Abstract:
A corral for fish, the corral comprising: at least one wall that defines a pathway along which fish are able to travel wherein the pathway is inwardly winding.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to a corral for fish and associated fish accumulator . In particular, the invention relates to assisting in preventing undue stress in the fish during the harvest and transfer process to produce high yielding fish flesh and improve the efficiency of the harvest process. 
       BACKGROUND OF THE INVENTION 
       [0002]    The harvesting of fish is a complex process. One popular manner in which fish are humanely harvested is to capture fish through the use of a net, passing the fish into a distribution table using a fish pump and then stunning and bleeding the fish using a mechanical fish stunning machine. The distribution tank and mechanical fish stunning machine are shown in PCT/AU2003/01615 by the same applicant. 
         [0003]    Farmed and wild fish are harvested using nets which are drawn in or “seined” to crowd the fish to a high density. The fish are then sucked through a funnel which is placed in the midst of the “seined” fish. The seining process relies on the progressive tightening of the nets to increase the density of the fish in the nets in order to maintain a desired harvest rate. 
         [0004]    This seining process often results in high stress and activity in the fish being harvested. As a result, the oxygen consumption by the fish typically increases exhausting the available oxygen supply and the energy reserves of the fish resulting in the production of lactic acid in the fish muscle. If this lactic acid does not dissipate before the fish is stunned, then quality of the fish flesh is diminished, which results in a smaller yield. If the fish are crowded severely in the seine there will be issues of fish welfare and some of the fish may die prior to harvesting making them unacceptable for processing and resulting in a net loss. Furthermore the dead and stressed fish can cause blockages in the harvest system and/or may cause the fish to be incorrectly oriented in automated harvest systems. 
         [0005]    Once the fish pass from the nets through a funnel, they pass into a fish accumulator. The distributor includes a tank in which the fish are accumulated after they pass out of the net. The fish are then passed from the tank of the fish accumulator into a pipe that leads to the distribution table. The fish accumulator is connected to a vacuum—pressure pump which draws air from the tank and as a result water and fish into the accumulator tank. Fish are expelled from the fish accumulator by applying air to the tank increasing the pressure and causing the fish and water to pass out of the fish accumulator into the pipe and subsequently to the distribution table. 
         [0006]    Unfortunately it is an instinctive nature of most fish to swim against any current that is created. Accordingly, when fish are sucked from the net through the funnel they turn and try and swim away from the funnel. Even when the fish are within a pipe that transports them to the fish accumulator the fish swim against the current. Similarly, when the fish are being transported from the fish accumulator to the distribution table, the fish swim against the current that is developed. 
         [0007]    In both instances this can cause the fish swim strenuously to avoid the exiting water current and result in lactic acid build up within the fish which can in reduce flesh quality. Further, most fish will travel backwards down the pipes. When travelling backwards down the pipe the fish are vulnerable to injury as the edges of the fins and operculum (“gill covers”) and can become caught on any internal imperfections of the pipes especially adjacent pipe joins or bends. If the operculum is caught it can become folded back rupturing muscles and/or damaging gills which an cause severe stress and/or bleeding. Furthermore the fish travels much more slowly through the pipe as a result of the fish&#39;s action in swimming against the flow of water in the pipe as so remains in the pipes for a much longer time than if travelling forward in the flow. 
         [0008]    The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge in Australia. 
       OBJECT OF THE INVENTION 
       [0009]    It is an object of the invention to overcome or alleviate one or more of the disclosures or provide the consumer with the useful or commercial choice. 
       SUMMARY OF THE INVENTION 
       [0010]    In one form, although not necessarily the only or broadest form, the invention relates to a corral for fish, the corral comprising: 
         [0011]    at least one wall that defines a pathway along which fish are able to travel; 
         [0012]    wherein the pathway is inwardly winding. 
         [0013]    An enclosure may surround the at least one wall. Alternatively, the at least one wall may form part of the enclosure. 
