GB2178932A - Lobster and fish trap - Google Patents

Abstract

A lobster or fish trap comprises a trap body 11, an elongate line 13 attached to the trap body, a spool or the like 12 for storing the line, and a flotation device 14 attached to the line distal to the point of attachment of the line to the trap. The flotation device 14 is arranged in relatively close proximity to the trap body and is remotely actuable to render it buoyant and/or release it from its position in close proximity to the trap. Float 14 comprises lay-flat hose within which is a gas-cylinder 27 with control valve 27 operable by means 15 which includes a battery, radio signal receiver and a switch operable on receipt of a signal to connect valve 27 with the battery. Retrieval apparatus for use with lobster or fish trap is also claimed. <IMAGE>

Description

SPECIFICATION Lobster and fish trap The present invention relates to traps and nets for marine animals including fish, crayfish, rock lobsters, crabs and the like, which traps are hereinafter called lobster and fish traps, and to retrieval apparatus for such lobster traps.

Traditionally lobster traps are formed of solid materials, commonly steel wire and wicker work. These traps are denser than water and when thrown into the water they sink to the bed of the body of water into which they are thrown. In order to render the traps retrievable the traps are conventionally attached to one end of a rope or similar line longer than the depth of the water into which the trap is being thrown and a float is attached to the other end of this line. The trap is retrieved by grappling the float and hauling in the line.

This technique suffers from a considerable number of disadvantages. The presence of a float permanently floating on the surface of the water indicates the presence of a trap and invites theft of the trap and/or its contents. The length of rope or other line must, in practice, be longer than the actual depth of water in which the trap is placed. In calm waters a 25% excess is sufficient but in rougher water this may need to be increased to as much as 50%. As the length of the rope increases so the size of float needed to support it increases. Unfortunately as the size of the float and/or the length of the rope increases so does the tendency of the float and rope to cause the attached trap to lift and drop due to wave or tide or current action which tends to stop marine animals from entering the trap.

It is common practice in deep water to interconnect three or four traps and to connect a float and rope to only the leading one of them. The leading trap tends to secure no catch due to movement of same however it dampens the movement of the other traps and they secure a catch. This practice is however wasteful of capital expenditure. It has also been found that the raising and dropping of a trap due to wave tide or current action on the float and/or rope can cause the trap to "walk". Traps are frequently found considerable distances from the position in which they were dropped. Apart from the physical translocation of the trap due to this "walking" there is also the problem that movement of the trap can result in the trap or the rope becoming tangled with rocks or weeds or of the rope abrading against rocks. In any of these circumstances traps may be lost.Similarly if traps "walk" into deeper water the trap may again be lost as the float becomes submerged when the water depth exceeds the length of the rope.

The permanent positioning of a float on the surface above a trap has the further disadvantage that if the float is run over by a boat the rope can foul the propeller of the boat, the rope can be cut by the propeller or the float holed. In any one of these cases the means for retrieval of the trap is rendered inoperative and the trap is lost.

More recently it has been proposed to provide means for the automatic raising of lobster traps without the use of ropes. In Australian patent specification 496,287 is described a device for automatically raising lobster traps from beneath the water surface comprising a compressed gas, a buoyant means, a control valve to allow gas to pass from the gas container to the buoyant means to displace water and an electrical circuit activated by a signal transmitted through the water in which the trap is located to actuate the control valve. The buoyancy means is described as preferably comprising one or more compartments formed in one or more members from which the trap is formed.

This more recent innovation has the disadvantage that separate buoyant means are required for each trap.

It has also been suggested that because of this, and because the number of individual codes by which the valve means may be addressed is, in practice, limited, a fisherman is forced to raise a large number of his traps in one location simultaneously. This has the problem that some traps may be swept away by wave or current action before the fisherman is able to retrieve them.

They may also be run over by the retrieving boat and thereby lost.

It should be realised that the loss of a lobster trap represents to the fisherman not only the capital cost of the trap but also the time, fuel and other overheads associated with baiting and laying the trap and seeking to find and recover the trap, and in addition the loss of the catch itself. It will therefore be seen than any increase in the reliability of retrieval of lobster pots is of significant commercial importance.

