Patent Publication Number: US-2021185992-A1

Title: Apparatus for sorting marine species in fish trawl

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation-in-part of, and claims the benefit of priority from, U.S. patent application Ser. No. 16/007,640 filed on Jun. 13, 2018, entitled “Apparatus for Sorting Marine Species in Fish Trawl,” which claims the benefit of priority from U.S. Provisional Patent Application Ser. No. 62/518,658, filed on Jun. 13, 2017, the contents of which are incorporated herein by reference. 
    
    
     STATEMENT REGARDING FEDERAL RIGHTS 
     The invention described herein was made with support from the National Oceanic and Atmospheric Administration (NOAA) of the United States Department of Commerce. The United States Government has certain rights in the invention. 
    
    
     FIELD OF THE INVENTION 
     The present disclosure relates generally to a fishing trawl device for selectively excluding undesired marine species from target species while harvesting. 
     BACKGROUND OF THE INVENTION 
     A function of a fish or shrimp trawl is to filter the sea life and benthic organisms from the water but, by design, a trawl can be indiscriminate. Environmental concerns have driven efforts to protect many marine species in a trawl&#39;s pathway. Many trawl fisheries have been incorporating devices such as sorting grids to exclude bycatch (protected or unmarketable composition of the catch) such as sea turtles, sharks, rays, seals, sturgeon, marine mammals, etc. The diminished weight and labor involved in handling the unwanted bycatch reduces fuel consumption, minimizes wear and tear on the gear, and lowers the cost of labor. Typically, a rigid sorting grid is sewn inside of a trawl where the catch is collected and enables removal of bycatch without any significant loss of the target species. 
     An example of a rigid sorting grid incorporated into a trawl is the Turtle Excluder Device (TED), which allows a protected sea turtle caught in shrimp trawl equipped with a TED to escape. TED grids physically direct bycatch larger than the bar spacing towards an opening in the webbing. Large sharks and sea turtles are separated and removed from the catch as the shrimp are collected in the cod end. 
     Rigid metal sorting grids are effective in shrimp trawls, but transferring that technology to a fish trawl is challenging. Fish trawls are often longer and heavier than shrimp trawls, which lead to the application of net reels to retrieve and deploy fish trawls. Winding a trawl onto a net reel creates torsion in the cables and webbing that can crush rigid grids when they are placed under each successive wrap of webbing and lines. Large scale fish trawls are made to be strong and pliable. Under extreme commercial fishing conditions, heavy loads and unpredictable sea conditions constantly test the integrity of the gear. A trawl built to hold 10,000 lbs. of catch should be expected to endure a magnitude of that weight when the catch is pulled through the water at high speeds, bounced across the sea floor, winched in by a boat in pitching seas (especially when the gear is at the surface), and finally lifted and discharged on deck. It is most likely the gear will begin to fail and fall apart at the point where an unyielding inflexible structure such as a rigid grid is sewn into the webbing of the trawl. Webbing distributes the stress of a heavy load over many knots and bars making meshes that can flex open and closed, absorbing stress and shock. When webbing is seized to a rigid frame this property is limited or lost and the ability of the trawl to withstand challenging conditions is compromised. A rigid structure sewn into a trawl will cause additional stress to the webbing under a heavy load and will diminish the overall loading capacity of the trawl. 
     A rigid grid is limited in how it can bend around a net reel and could break when the net reel applies excessive stress to the rigid grid. Another disadvantage of a rigid flat grid device in a fish trawl is the manner in which it filters the catch. The grid is sewn at an angle in the extension at the tail of the trawl, and is pitched towards an opening that allows turtles to escape from the trawl. A slow steady stream of fish has time to filter between the bars of the grid, but the trawl efficiency decreases when the rigid grid encounters a high volume of fish all at once. The webbing in front of the grid, especially around the opening, is unrestricted. When a large volume of fish is packed into the trawl the grid acts as a bottle neck that chokes down the webbing right behind the opening. As the limited amount of catch passes through the grid, or when the grid is overwhelmed and clogged, the mass in front of the grid quickly increases and expands in the webbing in front of the grid. The opening at the posterior end of the grid acts as a pressure relief for the built-up volume of fish packed ahead of the grid. When this occurs, a limited amount of fish will have time to pass through to the cod end of trawl net before the rest are discharged out of the opening. 
