Spectrum Medical Industries, Inc. under the
trademark "SPECTRAPOR 5". If this type of membrane
is used and the bait is ammonium chloride, the
total container aperture area should~be 1/5 square
inch (1.29 sq. cm) to 5 square inches (32.26 sq.
cm) to obtain the desired crab-attracting ammonium
ion release rate range of 1 to 50 grams per day in
sea water. About 2.5 pounds (1.1 kg) of ammonium
chloride sealed within a container having a total
aperture area of approximately 1-1/2 sq. inches
(g.68 sq. cm) will release ammonium ions at the
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preferred rate of 11 to 12 grams per day for about
30 days.
In the preferred embodiment of the present
invention shown in Figures 5 and 6, about 2-1/2
pounds (1.1 kg) of crystalline ammonium chloride is
pressed into an oblong block 10 about 5 inches
(12.7 cm) by 2-1/2 inches (6.4 cm) by 2 inches (5.1
cm). A membrane sleeve 6', which may be a SPECTRAPOR
5 membrane, is slid over the block and snugly
encircles the block central portion. A plastic
screen sheet 5', preferably of a length at least as
great as the major portion of the length of block
10, is wrapped around the block and membrane with
its overlapping margins heat-bonded for forming a
screen lap joint 11 extending lengthwise of the
block. Such screen may be polyester-coated loosely
woven glass fiber.
As seen in Figure 6, a polyurethane
coating 12 is applied to the opposite ends of the
block, such as by brushing, dipping or spraying,
and is allowed to set bonded to the screen and to
the underlying cellulose membrane to form a
"container" having only a single circumferential
"aperture" or slit 13 of screen and membrane exposed
between the container and coverings. Forming the
bait block 10 with rounded edges as shown in Figure
5 helps assure that the coverings will be of
uniform thickness even at the edges of the block.
For attracting crab, the total area of
exposed membrane should fall within the range of
total aperture areas given for the embodiment of
Figures 1 through 4, preferably about 1-1/2 square
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inches (9.68 sq. cm). Such substantially covered
block can be placed in the conventional bait box of
a crab trap, for example, or otherwise retained at
the location to which it is desired to attract
aquatic animals.
The operation of the apparatus of Figures
5 and 6 is substantially identical to the operation
of the apparatus of Figures 1 through 4. As ammonium
chloride is dissolved and ammonium ions are emitted
at a desired substantially constant rate, the
"container" will not collapse or break apart because
the opposite container ends formed by the polyure-
thane coverings 12 are joined by the reinforcing
screen 5' which also at least somewhat protects the
- membrane.
An operable combination of attracting
apparatus features for attracting a particular
aquatic species can be chosen by selecting a readily
water-soluble chemical artificial bait and a water-
permeable membrane, and then determining experimentallythe total aperture area of the container which
achieves the optimum attracting release rate. The
release rate could be decreased by providing a
closely enc~rcling protective shroud having a small
total aperture area. ~lowever, in the embodiment of
Figures 1 through 4, shroud 7 is spaced from the
container and has many apertures so that it does
not appreciably affect the flow of dissolved bait
from the container.
Preferably, the r,lesh of screen 5 or 5' is
large enough that the screen does not appreciably
affect the release of dissolved bait.
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Any combination of membrane, container
aperture area, and shroud spacing and aperture area
which achieves the desired release rate could be
used.
The SPECTRAPOR 5 membrane is preferred
because it is semipermeable and has high wet strength
and resistance to disintegration. Any other cation-
permeable membrane with adequate wet strength and
resistance to abrasive disintegration and with
comparable ion diffusion characteristics would be
suitable.
In the embodiment of Figures 1 through 4,
the container cap, screen, shroud, shroud flange
and stop may all be plastic material such as poly-
vinyl chloride. ~owever, in the embodiment of
Figures 5 and 6, it is important that a strong
watertight bond be formed between the container
coverings, screen and membrane. It has been found
that the filled coating "PR-1654" manufactured by
Products Research and Chemical Corporation forms a
strong watertight bond with the SPECTRAPOR 5
membrane and a Fiberglas screen, such as the Fiberglas
screen material commonly used for window screens,
and also has the advantage of setting or curing
quickly.
The attachment and growth of marine
organisms to the attracting apparatus, and especially
to the membrane, can be prevented by marine growth
retardant. For example, approximately 1 gram of
cuprous oxide or cupric oxide may be mixed with
each 30 day supply of bait.
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If a container having a sufficient quantity
of bait is used, aquatic animals are attracted
continuously throughout an extended period without
servicing the attracting apparatus. A variety of
aquatic animals are attracted, including shrimp,
crab and lobster in sea water, crayfish in fresh
water and various food fish in either sea water or
fresh water. Consequently, the method and/or
apparatus of the present invention can be used to
attract fish to a fish trap or shrimp, crab or
lobster to a pot. In addition, such apparatus
and/or method could be used to attract aquatic
animals to a general area where conventional baits
or lures are present to increase greatly the aquatic
animal-catching effectiveness of commercial or
sport fisheries. Further, conventional lures can
be modified to hold chemical artificial bait and to
release such bait at an appropriate rate to increase
the attracting effectiveness of the lures.
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