Patent Publication Number: US-2021176971-A1

Title: Involuntary guidance and transport system for fish

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is based on and claims the benefit of U.S. provisional patent application Ser. No. 62/948,501, filed Dec. 16, 2019, the content of which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     Many species of fish exhibit seasonal migrations when large numbers of individuals migrate through streams and rivers. In many cases, these migrating fish are attempting to access their breeding grounds. In the case of native fish, management efforts often aim to facilitate these migrations, especially if migration routes are blocked by dams or other physical barriers. In the case of invasive fish, the goal is to block these migrations and remove the fish. 
     The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all disadvantages noted in the background. 
     SUMMARY 
     A system includes a fish stunner configured to stun fish within a stunning zone of a waterway and a conveyor with a portion of the conveyor located below a waterline of the waterway and a second portion of the conveyor located above the waterline such that fish that have been stunned reach the conveyor and are lifted out of the water by the conveyor. In accordance with a further embodiment, a method includes activating a fish stunner in a waterway to produce stunned and drifting fish and directing the stunned and drifting fish onto a conveyor that is at least partially in the waterway. The conveyor is then used to lift stunned fish out of the waterway. 
     In accordance with a still further embodiment, a system includes a fish holding area and a stunning device located in a waterway and a conveyor located relative to the stunning device such that stunned fish move with a current onto the conveyor. 
     In accordance with a still further embodiment, a fence for a waterway includes first and second lateral supports, each having a plurality of holes, and a plurality of posts. Each post passes through a respective hole of the plurality of holes of the first lateral support and a respective hole of the plurality of holes of the second lateral support such that each post moves through the post&#39;s respective holes independently of other posts of the plurality of posts. 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view of an involuntary guidance and transport system for fish in accordance with one embodiment. 
         FIG. 2  is a side view of a portion of the system of  FIG. 1 . 
         FIG. 3  is a plan view of an involuntary guidance and transport system for fish in accordance with a second embodiment. 
         FIG. 4  is a plan view of an involuntary guidance and transport system for fish in accordance with a third embodiment. 
         FIG. 5  is a plan view of an involuntary guidance and transport system for fish in accordance with a fourth embodiment. 
         FIG. 6  is a side view of two sections of a fence in accordance with one embodiment. 
         FIG. 7  is a top view of the two sections of fence of  FIG. 6 . 
         FIG. 8  is a top view of the two sections of fence of  FIG. 6  in a different orientation relative to each other. 
         FIG. 9  is a flow diagram of a method of constructing an involuntary guidance and transport system for fish in accordance with one embodiment. 
         FIG. 10  is a flow diagram of a method of using an involuntary guidance and transport system for fish in accordance with one embodiment. 
     
    
    
     DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
     Embodiments described below provide an efficient means for removing migrating fish from a waterway without killing the fish. 
       FIG. 1  provides a system  100  for removing migrating fish from a waterway  102 , such as a river or stream. Waterway  102  is defined between two riverbanks  104  and  106  through which a water current flows in a direction  108 . During migration, different species of fish will migrate along waterway  102  by swimming against the direction of water flow  108  from a downstream position  110  toward an upstream position  112 . 
     System  100  includes a barrier  114  positioned in river  102  along a direction  109  at an angle θ relative to the flow direction  108  of waterway  102  where θ is generally greater than 90° and less than 180°. Migrating fish generally swim against flow direction  108 . When a migrating fish reaches barrier  114 , the fish is unable to swim through barrier  114  and as a result, the fish&#39;s efforts to continue moving upstream against flow direction  108  cause the fish to move upstream along barrier  114  as shown generally by fish paths  130 ,  132  and  134 . 