     Accordingly, there is a need for a trawl sorting grid device that provides a pliable grid when the net is pulled from the water and wound tightly on the net reel, and when the trawl is deployed in the water, the device is fixed into place inside the trawl and holds its shape with consistent grid spacing. There is also a need for a trawl sorting grid device that is strong enough to endure the repetitive, high volume and heavy loads of a commercial application while withstanding the punishing weather and sea conditions. 
     SUMMARY OF THE INVENTION 
     Embodiments of the present invention relate to methods and apparatus for sorting undesired marine species during trawling that provides a pliable grid when the trawl net is pulled from the water and wound tightly on the net reel, and when the trawl is deployed in the water, the apparatus is fixed into place inside the trawl and holding its shape with consistent grid spacing. 
     Accordingly, embodiments of the present invention relate to an apparatus for excluding undesired marine species from a trawl net during trawling, including a plurality of bars arranged in a symmetrical layout extending along a direction substantially traversing longitudinal axis of the trawl net, wherein the plurality of bars are separated by at least one predetermined bar spacing, wherein each of the plurality of bars has a predetermined length, wherein the plurality of bars have a predetermined stiffness; a grid frame surrounding the plurality of bars to form an opening at posterior end of the apparatus, wherein distal ends of at least two of the plurality of bars positioned distally from at least one of the plurality of bars positioned at the center of the grid frame is secured to the grid frame, wherein the opening formed at the posterior end of the apparatus allows for the undesired marine species to exit the trawl net; a plurality of back straps secured to at least one of the plurality of bars at a predetermined location, wherein each of the plurality of back straps is positioned perpendicular to the plurality of bars, wherein the plurality of back straps are positioned below the grid frame, wherein the plurality of back straps are separated by at least one predetermined distance; a grid frame extension secured to the grid frame to extend the posterior end of the apparatus above the opening, wherein the grid frame extension forms a curvature to receive flap netting positioned to seal the opening, wherein distal ends of the plurality of bars positioned proximally at center of the apparatus is secured to the grid frame extension, wherein the center bar is secured to the grid frame extension at apex of the curvature formed by the grid frame extension; a lead ring secured to ends of each of the plurality of back straps and proximal end of at least one of the plurality of bars, wherein the lead ring offsets the plurality of back straps and hold the plurality of bars at a predetermined angle, wherein the lead ring funnels marine species entering the trawl towards the plurality of bars; and a plurality of terminal couplers for securing the ends of each of the plurality of back straps and the proximal end of at least one of the plurality of bars to the lead ring, wherein the plurality of terminal couplers are oriented in a direction substantially facing the posterior end of the apparatus, wherein said apparatus is adapted for insertion within the trawl body before cod end of the trawl net, wherein lead ring is secured to fishing circle in the trawl net along a row of meshes perpendicular to the longitudinal axis of the trawl net, and wherein the back straps are secured to extension webbing in the trawl net. More particularly, each of the plurality of bars is a 1×19 stainless steel cable, and wherein each of the plurality of back straps is a 6×19 stainless steel cable. In one embodiment of the present invention, the plurality of back straps is secured to at least one of the plurality of bars with tuck splicing. 
     In some embodiments of the present invention, the lead ring is secured to proximal end of at least one of the plurality of bars. More particularly, the lead ring is a round hoop or a semi-circular hoop. In other embodiments of the present invention, the lead ring further includes a first lead ring secured to first ends of the plurality of back straps; and a second lead ring secured to second ends of the plurality of back straps, wherein the lead ring is open at top and bottom of the apparatus. More particularly, the proximal end of the plurality of bars are secured to at least one of the plurality of back straps secured to the first and second lead rings. 
     In one aspect of the present invention, the bar spacing separating the plurality of bars positioned proximal to the center of the grid frame is narrower than the bar spacing separating the plurality of bars positioned distally from the center of the grid frame. 
     In another aspect of the present invention, the at least one of the plurality of back straps positioned distally from the grid frame is shorter than the at least one of the plurality of back straps positioned proximal to the grid frame. 
     Some embodiments of the present invention further include a plurality of floats secured to predetermined locations on the plurality of bars, wherein the plurality of floats provide buoyancy to the apparatus. 