         [0014]    An entrance may form part of the enclosure to allow fish access to the pathway. 
         [0015]    Preferably the at least one wall is in the form an inward spiral. Accordingly, the pathway may also be at least in the shape of an inward spiral. 
         [0016]    Normally, the pathway directs the fish to a middle of the enclosure. Preferably, the pathway directs the fish toward a centre of the pathway. 
         [0017]    The at least one wall may also contain at least one return. The return may be stepped outwardly from the pathway. The return may be arcuate in shape. 
         [0018]    The at least one wall may also contain at least one gate. Normally there are a plurality of gates. The gates may be pivotally movable between an open position and a closed position. The gates may form part of the wall when in the closed position. The gates may change the pathway when in an open position. That is, the gates may extend between parts of a wall or between two walls when in the open position. 
         [0019]    In another form, the invention resides in a fish accumulator for distributing fish, the fish accumulator comprising: 
         [0020]    a tank; 
         [0021]    a entrance in fluid communication with the tank; 
         [0022]    an exit in fluid communication with the tank; and 
         [0023]    at least one water rotation device to cause water to rotate water within the tank. 
         [0024]    The tank is typically substantially cylindrical in shape. Accordingly, the tank normally has two tanks ends and arcuate tank side wall. The tank may be made from a material that is transparent to view fish located within the tank. This may include the tank ends and/or tank side wall. Alternatively the tank may include at least one viewing window. 
         [0025]    The entrance is typically located adjacent to one end of the tank. The entrance is typically orientated substantially tangentially with respect to the tank side wall. That is, the entrance is orientated to direct water into the tank to assist in rotating the water. 
         [0026]    A fish guide may be associated with the entrance. The guide may be in the form a helix or screw. Preferably, the fish guide is in the form of a helical platform. 
         [0027]    The exit is typically located adjacent to one end of the tank. The exit is typically located adjacent an opposite end of the tank compared to the entrance. The exit is typically orientated substantially tangentially with respect to the tank side wall. 
         [0028]    The exit and the entrance are orientated in a similar manner. That is, the location at which the entrance joins the tank and the location at which the exit joins the tank are in longitudinal alignment. It would be appreciated by a person skilled in the art that the orientation of the exit and the entrance may be varied in accordance with design. For example the location at which the entrance joins the tank and the location at which the exit joins the tanks may be at 45, 90, 135, 180, 225, 270 or 315 degrees with respect to each other. 
         [0029]    The entrance may be aligned to correspond to the orientation of the rotation of the water within the tank and the exit may be aligned opposite to the orientation of said water rotation. 
         [0030]    The at least one rotation device may include any device that causes the water to rotate in a single direction. For example, the water rotation device may be the positioning of the entrance tangentially so that the water within the tank rotates. Similarly the water rotation device may be the helix. 
         [0031]    Another rotation device may include a water rotation inlet which directs water into the tank. The water rotation inlet may be orientated substantially tangentially with respect to the tank side wall. 
         [0032]    Yet another rotation device may include an spinning member such as impellor, propeller or the like device. 
         [0033]    The rotation device may rotate water in the same direction as a direction of the helix. 
         [0034]    A vacuum/pressure inlet may be fluidly connected to a pump. The vacuum/pressure inlet may be orientated longitudinally with respect to the tank. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0035]    Embodiments of the inventions, by way of example only, will now be described with reference to the accompanying figures in which: 
           [0036]      FIG. 1  is a perspective view of a fish corral according to an embodiment of the invention; 
           [0037]      FIG. 2  is a further perspective view of the fish corral of  FIG. 1  according to an embodiment of the invention; 
           [0038]      FIG. 3  is a perspective view of an fish accumulator according to an embodiment of the invention; 
           [0039]      FIG. 4  is a top view of the fish accumulator of  FIG. 3  according to an embodiment of the invention; 
           [0040]      FIG. 5  is a front view of the fish accumulator of  FIG. 3  according to an embodiment of the invention; and 
           [0041]      FIG. 6  is a side view of the fish accumulator of  FIG. 3  according to an embodiment of the invention; 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0042]      FIGS. 1 and 2  show a corral  10  which is used in the harvesting of fish. The corral  10  is constructed from netting. The size of the netting may be varied according to the species and/or size of fish that is to be harvested. It should be appreciated that other types of materials may be used other than netting. 