     In accordance with some embodiments, barrier  114  is a physical fence made for example from poly-vinyl chloride (PVC) posts or stakes that are connected together by lateral supports to provide a space between each post that allows water to flow through the posts but prevents migrating fish from passing between the posts. In other embodiments, barrier  114  is an electrical barrier or a guidance/deterrence system consisting of one or more suspended electrodes along the barrier. In other embodiments, barrier  114  could be an electric barrier placed on the bottom of the stream. In other embodiments, barrier  114  is an acoustic or light guidance/deterrence system. In  FIG. 1 , the barrier consists of two parallel chains of electrodes  150  and  152  that develop an electric field between the chains such that the electric field increases in intensity closer to chain  150 . 
     Barrier  114  leads the migrating fish to a gate  120  in a fence  118  that defines a holding area  116 . Fence  118  includes a holding portion  140  that defines an upstream portion of holding area  116 . After migrating fish pass through gate  120 , they continue to swim upstream until they are stopped by holding portion  140  of fence  118 . The fish continue to swim against the current at this position and thus remain in the upstream portion of holding area  116 . In accordance with one embodiment, fence  118  is a physical barrier constructed of spaced-apart posts that extend from the bottom of the waterway to above the waterline. The spaced-apart posts are connected together by lateral supports so that there is enough space between the posts to allow the water current to pass through fence  118  while preventing the migrating fish from passing through fence  118 . In accordance with some embodiments, fence  118  is made of PVC. 
     Holding area  116  includes a crowding device  122 , a fish stunning device  124 , and a conveyor  126 . Fish stunning device  124  is located downstream of crowding device  122  and at least a portion of conveyor  126  is located relative to stunning device  124  such that stunned fish are carried by a current to conveyor  126 . In system  100 , crowding device  122  consists of rows of electrodes, such as rows  160 ,  162 ,  164 ,  166 ,  168  and  170 . The rows of electrodes are capable of being independently energized to generate an electric field between the electrodes in a row-by-row fashion. By sequentially energizing the rows of electrodes starting from the furthest upstream row  160  and ending with the furthest downstream row  170 , it is possible to direct the fish downstream thereby crowding the fish around the stunning device  124 . Specifically, when a row of electrodes is activated, fish that are within the electric field generated by the electrodes will be irritated by the electric field and will swim downstream until they are outside of the electric field. This will place the fish in the area around the next row of electrodes, which are then activated thereby causing the fish to swim further downstream. When a row of electrodes is activated, it may remain activated so that eventually all of the rows of electrodes are energized at the same time or the row may be deactivated a short time after the row downstream from the row is energized so that only one or two rows of electrodes are energized at the same time. 
     To prevent the fish from exiting holding area  116  during this crowding, gate  120  is closed before crowding device  122  is activated. In accordance with one embodiment, gate  120  consists of two electrodes  172  and  174  that are energized to close gate  120  and are de-energized to open gate  120 . In other embodiments, gate  120  can be a physical movable gate that can move vertically out of the waterway, pivot laterally on a hinge, or slide laterally within the waterway, for example. 
     Stunning device  124 , also referred to as fish stunner  124 , consists of two or more electrodes such as electrodes  180  and  182  that are de-energized until fish have been crowded around stunning device  124  by crowding device  122  and then are energized to generate an electric field that stuns fish in a stunning zone  184 . Although fixed electrodes are shown in the Figures, stunning device  124  can also be implemented using portable electrodes such as a backpack electrofisher or a floating vessel (e.g. boat) with electrodes. In accordance with one embodiment, stunning zone  184  is a volume of water that extends from the top surface of the water to the bottom of the waterway and that extends both upstream and downstream of electrodes  180  and  182 . In accordance with one embodiment, at least a portion of conveyor  126  is located relative to the stunning zone  184  such that stunned fish will drift with a current from stunning zone  184  to conveyor  126 . In accordance with one embodiment, electrodes  180  and  182  only need to be momentarily energized in order to stun the fish and once the fish are stunned, the electrodes  180  and  182  are turned off. Once stunned, the fish are temporarily unable to swim but are still alive. Because they are unable to swim, the stunned fish drift with the current, which can be the natural current of waterway  102  or an artificial current generated by one or more pumps. 