     In one embodiment of the present invention, the distance separating the ends of plurality of back straps is shorter than the distance separating the plurality of back straps proximal to the at least one of the plurality of bars positioned at the center of the grid frame. 
     Another embodiment of the present invention relates to an apparatus for excluding undesired marine species from a trawl net during trawling, including a grid comprising an array of plurality of bars and a plurality of back straps, wherein each of the plurality of bars is secured to at least one of the plurality of back straps at a predetermined location, wherein the plurality of bars are arranged vertically in a symmetrical layout on either side of a center bar, wherein the plurality of bars are spaced apart by at least one predetermined distance, wherein each of the plurality of bars has a predetermined length, wherein each of the plurality of back straps is positioned perpendicular to the plurality of bars; a grid frame surrounding the plurality of bars to form an opening at posterior end of the apparatus, wherein distal ends of at least two of the plurality of bars positioned distally from the center bar is secured to the grid frame, wherein the at least one of the plurality of back straps positioned distally from the grid frame is shorter than the at least one of the plurality of back straps positioned proximal to the grid frame, wherein the distance separating the ends of plurality of back straps is shorter than the distance separating the plurality of back straps proximal to the at least one of the plurality of bars positioned at the center of the grid frame, wherein the opening formed at the posterior end of the apparatus allows for the undesired marine species to exit the trawl net; a grid frame extension secured to the grid frame to extend the posterior end of the apparatus above the opening, wherein the grid frame extension forms a curvature to receive flap netting positioned to seal the opening, wherein distal ends of the plurality of bars positioned proximally at center of the apparatus is secured to the grid frame extension, wherein the center bar is secured to the grid frame extension at apex of the curvature formed by the grid frame extension; a lead ring for funneling marine species entering the trawl towards the plurality of bars, wherein ends of each of the plurality of back straps and proximal end of at least one of the plurality of bars are secured to the lead ring, wherein the lead ring offsets the plurality of back straps and hold the plurality of bars at a predetermined angle, wherein the lead ring is secured to fishing circle along a straight row of meshes perpendicular to a direction the trawl net is pulled; a plurality of terminal couplers for securing the ends of each of the plurality of back straps and the proximal end of at least one of the plurality of bars to the lead ring, wherein the plurality of terminal couplers are oriented in a direction substantially facing the posterior end of the apparatus; and a plurality of floats secured to predetermined locations on the plurality of bars, wherein the plurality of floats provide buoyancy to the apparatus, wherein said apparatus is adapted for insertion within the trawl body before cod end of the trawl net, wherein lead ring is secured to fishing circle in the trawl net along a row of meshes perpendicular to the longitudinal axis of the trawl net, and wherein the back straps are secured to extension panel in the trawl net. More particularly, each of the plurality of bars is a 1×19 stainless steel cable, and wherein each of the plurality of back straps is a 6×19 stainless steel cable. In one aspect of the present invention, the lead ring is a round hoop. 
     In one embodiment of the present invention, bar spacing separating the plurality of bars positioned proximal to the center of the grid frame is narrower than the bar spacing separating the plurality of bars positioned distally from the center of the grid frame. 
     Some embodiments of the present invention relate to an apparatus for excluding undesired marine species from a trawl net during trawling, including a grid comprising an array of plurality of bars and a plurality of back straps, wherein each of the plurality of bars is secured to at least one of the plurality of back straps at a predetermined location, wherein the plurality of bars are arranged vertically in a symmetrical layout on either side of a center bar, wherein the plurality of bars are spaced apart by at least a first predetermined distance, wherein each of the plurality of back straps is positioned perpendicular to the plurality of bars, wherein the plurality of back straps are spaced apart by at least a second predetermined distance; a grid frame secured to the plurality of bars and the plurality of backstraps, wherein the grid frame surrounds the plurality of bars and the plurality of backstraps to form a rectangular section, a first curvature at anterior end of the rectangular section and a second curvature at posterior end of the rectangular section, wherein the plurality of bars are secured to the first and second curvatures formed by the grid frame; a lead ring formed by a first curved section, a second curved section and a straight section, wherein first end of the first curved section and first end of the second curved section are secured to the straight section and the grid frame; a plurality of setbacks positioned between the first curved section of the lead ring and the grid frame to form a first side panel and between the second curved section and the grid frame to form a second side panel, wherein the first and second side panels formed by the plurality of setbacks support the lead ring to funnel the marine species entering the trawl towards the plurality of bars; and a plurality of terminal couplers for securing the ends of each of the plurality of setbacks with the ends of the plurality of back straps and the grid frame, wherein said apparatus is adapted for insertion within the trawl body before cod end of the trawl net, wherein the lead ring is secured to fishing circle in the trawl net along a row of meshes perpendicular to the longitudinal axis of the trawl net, and wherein the undesired marine species exit the trawl net through the opening formed at the posterior end of the apparatus. 