         [0043]    The corral  10  is formed from an enclosure  20  in which is located a single wall  30 . The enclosure  20  includes a base  21  and series of upstanding barriers  22 . An entrance  24  is located between the barriers  22 . It should be appreciated that the size and shape of the enclosure  20  may be varied according to design requirements. 
         [0044]    The wall  30  extends upwardly from the base  21  of the enclosure  20 . The wall  30  is in the form of a spiral and accordingly is inwardly winding. A pathway  40  is created by the wall  30  in which fish are able to follow. The pathway  40  extends from the entrance  24  of the enclosure  20  to a termination of the inward winding of the spiral wall  30 . The termination of the inward winding of the spiral wall  30  is adjacent the centre of the enclosure  20 . 
         [0045]    The wall  30  includes three gates  31 . Each gate  31  is pivotally movable between a closed position and an open position. When in the closed position, the gate  31  forms part of the wall  30 . When in the open position, the gate  31  may extend between opposite parts of the wall  30  or the enclosure  20 . That is, the gate  31  covers the pathway  40  that is formed by the gate  31 . 
         [0046]    The wall  30  also includes two arcuate returns  32 . The arcuate returns  32  are formed within the wall  30  which is stepped outwardly. Accordingly, the returns  32  are stepped outwardly from the pathway  40 . 
         [0047]    A funnel  50  connected to a pipe  51  is located adjacent the centre of the enclosure  20  adjacent the termination of the inward winding of the spiral wall  30 . The funnel  50  is used to transport fish out of the corral  10 . 
         [0048]    In use, fish are driven through the entrance  24 . The fish then follow the pathway  40  until they are removed through the funnel  50 . The gates  31  which form part of the wall  30  can be opened or closed depending on the required density of the fish. The gates  31  are typically used to increase the density of fish within a particular section of the corral  10  by closing the gates  31  to progressively reduce the length of pathway  40  that is accessible to the fish. The gates  31  can also be used to create a loop effectively placing the fish in a holding position if required. It should be appreciated that the height of the corral  10  within the water can also be increased or decreased to increase or decrease the density of the fish. 
         [0049]    The returns  32  function such that fish swimming along the pathway  40  in the opposite direction to that intended are redirected in the correct direction. That is, the fish are turned around. As the returns  32  are stepped outwardly from the pathway  40 , fish swimming in the opposite direction to that intended are “redirected” in the correct direction while fish swimming in the correct direction are unimpeded. 
         [0050]      FIGS. 3 to 5  show an fish accumulator  110  that is used to distribute fish after they have been caught but before they have been slaughtered. The fish accumulator  110  includes a tank  120 , an entrance  130 , an exit  140  and a rotation device  150 . 
         [0051]    The tank  120  is used to house fish. The tank  120  is a cylindrical in shape and is formed from two ends  121  and  122  interconnected by a curved tank sidewall  123 . A viewing window  124  is located within a top tank end  121 . A cone  125  is located on a bottom tank end  122  of the tank to assist with water flow within the tank  120 . 
         [0052]    The entrance  130  is used to pass fish into the tank  120 . The entrance is fluidly connected to the funnel  50  which used to transport fish from the corral  10 . The entrance  130  is located through the tank side wall  123 . The entrance  130  is orientated substantially tangentially with respect to the tank side wall  123 . 