     A stunned fish cannot be controlled using electrodes because the fish is unable to swim away from an electric field. In order to ensure that each stunned fish comes into contact with conveyor  126 , a set of physical guides are placed in the waterway that extend from the sides and bottom of conveyor  126  in an upstream direction past stunning device  124 . Such physical guides physically restrain where the fish can drift to as opposed to electric field guides that use electric fields to guide the fish. In some embodiments, the physical guides extending from the sides of conveyor  126  are constructed of spaced-apart posts that extend from the bottom of the waterway to above the waterline and the guide at the bottom of the conveyor is a board or a metal surface. The spaced-apart posts are connected together by lateral supports that maintain the spacing between the posts to allow the water current to flow through the physical guides while preventing fish larger than a threshold size from passing through the guides. The spacing between the posts is selected to prevent the targeted migrating fish from passing through the guides after the fish have been stunned while allowing smaller fish to pass through the guides. In the embodiment of  FIG. 1 , the physical guides are formed from conveyor guide portions  142  and  144  of fence  118 , which extend upstream from sides  190  and  192  of conveyor  126  to a position that is upstream from electrodes  180  and  182 . 
       FIG. 2  provides a side view of a portion of system  100  showing conveyor  126 , stunning electrode  182  and conveyor guide portion  142  and a bottom guide  198 . Conveyor  126  is supported on a bottom  202  of the waterway by supports  204  and  206  which support a frame  212  of conveyor  126 . Frame  212  in turn supports a belt  210  and an electric motor  216 . Frame  212  and belt  210  are at an angle to a top surface  200  of waterway  102  such that an upstream portion  252  of frame  212  and belt  210  is below the waterline marked by top surface  200  and a downstream portion  250  of frame  212  and belt  210  is above the waterline marked by top surface  200 . In accordance with the embodiment of  FIG. 2 , upstream portion  252  of frame  212  and belt  210  are positioned near a bottom  202  of waterway  102 . Bottom guide  198  is a board  290  supported by legs  292  or frame  212 , which in turn are supported by support  204 . 
     Motor  216  is rotatably engaged with belt  210  such that when motor  216  is on and rotating, motor  216  rotates belt  210  around frame  212  in a direction  214 . Belt  210  includes a plurality of supports, such as supports  218  and  220 , which extend away from the surface of belt  210  so as to provide a surface for supporting fish as they are conveyed from waterway  102  to a top end  234  of conveyor  126 . Belt  210  has a width  194  that extends from side  190  to side  192  between guide portions  142  and  144  such that any gap between belt  210  and guide portions  142  and  144  is small enough to prevent a stunned fish from passing through the gap. As shown in  FIG. 2 , guide portions  142  and  144  extend from top end  234  of conveyor  126  to a position upstream of stunning electrode  182 . In accordance with one embodiment, guide portions  142  and  144  extend to an upstream end of stunning zone  184  to ensure that all stunned fish drift onto conveyor  126  due to the flow of water in direction  108 . Bottom guide  198  has a downstream end that is above the upstream end of conveyor  126  and an upstream end that rests on bottom  202  of the waterway. Bottom guide  198  prevents fish from swimming or drifting below conveyor  126 . 
     As belt  210  rotates around conveyor  126 , drifting stunned fish in waterway  102  contact belt  210  and the supports of belt  210 , such as supports  218  and  220 , and are transported along conveyor  126  by belt  210  to end  234  of conveyor  126 . When the fish reach end  234 , they drop from end  234  onto a lateral conveyor or slide  240 , which conveys the stunned fish to a receptacle or transport vehicle  242  located on the riverbank. The stunned fish can then be transported to another part of the waterway or can be sorted to remove invasive species before returning non-invasive species to the water. 