     More particularly, the lengths of the setbacks positioned between the lead ring and the grid frame decrease from the distal end of the lead ring to the proximal end of the lead ring such that a plane of lead ring is set at a predetermined angle with a plane of the grid frame, and wherein the setbacks are spaced apart by at least the second predetermined distance. In one embodiment of the present invention, the angle between the plane of the lead ring and the plane of the grid frame is about 30 degrees. In some embodiments, the setbacks positioned between a second end of the first curved section of the lead ring and the grid frame and between a second end of the second curved section of the lead ring and the grid frame are secured to the grid frame and at least one of the plurality of backstraps using a four-way knuckle. In one aspect of the present invention, the first ends of the first and second curved sections of the lead ring are secured to the straight section of the lead ring and the grid frame using a four-way knuckle. In another aspect of the present invention, the back strap positioned at a center of the grid frame comprises two cables combined to form a single back strap. 
     In one embodiment of the present invention, the spacing separating the plurality of bars is about 6 inches and the distance separating the ends of back straps is about 24 inches. In another embodiment of the present invention, the length of the plurality of back straps is about 40 inches. 
     In some embodiments of the present invention, the bars positioned proximal to the center bar is longer than the at least one of the bars positioned proximal to a side of the grid frame and the center bar is secured to the grid frame at apex of the first and second curvatures formed by the grid frame. 
     Some embodiments of the present invention further include floats secured to predetermined locations on the bars to provide buoyancy to the apparatus. 
     In some aspects of the present invention, the lead ring and the grid frame are positioned inside a grid frame extension webbing. 
     Other embodiments of the present invention further include a lead extension panel secured to the lead ring and the grid frame, wherein the lead extension panel extends the grid frame extension webbing outside the lead ring; and a transition piece webbing for transitioning a shape of the trawl net from a two-seam trawl net to a four-seam trawl net, wherein the transition piece webbing comprises two top side panels, two bottom panels, a bottom belly panel, and a top belly panel, wherein the side panels, the bottom panels, the bottom belly panel, and the top belly panel of the transition piece webbing are secured using eight gore lines. More particularly, the bottom belly directs the marine species towards the grid frame, and wherein the bottom belly extends inside the grid frame extension webbing to form a ramp and transitions into a flap. 
     Embodiments of the present invention also relate to an apparatus for excluding undesired marine species from a trawl net during trawling, including a first grid panel comprising a plurality of first bars arranged horizontally in a symmetrical layout on either side of a first center bar, wherein each of the plurality of first bars is secured to at least one of a plurality of first back straps at a predetermined location, wherein the plurality of first bars are spaced apart by at least one predetermined distance, wherein each of the plurality of first bars has a predetermined length, wherein each of the plurality of first back straps is positioned perpendicular to the plurality of first bars; a second grid panel comprising a plurality of second bars arranged horizontally in a symmetrical layout on either side of a second center bar, wherein each of the plurality of second bars is secured to at least one of a plurality of second back straps at a predetermined location, wherein the plurality of second bars are spaced apart by at least one predetermined distance, wherein each of the plurality of second bars has a predetermined length, wherein each of the plurality of second back straps is positioned perpendicular to the plurality of second bars; a center post connecting the first and second grid panels, wherein proximal ends of the plurality of first and second bars are secured to the center post; a rectangular lead ring connected to the ends of the center post, wherein the longitudinal axis of the lead ring is perpendicular to the center post; a plurality of setbacks positioned between the first and second grid panels and the lead ring to support the first and second grid panels in a V-shape; a plurality of terminal couplers for securing the ends of each of the plurality of the first and second back straps and the proximal ends of the plurality of the first and second bars to the center post, wherein the plurality of terminal couplers secure the plurality of setbacks to the first and second grid panels and the lead ring, wherein said apparatus is adapted for insertion within the trawl body before cod end of the trawl net, wherein lead ring is secured to fishing circle in the trawl net along a row of meshes perpendicular to the longitudinal axis of the trawl net, and wherein the back straps are secured to the top quarter of extension panel in the trawl net. More particularly, each of the plurality of setbacks is positioned at substantially same locations as the plurality of the first and second back straps. In one embodiment of the present invention, each of the plurality of back straps is a 6×19 stainless steel cable, and wherein each of the plurality of back straps is a 6×19 stainless steel cable. In another embodiment of the present invention, each of the first and second grid panels have a length of about 5 feet and a height of about 3 feet. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  illustrates a marine species sorting apparatus in accordance with an embodiment of the present invention. 
