A device and method for reducing depredation of fish by sharks

Abstract

It is known to try to use electrical currents passed through seawater to deter sharks from regions of human activity. Such high voltages can be dangerous to operators (e.g. fishermen or fishers) when handling such devices in water. The present invention provides a device with a first electrically-insulated cage (7) disposed around a first electrode (23), and a second electrically-insulated cage (9) disposed around a second electrode, the second cage (9) spaced from the first cage (7). In this way, an operator may be protected from high electrode voltages, while the exterior profile of the device may be maintained as small as possible.

Description

A DEVICE AND METHOD FOR REDUCING DEPREDATION OF FISH BY SHARKS

[0001] The present invention relates generally to a device and a method of reducing depredation of fish by sharks and finds particular, although not exclusive, utility in sport fishing.

[0002] Sharks and other sea creatures, including fish such as rays, are known to depredate (i.e. steal) fish from nets and longlines during the human act of fishing (e.g. for tuna or swordfish).

[0003] Sharks and some other marine species have electroreceptor organs for detecting electric stimuli. In sharks the electroreceptor organs are known as the ampullae of Lorenzini, which are used to detect electric fields that all living things produce. This helps sharks find prey.

[0004] It is known to try to use electrical currents passed through seawater to deter sharks from regions of human activity, particularly around divers. It is not necessary to have currents flowing over long distances surrounding regions to be protected; rather, at large distances, pairs of closely spaced positive and negative electrodes act similar to dipoles emitting an electric field. However, as the electrical field around a dipole decreases at least as fast as the inverse of the cube of the distance from the dipole (rather than the inverse of the square of the distance), it is necessary to use relatively high voltage electrodes in order for the electric field to be detectable by sharks at practical distances.

[0005] As can be appreciated, such high voltages can be dangerous to operators (e.g. fishermen or fishers) when handling such devices, particularly once they have been introduced into the water.

[0006] According to a first aspect of the present invention, there is provided a device for reducing depredation of fish by sharks, the device comprising: a waterproof housing; a power source within the housing; a first electrode disposed on an exterior of the housing; a first electrically-insulated cage disposed around the first electrode; a second electrode disposed on the exterior of the housing, spaced from the first electrode; a second electrically-insulated cage disposed around the second electrode, the second electrically-insulated cage spaced from the first electrically-insulated cage; and a controller powered by the power source and configured to supply an electrical pulse between the first electrode and the second electrode.

[0007] In this way, an operator may be protected from high electrode voltages, while the exterior profile of the device may be maintained as small as possible.

[0008] The waterproof housing may comprise a barrier to water, in particular such that the housing is resistant to the intrusion of water upon submersion at a depth of at least 3m, more particularly at least 10m, for example at least 50m, 500m, 1000m and / or 3000m.

[0009] The power source may comprise an electrochemical cell such as a battery, for example only one (or more than one) AA, AAA, C or D battery.

[0010] The power source may be protected from water by the housing.

[0011] The device may be further configured to activate upon submersion in water.

[0012] The device may further comprise a pair of water contact electrodes (optionally referred to as pins herein) in electrical communication with the controller and which may be arranged to project out of the housing such that water present between the pins completes an electrical circuit causing device to activate. Water between the ends of the pins may be salt water and / or sea water, and optionally may not include freshwater. The device may be configured to deactivate once removed from water, for example when absence of water between the pins breaks the electrical circuit.

[0013] The water contact pins may project out of the housing by less than 5mm, 4mm, 3mm, 2mm and / or 1mm, or may be recessed.

[0014] The first and second electrodes may comprise the water contact pins. That is, the first and second electrodes may be dual purpose, for water detection and pulse emission / reception.

[0015] The controller may comprise a processor and optionally a memory. The controller may be configured to operate in response to a signal indicative of the device being submerged in water, in particular salt water.

[0016] The controller may be electrically connected to the power source.

[0017] The controller may be configured to control supply of electricity to the first and second electrodes from the power source.

[0018] The electrical pulse may comprise applying a voltage difference to the first and second electrodes of between 30 volts and 60 volts, in particular between 40 volts and 50 volts, more particularly approximately 44 volts. Alternatively, the electrical pulse may comprise applying a first voltage to the first electrode and a second voltage (equal but opposite to the first voltage) to the second electrode, wherein the first voltage may be between 30 volts and 60 volts, in particular between 40 volts and 50 volts, more particularly approximately 44 volts.