In one aspect the present invention consists in a retrieval apparatus for lobster or fish traps (as hereinbefore defined) comprising means for connection of the apparatus to a lobster or fish trap, an elongate line attached to the connection means, line storage means to store the line on or adjacent the connection means such that the line may be readily removed therefrom, flotation means attached to the line distal to the point of attachment of said line to the connection means, said flotation means being held in relatively close proximity with the connection means and remotely actuable means to render the flotation means buoyant and/or to release the flotation means from being held in close proximity with the connection means.

Another aspect of the present invention consists in a retrievable lobster or fish trap (as hereinbefore defined) comprising a trap body, an elongate line attached to the trap body line storage means to store the line on or adjacent the trap body such that the line may be readily removed therefrom, flotation means attached to the line distal to the point of attachment of said line to the trap body, said flotation means being held in relatively close proximity with the trap body and remotely actuable means render the flotation means buoyant and/or to release the flotation means from being held in close proximity to the trap body.

The arrangement according to the present invention has a combination of the advantages of the prior art systems while avoiding many of their disadvantages.

The retrieval apparatus and traps according to this invention may be coupled with conventional lobster traps so that a single flotation means and rope may be used to raise a plurality of traps. A concomitant advantage is that each group of coupled traps may be actuated by a separate and unique acutation signal.

Thus a single float at a time has to be retrieved thereby further diminishing the chance of traps being lost. The fact that the flotation means remains in close proximity to the trap until the remotely actuable float release and/or actuation means are actuated alleviates the "walking" problems inherent in the conventional system in which a float is permanently on the water surface while the trap is in use.

Apparatus according to this invention may comprise retrieval apparatus to which a conventional lobster trap may be connected or may comprise a trap itself with which the retrieval apparatus is formed integrally. A trap body of a trap according to the present invention may be of any conventional shape or configuration and formed of conventional materials such as metal wire or strip and cane or wicker work or wire mesh.

The exact shape or construction of the trap body is not significant insofar as the present invention is concerned.

The line according to the present invention preferably comprises a rope of a natural or synthetic plastics material however other constructions could alternatively be used. Ideally the line has a slight negative buoyancy and requires to be of a suitable length and of a cross-sectional area allowing that length of line to be conveniently stored in or on the storage means.

The line storage means may comprise any suitable means such as a tray, spool or hook on which the line may be laid or coiled such that upon release of the float, or upon the rendering buoyant of the float, the line will feed freely and smoothly off the line storage means. In a preferred embodiment of the invention the line storage means preferably comprises an annular U-section spool surrounding the trap body or, alternatively, on the periphery of the connection means. The line may be coiled into the spool prior to the trap being used.

The flotation means may comprise a body which is partially buoyant or a body which may be rendered buoyant such as by being inflated with a gas. In a preferred embodiment of the invention the flotation means comprises a length of a collapsible tube closed at one end and connected at the other to the line. A container of a compressed gas is retained within the tube adjacent to the open end of said tube and is connected to a gas conveying duct to convey gas released from the container to the closed end of the tube. Upon opening of the gas container gas is introduced into the tube through the duct. As the tube inflates, it tears away from a releasable means holding the tube on the trap e.g., a strip of "Velcro" (registered trade mark), and begins to rise, initially from the closed end into which the gas is introduced.When the tube is full of gas any excess will bubble out of the lower, open, end of the tube. Similarly as the tube rises in the water, the water pressure on the tube will decrease allowing the gas to expand. The excess expanded gas will also bubble out of the open end of the tube.

The apparatus essentially includes remotely actuable means to render the flotation means buoyant and/or to release the flotation means from its relatively close coupling with the apparatus. In the event that the flotation means is partially buoyant the float release means may comprise a catch, clip or the like remotely actuable to release its engagement with the flotation means and thus allow it to rise. The catch, clip or the like may be directly connected to the float by a short strop or it may be connected to the line, or a loop therein, closely adjacent the float. The essential thing is that the float is connected sufficiently close to the apparatus that the disadvantages of having a float on the water surface are avoided.

In the alternative embodiment in which the flotation means must be rendered buoyant the float activation means may comprise a remotely actuable mechanism to release gas from a container containing a compressed gas as has been described above. Such remotely operable valves are known and are not in themselves the subject of this application.