         FIG. 2  illustrates an exemplary layout representing half grid of marine species sorting apparatus in accordance with an embodiment of the present invention. 
         FIG. 3  illustrates exemplary terminal couplers used in embodiments of the present invention. 
         FIG. 4  illustrates a second embodiment of marine species sorting apparatus in accordance with an embodiment of the present invention. 
         FIG. 5  illustrates an exemplary layout representing half grid of marine species sorting apparatus in accordance with the second embodiment of the present invention. 
         FIG. 6  illustrates another embodiment of marine species sorting apparatus having an alternate layout of bars and back straps. 
         FIG. 7  illustrates an exemplary layout representing half grid of marine species sorting apparatus having alternate layout of bars and back straps. 
         FIG. 8  illustrates a third embodiment of marine species sorting apparatus in accordance with an embodiment of the present invention. 
         FIG. 9  illustrates an exemplary layout representing half grid of marine species sorting apparatus in accordance with the third embodiment of the present invention. 
         FIG. 10  illustrates an alternate embodiment of the present invention for sorting marine species having a flat horizontal shape. 
         FIG. 11  illustrates an exemplary layout representing half grid of marine species sorting apparatus having a flat horizontal shape. 
         FIG. 12  illustrates an exemplary distribution of floats secured to marine species sorting apparatus in accordance with embodiments of the present invention. 
         FIG. 13  illustrates an alternate embodiment of marine species sorting apparatus in accordance with an embodiment of the present invention. 
         FIG. 14  illustrates an exemplary layout representing a grid frame of an alternate embodiment of the marine species sorting apparatus. 
         FIG. 15  illustrates an exemplary layout representing a side panel of a grid frame of an alternate embodiment of the present invention. 
         FIG. 16  illustrates an exemplary layout representing a grid frame extension of an alternate embodiment of the present invention. 
         FIG. 17  illustrates an exemplary webbing panels for a transition piece webbing in an alternate embodiment of the present invention. 
         FIG. 18  illustrates an exemplary representing a bottom belly for an alternate embodiment of the marine species sorting apparatus. 
         FIG. 19  illustrates an exemplary half webbing panel for a bottom belly in an alternate embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts which can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention, and do not delimit the scope of the present invention. 
     Referring now to the drawings, and more particularly, to  FIG. 1 , there is shown an apparatus for sorting marine species during trawling, generally designated  100 , which comprises embodiments of the present invention. Marine species sorting apparatus  100  includes grid  102 , back straps  104 , and lead ring  106 . Grid  102  includes a plurality of bars  108  surrounded by grid frame  110 . Grid frame  110  surrounding bars  108  form an opening at posterior end of grid  102  to allow for the undesired marine species to exit the trawl net. Grid frame  110  is attached to lead ring  106  at an angle using terminal couplers  112 . Lead ring  106  supports grid  102  and secures marine species sorting apparatus  100  in trawl webbing referred to as the extension. 
     Grid  102  includes a plurality of bars  108 , each having a predetermined length and separated from each other by a predetermined bar spacing. Bars  108  are formed by cable or wire rope having a predetermined stiffness. In an embodiment of the present invention, bars  108  are made of 1×19 stainless steel cables. Each cable or wire rope include multi-wire strands arranged around a core. As used herein, the term “strand” refers to a grouping of wires wound together into individual cords that together make a wire rope. A wire rope is typically denoted by the number of strands, the number of wires in each strand and a description of its construction. For example, 1×19 cable denotes a wire rope that includes 1 strand made from 19 wires, and 6×19 IWRC denotes a wire rope including 6 strands having 19 wires per strand with 6 strands arranged around 1 Independent Wire Rope Core (IWRC). Typically, a 1×19 cable is stiffer than 6×19 IWRC, provided that they are both made of the same material with same overall diameter. 