     In  FIG. 1 , the width  196  of upstream portion  140  of holding area  116  is shown to be substantially the same as width  194  of conveyor  126 .  FIG. 3  provides an alternative embodiment in which the width  300  of holding area  116  is wider than width  194  of conveyor  126 . To achieve this, the fence  318  that defines holding area  116  in  FIG. 3  includes guide portions  342  and  344  that extend from sides  190  and  192  of conveyor  126  to a position upstream from stunning devices  180  and  182  and include two angled portions  360  and  362  that narrow holding area  116  from width  300  to width  194 . In accordance with one embodiment, the angle of angled portions  360  and  360  to flow direction  108  is selected to ensure that drifting stunned fish will be guided to conveyor  126  and will not become trapped against angled portions  360  and  362 . 
       FIG. 4  provides an alternative embodiment showing a system  400 , which is identical to system  100  of  FIG. 1  except for including a different crowding device  422 . In  FIG. 4 , instead of using electrodes to form the crowding device, a crowding device  422  is provided that includes a movable fence  401  that moves along two guides  402  and  404 . As fence  401  is moved in a downstream direction  108 , fish in holding portion  140  are guided downstream toward stunning zone  184 . When movable fence  401  reaches a position  406 , stunning electrodes  180  and  182  are energized thereby stunning but not killing the fish, which then drift onto conveyor  126 . In  FIG. 4 , instead of using electrodes  172  and  174  for gate  120 , system  400  uses a physical gate  420 , which can either be in an opened position  423  to allow fish to enter holding area  116  or a closed position  424 , to prevent fish from exiting holding area  116  while moving movable fence  401  downstream. In accordance with a further alternative embodiment, crowding device  422  includes a floating platform instead of fence  401 . The floating platform has a row of electrodes attached to it and can be pulled downstream to guide fish in holding portion  140  toward stunning zone  184  and can be pulled upstream to provide a space in holding portion  140  for more fish. 
       FIG. 5  provides another system  500  for removing migrating fish from waterway  102  when the fish are migrating downstream in the direction of water flow  108 . 
     System  500  includes a barrier  514  positioned in river  102  at an angle θ relative to the flow direction  108  of waterway  102  where θ is generally less than  90 . When a migrating fish reaches barrier  514 , the fish is unable to swim through barrier  514  and as a result, the fish&#39;s efforts to continue moving downstream cause the fish to move downstream along barrier  514  as shown generally by fish paths  530 ,  532  and  534 . 
     In accordance with some embodiments, barrier  514  is a physical fence made for example from poly-vinyl chloride (PVC) posts or stakes that are connected together by lateral supports to provide a space between each post that allows water to flow through the posts but prevents migrating fish from passing between the posts. In other embodiments, barrier  514  is an electrical barrier or a guidance/deterrence system consisting of one or more suspended electrodes along the barrier. In other embodiments, barrier  514  could be an electric barrier placed on the bottom of the stream. In other embodiments, barrier  514  is an acoustic or light guidance/deterrence system. In  FIG. 5 , the barrier consists of two parallel chains of electrodes  550  and  552  that develop an electric field between the chains such that the electric field increases in intensity closer to chain  550 . 
     Barrier  514  leads the migrating fish to a gate  520  in a fence  518  that defines a holding area  516 . In accordance with one embodiment, fence  518  is a physical barrier constructed of spaced-apart posts that extend from the bottom of the waterway to above the waterline. The spaced-apart posts are connected together by lateral supports so that there is enough space between the posts to allow the water current to pass through fence  518  while preventing the migrating fish from passing through fence  518 . In accordance with some embodiments, fence  518  is made of PVC. 