The remote actuation of the float release and/or actuation means is preferably achieved by an operator transmitting a sonar or radio signal which is received by the float release and/or actuation means. Other types of signals such as acoustic signals and the like could also be used. The signal receiving device is preferably powered by a D.C. battery which also powers the mechanism which is actuated by the signal whether it be a valve or a release clip or the like. The mechanism is most preferably a solenoid which opens a gas valve or opens a release clip or the like.

Hereinafter given by way of example are preferred embodiments of the present invention described with reference to the accompanying drawings in which: Figures la and 1b are respectively a plan view and a vertical sectional view along A-A of Figure 1 a of a lobster trap according to this invention; Figures 2a and 2b are respectively a plan view and a vertical sectional view along A-A of Figure 2a of an apparatus for retrieval of lobster traps according to the present invention; Figure 3 is a side elevational view of an inflatable float for use in conjunction with either the lobster trap of Figure 1 a or the apparatus of Figure 2a.

The lobster trap 10 of Figures la and 1 b comprises a circular lobster trap body 11 made from steel mesh, overlaying a steel frame a U-section circular spool generally indicated by numeral 12 extending about the trap body, a rope 13 connected at one end to the trap body 11 wound around the trap body 11 on the spool 12, a float 14 connected to the other end of the rope 13 and radio signal actuable means 15 to initiate inflation of an inflatable float The lobster trap body 11 has a flat bottom 16 and a separable iid 17, which includes, at a trap entrance 18.

In this respect the trap according to this invention is conventional. The base 16 of trap body 11 is extended to form the lower annular wall 19 of the U-section circular spool 12. The base of the spool 12 is formed by an outer wall of the trap body 11. An upper annular wail 21 is formed to project radially outwardly from the trap body 11 and to diverge outwardly from lower wall 19.

An eye 22 is formed on the base 16 of the trap body 11 to allow the connection of the trap 10 to other traps without flotation means so that a single flotation means may be used to retrieve a number of lobster traps.

The rope 13 is tied at one end to the trap body 11 and is wound around the spool 12. The length of the rope will depend upon the depth of water in which the trap 10 is to be placed however for lobster fishing off Western Australia a typical rope length of up to 220 metres might be used. The other end of the rope 13 is connected to the float 14. The collapsible tube of float 14 comprises a length of a distinctively coloured e.g., yellow or orange, lay-flat hose 20 of the nylon reinforced type. The length of hose can vary according to the desired buoyancy of the float, however, lengths of from 5 to 6m have been found suitable of hose having a 75mm nominal internal diameter.

Referring to Figure 3 it can be seen that the upper end of the hose 20 is closed while the lower end thereof is formed with eyelets 23 through which is inserted a shackle 24 connected to the rope 13. An opening 25 is formed in the wall of the hose 20 about 450mm from the eyelets 23. A compressed air or gas cylinder 26 is retained in the bottom of the hose between the opening 25 and the eyelets 23. The opening 25 allows access to the cylinder 26 and to a valve 27 and an 8mm l.D. gas duct 28 positioned within the hose 20 adjacent the opening 25. The valve 27 is connectible to cylinder 26 and is operable by the radio signal actuable means 15 (See Figure la) to allow gas to flow from cylinder 26 through gas duct 28 into the hose 20. The gas duct 28 extends along the length of hose 20 to the closed end thereof where it terminates in an open end 29.A plurality of holes of 5-6mm diameter are formed at intervals of about 50mm along the length of gas duct 28.

The radio signal actuable means 15 comprises a battery and radio signal receiver as well as a switch.

Upon receipt of an appropriate signal the receiver actuates the switch which directs a current from the battery to the valve 27 to which it is connected.

In use a fresh gas cylinder is inserted in the lower end of the hose and the rope 13 is coiled on the spool 12 with the hose 20 coiled over the rope 13 in a flattened state. The hose is held in position on the trap 10 by a piece of stick-rip material such as "Velcro" (Registered Trade Mark) or the like. The wires connecting the radio signal received 15 are then connected to valve 27 and the trap is ready to be thrown into the sea for use.

When the lobster trap 10 is to be recovered a signal is transmitted from a boat, or similar recovery means, which will actuate the signal actuate means to open the valve 27 and release gas from the cylinder 26 into the hose 20. The hose 20 will straighten and break free from its stick-rip coupling to the trap 11 and float free causing rope 13 to start unreeling from spool 12. Any excess gas in the hose 20 will be vented through opening 25 as the hose rises towards the surface of the water. On reaching the water surface an upper end portion of the hose will lie along the water surface and act as a visible indication of the location of the trap 10.