         [0053]    A fish guide  160  is located within the tank  120  with the start of the fish guide  160  being located adjacent to the entrance  130 . The fish guide  160  is in the form of a helical platform which spirals downwardly. Accordingly, when a fish passes through the entrance  130 , the fish and water is directed to travel in a clockwise direction within the tank  120 . Further, the fish is directed away from the entrance  130  so not as to block the entrance of any other fish. 
         [0054]    The exit  140  is used to remove fish from the tank  120 . The exit is located adjacent the bottom tank end  122 . The exit  140  is orientated substantially tangentially with respect to the tank side wall in a similar manner to the entrance  130 . It should be appreciated that the exit  140  and the entrance  130  do not have to be in alignment. However, exit and the entrance are orientated in a similar tangential manner. 
         [0055]    A first rotation device, in the form of a water rotation inlet  150 , is mounted within the tank side wall to rotate the water in the same direction (clockwise) as the flow created by the entry  130 . Accordingly the water rotation inlet is orientated substantially tangentially with respect to the tank side wall  123 . The water inlet is oriented in the same direction to that of the entrance  130  and the exit  140 . 
         [0056]    A vacuum/pressure inlet  170  is fluidly connected to tank  120 . The vacuum/pressure inlet  170  is used to pass water into and out of the tank  120  using an associated pump (not shown). The vacuum/pressure inlet  170  is orientated longitudinally with respect to the tank  120  so that the passing of water into and out of the tank  120  does not contribute substantially to the flow of the water within the tank  120 . 
         [0057]    An entrance valve (not shown) and an exit valve (not shown) is used in conjunction with the vacuum/pressure inlet  170  when passing water into and out of the tank  120  via the vacuum/pressure inlet  170 . 
         [0058]    In use, the tank  120  is substantially full of water. The water rotation inlet  150  is operated as necessary to help maintain the water rotation when the tank is emptied and as necessary at other times to maintain the rotation velocity. 
         [0059]    When fish are to be transported into the tank  120  from the corral  10 , the exit valve is closed and the entrance valve is opened. A vacuum is then drawn through vacuum pressure inlet  170 . Water and fish is then sucked through the vacuum/pressure inlet  130 . This causes water and fish to be drawn from within the corral  10 . Water and fish then pass through the entrance  130  and are directed along the fish guide  160  into the tank  120 . The fish guide  160  enables a gentle entry of the fish into the tank  120  (as opposed to a sudden drop). 
         [0060]    Once the fish are located within the tank  120 , the fish will naturally swim against the current. When fish enter the tank tail first they are already in the current orientation relative to the exit. Fish entering head first are expected to change direction to swim in to the water current in the tank  120 . Accordingly, if the current (created by movement of the water) is flowing in a clockwise direction, then the fish will swim in an anti-clockwise direction. It should be appreciated that the exit valve and the entrance valve can be closed with no water passing through the vacuum/pressure inlet to hold the fish within the tank  120 . 
         [0061]    In order to transport fish out of the tank  120 , the exit valve is opened and the entrance valve is closed. Air is then pumped through the vacuum/pressure inlet  170  to transport the fish through the exit  140 . It should be appreciated that as the fish are facing in an anti-clockwise direction, their head is facing toward the exit  140 . Accordingly, it is envisaged that the majority of fish will pass head first through the exit  140 . It is therefore also envisaged that the damage a fish can sustain, by passing through the exit tail first, is reduced or eliminated. 
         [0062]    In an alternative embodiment of the invention water and fish may be pumped on a continuous basis through the tank, using the same entry and exit points but without the need for valves on the inlet or outlet. 
         [0063]    In this specification, the terms “comprise”, “comprises”, “comprising” or similar terms are intended to mean a non-exclusive inclusion, such that a system, method or apparatus that comprises a list of elements does not include those elements solely, but may well include other elements not listed. 
         [0064]    It will also be appreciated that various other changes and modifications may be made to the invention described without departing from the spirit and scope of the invention.