     Holding area  516  includes a crowding device  522 , a fish stunning device  524 , and conveyor  526 . Fish stunning device  524  is located downstream of crowding device  522  and at least a portion of conveyor  526  is located downstream from fish stunning device  524 . In system  500 , crowding device  522  consists of rows of electrodes, such as rows  560 ,  562 ,  564 ,  566 ,  568  and  570 . The rows of electrodes are capable of being independently energized to generate an electric field between the electrodes in a row-by-row fashion. By sequentially energizing the rows of electrodes starting from the furthest upstream row  560  and ending with the furthest downstream row  570 , it is possible to direct the fish downstream thereby crowding the fish around stunning device  524 . Specifically, when a row of electrodes is activated, fish that are within the electric field generated by the electrodes will be irritated by the electric field and will swim downstream until they are outside of the electric field. This will place the fish in the area around the next row of electrodes, which are then activated thereby causing the fish to swim further downstream. When a row of electrodes is activated, it may remain activated so that eventually all of the rows of electrodes are energized at the same time or the row may be deactivated a short time after the row downstream from the row is energized so that only one or two rows of electrodes are energized at the same time. 
     To prevent the fish from exiting holding area  516  during this crowding, gate  520  is closed before crowding device  522  is activated. In accordance with one embodiment, gate  520  consists of two electrodes that are energized to close gate  520  and are de-energized to open gate  520 . In other embodiments, gate  520  can be a physical movable gate that can move vertically out of the waterway, pivot laterally on a hinge, or slide laterally within the waterway, for example. 
     Stunning device  524 , also referred to as fish stunner  524 , consists of at least two electrodes, such as electrodes  580  and  582 , that are de-energized until fish have been crowded around stunning device  524  by crowding device  522  and then are energized to generate an electric field that stuns fish in a stunning zone  584 . In accordance with one embodiment, stunning zone  584  is a volume of water that extends from the top surface of the water to the bottom of the waterway and that extends both upstream and downstream of the electrodes that form fish stunner  524 . In accordance with one embodiment, at least a portion of conveyor  526  is located downstream from stunning zone  584 . In accordance with one embodiment, the electrodes of fish stunner  524  only need to be momentarily energized in order to stun the fish and once the fish are stunned, the electrodes are turned off. Once stunned, the fish are temporarily unable to swim but are still alive. Because they are unable to swim, the stunned fish drift with the current of the waterway, which can be the natural current of the waterway or an artificially generated current formed by one or more pumps. 
     A stunned fish cannot be controlled using electrodes because the fish is unable to swim away from an electric field. In order to ensure that each stunned fish comes into contact with conveyor  526 , a set of physical guides are placed in the waterway that extend from the sides and bottom of conveyor  526  in an upstream direction past stunning device  524 . Such physical guides physically restrain where the fish can drift to as opposed to electric field guides that use electric fields to guide the fish. In some embodiments, the physical guides are constructed of spaced-apart posts that extend from the bottom of the waterway to above the waterline. The spaced-apart posts are connected together by lateral supports that maintain the spacing between the posts to allow the water current to flow through the physical guides while preventing fish larger than a threshold size from passing through the guides. The spacing between the posts is selected to prevent the targeted migrating fish from passing through the guides after the fish have been stunned while allowing smaller fish to pass through the guides. 
     Conveyor  526  has the same structure and operates in the same manner as conveyor  126 . After fish stunner  524  has been activated, a motor on conveyor  526  is turned on causing a belt to rotate around conveyor  526 . Drifting stunned fish in waterway  102  contact the belt and supports of the belt and are transported along conveyor  526  to an end of conveyor  526 . When the fish reach the end of conveyor  526 , they drop from the end onto a lateral conveyor or slide  540 , which conveys the stunned fish to a receptacle or transport vehicle  542  located on the riverbank. The stunned fish can then be transported to another part of the waterway or can be sorted to remove invasive species before returning non-invasive species to the water. 
       FIG. 6  provides a side view and  FIG. 7  provides a top view of two sections  600  and  602  of fence  118  that can also be used as physical guides. Section  600  consists of lateral supports  604  and  606  and hollow posts  608 ,  610 ,  612 ,  614 ,  616 .  618 ,  620 ,  622 ,  624 ,  626 ,  628  and  630 , which pass through respective holes in lateral supports  604  and  606 . Section  602  consists of lateral supports  634  and  636  and hollow posts  630 ,  640 ,  642 ,  644 ,  646 ,  648 ,  650 ,  652 ,  654 ,  656 ,  658 , and  660 , which pass through respective holes in lateral supports  634  and  636 . Note that hollow post  630  is part of both section  600  and section  602  and passes through respective holes in lateral supports  604 ,  606 ,  634  and  636 . 