The lower end of the hose 20 will hang vertically due to the weight of the gas cylinder and the rope and will thereby retain gas in the hose for a long period.

The apparatus and traps shown in Figures 2a & 2b are essentially similar to the trap 10 described with reference to Figures 1 a and 1 b and identical numbering has been given to similar integers in the other embodi ments of the invention. These embodiments are only described insofar as they differ from the embodiment of the invention described with reference to Figures 1 a and 1 b.

The apparatus shown in Figures 2a and 2b is adapted to be connected respectively to conventional lobster traps. In Figures 2a and 2b it will be seen that the base 16 is separate from the trap body 11 and is connectable thereto by wire or other suitable clips. The spool 12 comprises an annular wall 30 which surrounds the trap body 11 and forms the base of the spool. Base 1 6, annular wall 30 and spool 12, form the connection means between the line 13 and the trap 10 for this embodiment. Upper and lower side walls 19 and 21 are connected to wall 30 and extend radially therefrom.

It will be recognised by persons skilled in the art that numerous variations and modifications may be made to the invention as described above without departing from the spirit or scope of the invention as broadly described.

Claims (1)

1. A retrieval apparatus for lobster or fish traps (as herein before defined) comprising: means for connection of the apparatus to a lobster trap, an elongate line attached to the connection means, line storage means to store the line on or adjacent the connection means such that the line may be readily removed therefrom.

flotation means attached to the line, distal to the point of attachment of said line to the connection means, said flotation means being held in close proximity with the connection means, and remotely actuable means to render the flotation means buoyant and/or to release the flotation means from being held in relatively close proximity to said connection means, 2.A retrievable lobster or fish trap (as hereinbefore defined) comprising: a trap body, an elongate line attached to the trap body, line storage means to store the line or an adjacent the connection means such that the line may be readily removed therefrom, flotation means attached to the line, distal to the point of attachment of said line to the trap body, said flotation means being held in close proximity with the trap body, and remotely actuable means to render the flotation means buoyant and/or to release the flotation means from being held in relatively close proximity to said trap body.

3. An apparatus or a lobster or fish trap according to either claim 1 or claim 2 wherein said remotely actuable means comprises: a remote signal receiver to detect an actuating signal, an electrical source to provide electrical current in response to said signal receiver receiving an actuating signal and a mechanism, powered by said electrical current to render buoyant and/or release said flotation means.

4. An apparatus or a lobster or fish trap according to claim 3 wherein said flotation means is adapted to be rendered buoyant by said remotely actuable means by gas inflation.

5. An apparatus or a lobster or fish trap according to claim 4 wherein an increase volume of said flotation means due to inflation of same releases said flotation means from the connection means or trap body.

6. An apparatus or a lobster or fish trap according to claim 5 wherein said flotation means is coupled to the connection means or trap body by a coupling which comprises stick-rip material having complementary parts attached to the flotation means and to the connection means or trap body.

7. An apparatus or a lobster or fish trap according to any one of claims 3, 4, 5 or 6 wherein said flotation means comprises: a collapsible elongate tube, said elongate tube having a first sealed end, a second unsealed end, said unsealed end being connected to said line, an opening being provided in said collapsible elongate tube at a point between said first and second ends thereof, a compressed gas cylinder retained within said collapsible tube proximal to said second end of said tube, and a duct providing gas communication between said compressed gas cylinder and said first end of said tube,

9. An apparatus or a lobster or fish trap according to claims 8 wherein said mechanism comprises a solenoid activated valve on said gas cylinder, 10. An apparatus or a lobster or fish trap according to either claims 8 or 9 wherein said collapsible tube is made from nylon reinforced hose,

11. An apparatus or a lobster or fish trap according to claim 8, 9 or 10 wherein said duct includes holes spaced along the length thereof to aid rapid inflation of said tube.

12. An apparatus or a lobster or fish trap according to any one of the preceding claims wherein said actuating signal is a radio signal.

13. An apparatus or a lobster or fish trap as hereinbefore described with reference to Figures la and 1 b or Figures 2a and 2b or Figure 3 of the accompanying drawings.