[0019] The controller may be configured to supply a sequence of electrical pulses between the first electrode and the second electrode, each electrical pulse in the sequence of electrical pulses spaced from each adjacent pulse by between 0.5 and 2 seconds, in particular approximately 1 second.

[0020] The or each electrical pulse may have a duration of between 0.5ms and 10ms, in particular between 1ms and 5ms, for example approximately 1.5ms.

[0021] The or each electrode may comprise a respective electrode surface; that is, a surface arranged to be in contact with sea water when in use, and the remaining parts of that respective electrode may be arranged so as not to be in contact with sea water when in use.

[0022] The first electrode (or electrode surface) may be disposed at a first end of the housing; and the second electrode (or electrode surface) may be disposed at a second end of the housing opposite the first end of the housing. In this way, the distance between the first and second electrodes (or electrode surfaces) can be maximised without excessively increasing the size of the device.

[0023] The first and / or second electrodes (and / or electrode surfaces) may be mounted axially on the housing. In particular, the housing may have an elongate shape.

[0024] The second electrode (or electrode surface) may be spaced from the first electrode (or electrode surface) by between 5cm and 30cm, in particular between 8cm and 20cm, more particularly between 10cm and 15cm, for example approximately 12cm. That is, the centre of one electrode (or electrode surface) may be so spaced, or preferably the periphery of one electrode (or electrode surface) may be spaced from that of the other by such a distance.

[0025] The or each electrode (or electrode surface) may be disposed on an exterior of the housing. The or each electrode (or electrode surface) may be recessed, proud of, or flush with a surface of the housing.

[0026] The or each electrode may extend through the housing by virtue of an interference fit to prevent water ingress. For instance, at least 5N of force may be required to located them within respective holes in the housing (or portions of the holes), in particular at least 20N, more particularly at least 30N, 50N or 70N; alternatively and / or additionally, the or each electrode may be glued or otherwise sealed within the respective holes (e.g. by rubber tubing or with O-rings).

[0027] The electrode may comprise graphite, titanium, brass, copper, a mixed metal oxide coating, or any combination or sub-combination thereof. The electrode may comprise a disc, plate, cylinder or rod.

[0028] The or each cage may comprise an enclosure comprising a plurality of elongate members extending from the housing around a periphery of one electrode (or electrode surface). The plurality of elongate members may comprise between three and twelve elongate members, in particular between five and ten, more between six and nine elongate members, for example seven or preferably eight.

[0029] The elongate members may be spaced to allow flow of water therebetween. At least one part of any pair of adjacent elongate members may be spaced by at least 3mm, more particularly 5mm, in particular at least 7mm. The elongate members may be arranged to prevent air bubbles from residing within the cage.

[0030] The elongate members may be spaced to prevent a child's or an adult's finger passing therebetween. No part of any pair of adjacent elongate members may be spaced by less than 12mm, in particular 10mm, more particularly8mm.

[0031] Each elongate member may comprise a fin having a length extending away from the housing, a depth extending toward an axis of the device and / or electrode (and / or electrode surface), and a width extending around the axis of the device and / or electrode (and / or electrode surface), respectively.

[0032] The length of each elongate member may be significantly greater than its depth, and / or its depth may be significantly greater than its width. In this context, the word "significantly" is taken to mean "at least two times", in particular "at least three times", more particularly "at least four times"

[0033] Each cage may have a dome shape. The elongate members of the first and / or second cage may form a respective first and / or second dome.

[0034] The or each cage may surround the respective electrode (or electrode surface). In particular, the or each cage may, in combination with the housing, entirely surround the respective electrode (or electrode surface).

[0035] Each elongate member may comprise electrically-insulating material, such as a plastics material. In particular, each elongate member may be composed entirely of electrically-insulating material. In this way, an adult's finger may not access the electrode within the or each cage; however, electrical current may flow through the or each cage via the water, when in use.

[0036] The first cage may be disposed at a first end of the housing; the second cage may be disposed at a second end of the housing opposite the first end of the housing. In this way, the distance between the first and second cages can be maximised without excessively increasing the size of the device.

[0037] The first and / or second cages may be mounted axially on the housing. The first and / or second cages may be axially rotationally symmetric.

[0038] The second cage may be spaced from the first cage by between 5cm and 30cm, in particular between 8cm and 20cm, more particularly between 10cm and 15cm, for example approximately 12cm. That is, the centre of one cage may be so spaced, or preferably the periphery of one cage may be spaced from that of the other by such a distance.

[0039] The device may be configured such that an electrical current caused by the pulse passes out of the first electrically-insulated cage before passing into the second electrically-insulated cage, when submerged in water.