     During installation, sections of the fence are first formed by inserting hollow posts in each of the holes of the two lateral supports of the section with the exception of the holes at the ends of the lateral supports. In accordance with one embodiment, the holes of the lateral supports are sized relative to the hollow posts such that the hollow posts are held in place in the lateral supports by friction. A section of the fence is then taken to its desired position in the waterway and two or more of the hollow posts in the section are driven into the bottom  202  of the waterway so that they become embedded in the waterway as indicated by the dotted lines of  FIG. 6 . This temporarily secures the section in the waterway. The next section in the fence is then placed in a desired position in the waterway. This position is such that the holes at the ends of the lateral supports of the two sections overlap. A hollow post is then inserted through the four lateral supports to connect the two sections together. Two or more of the hollow posts of the new section are then driven into bottom  202  of the waterway. This section-by-section construction continues until the fence is complete. Any hollow posts that have yet to be driven into bottom  202  are then driven into bottom  202  to firmly secure fence  118  to bottom  202 . 
     Because of the spacing between the hollow posts, water can flow between the posts while the sections are being moved into position. This makes it easier to move the sections than if the sections were made of solid walls. In addition, because the hollow posts can be independently driven into bottom  202 , each post can be driven a different amount so as to accommodate unevenness in bottom  202 . In addition, because the hollow posts can be independently driven into bottom  202 , if scouring occurs underneath any of the posts, these posts can be driven further into the sediment without the need to readjust the entire panel, which would be the case of posts were attached to lateral supports by means other than friction. This makes installation and maintenance much more practical than if the posts were attached to lateral supports by means other than friction. 
     As shown in the top view of  FIG. 8 , sections  600  and  602  can be placed at any desired angle, Φ, relative to each other by pivoting the sections around hollow post  630 . 
       FIG. 9  provides a method of constructing a fish collection system in accordance with one embodiment. In step  900 , a barrier is constructed in a moving waterway to lead fish to a gate. At step  902 , a holding area is created in the waterway on the other side of the gate. At step  904 , physical guides are placed at the downstream portion of the holding area and at step  906 , a conveyor is placed within the physical guide so an upstream portion of the conveyor is submerged to the bottom of the waterway and a downstream portion of the conveyor is out of the water. At step  908 , fish stunners are placed just downstream of the upstream opening of the physical guide and at  910 , a crowding device is placed in the holding area upstream from the fish stunners. Although the steps of  FIG. 9  are shown in one order, those skilled in the art will recognize that the steps may be performed in any desired order. 
       FIG. 10  provides a flow diagram of a method of collecting fish. In step  1000  of  FIG. 10 , a barrier is used to drive fish into a holding area through a gate. At step  1002 , the gate is closed and at step  1004 , a crowding device is used to drive fish within the holding area toward one or more stunning devices. At step  1006 , the stunning devices are activated. At step  1008 , the stunned fish are allowed to drift with the current of the waterway using physical guides to ensure the stunned fish contact a conveyor. At step  1010 , the conveyor is activated to lift the drifting and stunned fish from the water as the water current brings the fish into contact with the conveyor and to place the fish on a lateral conveyance to a riverbank. In accordance with one embodiment, the belt is stationary while the crowding device is activated and immediately before the stunning device is activated to prevent actively swimming fish from being lifted by the conveyor. This helps to prevent fish from jumping off the conveyor and back into the waterway. 
     Although elements have been shown or described as separate embodiments above, portions of each embodiment may be combined with all or part of other embodiments described above. 
     Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms for implementing the claims.