[0040] In use, a voltage measured on an external periphery of the cage may be at most two-thirds of a voltage measured on the respective electrode surface, in particular at most one-half, more particularly at most one-third. For example, for an electrode potential of 44 volts the potential external to the cage may be 14.6 volts.

[0041] A respective line attachment eye may be provided on the first and / or second cage. In this way, the device may be attached to a fishing at one or both ends.

[0042] The or each eye may comprise a hope, loop and / or through-hole in a support structure. The or each eye may comprise metal.

[0043] The or each eye may be mounted on the first and / or second dome or the first and / or second cage, respectively.

[0044] The or each eye may be mounted axially on the respective cage. In this way, turning forces about the eye may be minimised.

[0045] The or each eye may be configured to be rotatably connected to the respective cage. In this way, if water flow causes the device to twist the line does not become tangled. The or each eye may form part of a respective swivel.

[0046] The or each eye may comprise a female portion and a male portion releasably insertable therein, and configured to form a neck for rotatably engaging with the respective cage.

[0047] According to a second aspect of the present invention, there is provided a system for reducing depredation of fish by sharks, the system comprising: the device of the first aspect; and a line attached thereto.

[0048] According to a third aspect of the present invention, there is provided a method of reducing depredation of fish by sharks, the method comprising the steps of: providing the device of the first aspect; submerging the device in water; and supplying an electrical pulse between the first electrode and the second electrode.

[0049] The above and other characteristics, features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. This description is given for the sake of example only, without limiting the scope of the invention. The reference figures quoted below refer to the attached drawings.

[0050] is a plan view of a device for reducing depredation of fish by sharks.

[0051] is a plan view of one end of the device of.

[0052] is a cutaway view of the end of the device of.

[0053] is a cross-sectional view of the end of the device of.

[0054] is an exploded view of a swivel used in the device of figures 1 to 4.

[0055] The present invention will be described with respect to certain drawings but the invention is not limited thereto but only by the claims. The drawings described are only schematic and are non-limiting. Each drawing may not include all of the features of the invention and therefore should not necessarily be considered to be an embodiment of the invention. In the drawings, the size of some of the elements may be exaggerated and not drawn to scale for illustrative purposes. The dimensions and the relative dimensions do not correspond to actual reductions to practice of the invention.

[0056] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequence, either temporally, spatially, in ranking or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that operation is capable in other sequences than described or illustrated herein. Likewise, method steps described or claimed in a particular sequence may be understood to operate in a different sequence.

[0057] Moreover, the terms top, bottom, over, under and the like in the description and the claims are used for descriptive purposes and not necessarily for describing relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that operation is capable in other orientations than described or illustrated herein.

[0058] It is to be noticed that the term “comprising”, used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression “a device comprising means A and B” should not be limited to devices consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the device are A and B.

[0059] Similarly, it is to be noticed that the term “connected”, used in the description, should not be interpreted as being restricted to direct connections only. Thus, the scope of the expression “a device A connected to a device B” should not be limited to devices or systems wherein an output of device A is directly connected to an input of device B. It means that there exists a path between an output of A and an input of B which may be a path including other devices or means. “Connected” may mean that two or more elements are either in direct physical or electrical contact, or that two or more elements are not in direct contact with each other but yet still co-operate or interact with each other. For instance, wireless connectivity is contemplated.

[0060] Reference throughout this specification to “an embodiment” or “an aspect” means that a particular feature, structure or characteristic described in connection with the embodiment or aspect is included in at least one embodiment or aspect of the present invention. Thus, appearances of the phrases “in one embodiment”, “in an embodiment”, or “in an aspect” in various places throughout this specification are not necessarily all referring to the same embodiment or aspect, but may refer to different embodiments or aspects. Furthermore, the particular features, structures or characteristics of any one embodiment or aspect of the invention may be combined in any suitable manner with any other particular feature, structure or characteristic of another embodiment or aspect of the invention, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments or aspects.

[0061] Similarly, it should be appreciated that in the description various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Moreover, the description of any individual drawing or aspect should not necessarily be considered to be an embodiment of the invention. Rather, as the following claims reflect, inventive aspects lie in fewer than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

[0062] Furthermore, while some embodiments described herein include some features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form yet further embodiments, as will be understood by those skilled in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0063] In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practised without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

[0064] In the discussion of the invention, unless stated to the contrary, the disclosure of alternative values for the upper or lower limit of the permitted range of a parameter, coupled with an indication that one of said values is more highly preferred than the other, is to be construed as an implied statement that each intermediate value of said parameter, lying between the more preferred and the less preferred of said alternatives, is itself preferred to said less preferred value and also to each value lying between said less preferred value and said intermediate value.

[0065] The use of the term “at least one” may mean only one in certain circumstances. The use of the term “any” may mean “all” and / or “each” in certain circumstances.

[0066] The principles of the invention will now be described by a detailed description of at least one drawing relating to exemplary features. It is clear that other arrangements can be configured according to the knowledge of persons skilled in the art without departing from the underlying concept or technical teaching, the invention being limited only by the terms of the appended claims.

[0067] is a plan view of a device for reducing depredation of fish by sharks, the device comprising a waterproof housing 1 comprising a body 3, and a cap 5 threadedly connected to the body 3 to form a waterproof seal therebetween.

[0068] At opposing ends of the housing 1 are provided a pair of electrodes (not shown), each recessed into the waterproof housing 1. Around each electrode extends a respective cage 7, 9 surmounted by a respective line attachment eye 11, 13.

[0069] is a plan view of one end of the device of. Reference signs will be used corresponding to the upper end of, but it is to be understood that these apply to the lower end, mutatis mutandis.

[0070] Eight fins 15 (five of which are shown) project upwardly from the cap 5 to form a dome shape with spaces 17 therebetween to allow flow of water to the electrode (not shown). At the top of the dome, the eye 11 is mounted within a collar 19. The eye 11 is provided with a through hole 21.

[0071] is a cutaway view of the end of the device ofshowing the electrode 23 recessed below an uppermost portion of the cap 5. The eye 11 forms part of a swivel 25 that extends through the collar 19 by virtue of narrow neck 27, before terminating with a laterally extending head portion 29. The combination of narrow neck 27 and larger head portion 29 below and eye 11 above holds the swivel with the collar 19, within which it is free to rotate.

[0072] is a cross-sectional view of the end of the device of, showing the swivel 25 in cross-section, in particular. The swivel 25 is formed from a female part composed of the eye 11 and the neck 27, having an internally-threaded axial bore 31 therein, and a male part composed of the head portion 29 and an externally threaded shank 33, threadedly mated with the axial bore 31. A screw drive 35 is provided in the head portion 29.

[0073] is an exploded view of a swivel 25 used in the device of figures 1 to 4, showing the eye 11, neck 27 and axial bore 31 of the female part, and the head 29, shank 33 and screw drive 35 of the male part.

Claims

A device for reducing depredation of fish by sharks, the device comprising:a waterproof housing;a power source within the housing;a first electrode disposed on an exterior of the housing;a first electrically-insulated cage disposed around the first electrode;a second electrode disposed on the exterior of the housing, spaced from the first electrode;a second electrically-insulated cage disposed around the second electrode, the second electrically-insulated cage spaced from the first electrically-insulated cage; anda controller powered by the power source and configured to supply an electrical pulse between the first electrode and the second electrode.The device of claim 1, wherein the controller is configured to supply a sequence of electrical pulses between the first electrode and the second electrode, each electrical pulse in the sequence of electrical pulses spaced from each adjacent pulse by between 0.5 and 2 seconds.The device of claim 2, wherein each electrical pulse has a duration of between 0.5ms and 10ms.The device of any preceding claim, wherein the first electrode is disposed at a first end of the housing; and the second electrode is disposed at a second end of the housing opposite the first end of the housing.The device of any preceding claim, wherein the first cage comprises an enclosure comprising a plurality of elongate members extending from the housing around a periphery of one electrode.The device of claim 5, wherein each elongate member comprises a fin having a length extending away from the housing, a depth extending toward an axis of the device, and a width extending around the axis of the device, and wherein for each fin the length is at least two times greater than the depth, and the depth is at least two times greater than the width.The device of any preceding claim, further comprising a first line attachment eye on the first cage.The device of claim 7, wherein the first eye may be mounted axially on the first cage.The device of claim 7 or claim 8, wherein the first eye is configured to be rotatably connected to the fist cage.The device of claim 9, wherein the first eye comprises a female portion and a male portion releasably insertable therein, and the first eye is configured to form a neck for rotatably engaging with the first cage.A system for reducing depredation of fish by sharks, the system comprising:the device of any preceding claim; anda line attached thereto.A method of reducing depredation of fish by sharks, the method comprising the steps of:providing the device of any one of claims 1 to 10;submerging the device in water; andsupplying an electrical pulse between the first electrode and the second electrode.

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