     Bars  108  are arranged in a predetermined layout.  FIG. 2  illustrates an exemplary layout representing half grid for an embodiment of marine species sorting apparatus  100 . In one embodiment of the present invention, bars  108  are arranged in a symmetrical layout on either side of a center bar  108 - 0  extending along a direction substantially traversing longitudinal axis of the trawl net. In another embodiment of the present invention, bars  108  are arranged vertically in a symmetrical layout on either side of a center bar  108 - 0 , as shown in  FIGS. 1 and 2 . Bar  108 - 1  is positioned next to bar  108 - 0  and bar  108 - 12  is positioned farthest away from bar  108 - 0 , as shown in  FIG. 2 . In the embodiment shown in  FIGS. 1 and 2 , bar  108 - 0  is the longest bar and bar  108 - 12  is the shortest bar. The bottom end of each of bars  108 - 0  to  108 - 12  is connected to lead ring  106 . 
     Back straps  104  are cables positioned perpendicular to bars  108  to provide support to bars  108  and fix the spacing between bars  108 . Back straps  104  are typically softer and flexible cable than bars  108 . In an embodiment of the present invention, back straps  104  are made of the 6×19 cables. The difference in cables types determines the function of the cable grid. Stiffer cable helps maintain spacing between bars  108 , and more yielding cables in grid frame  110  and back straps  104  allow grid  102  to compact and reengage as marine species sorting apparatus  100  is crushed on a net reel and then deployed repeatedly. In the embodiment shown in  FIGS. 1 and 2 , back straps  104  are arranged horizontally with shortest back strap  104 - 1  at the bottom of grid  102  and the longest back strap  104 - 6  at the top of grid  102 . Back strap  104 - 6  is the longest backstrap and forms grid frame  110  around the opening at the posterior end of grid  102 . Back strap  104 - 6  is also referred to as the Opening Back Strap (OBS). Anchored to back strap  104 - 6  is a grid frame extension (GFE)  114 , which is also referred to as the last back strap and shown as back strap  104 - 7  in  FIG. 2 . Back straps  104  positioned in the middle or the upper portion of grid  102  influence the slope of bars  108 . In an exemplary embodiment of the present invention, back straps  104  positioned in the middle or the upper portion of grid  102  provide bars  108  with a slope having an angle of about 45 degrees. In another embodiment of the present invention, back straps  104  positioned in the middle or the upper portion of grid  102  provide bars  108  with a slope having a staggered pitch. By adjusting the length of back straps  104  between lead ring  106  and last bar  108 - 12 , grid  102  can have a steep angle at the bottom and a gradual slope at the top or vice versa. 
     Cable grid  102  is made with a series of bars  108  secured to back straps  104 . In one embodiment of the present invention, bars  108  are secured to back straps  104  using tuck splicing. Tuck splicing can be used to achieve a balance between flexibility and consistency in grid  102  by maintaining a consistent bar spacing and a fixed layout of grid  102 . While the splicing holds bars  108  tightly to back straps  104 , it allows for some movement when marine species sorting apparatus  100  is compressed for storage. When marine species sorting apparatus  100  is deployed and fishing, the splicing allows for bars  108  to form a well-defined grid. 
     Bars  108  are secured to back straps  104  at predetermined locations to maintain consistent bar spacing for a predetermined grid layout. In one embodiment of the present invention, bar spacing corresponds to the number of strands on each of back straps  104  between each of bars  108  and the corresponding tuck splice. In an exemplary layout shown in  FIG. 2 , the strand count for each of back straps  104  can be found between each of bars  108 . In  FIG. 2 , the number followed by the letter “s” on the layout denotes the number strands between each bar and the tuck splice, which corresponds to a bar spacing. For example, “3s” denotes 3 back strap strands between a bar and the tuck splice and corresponds to a bar spacing of about 3 inches. In a typical embodiment of the present invention, bar spacing at the central region of grid  102  is narrower than the bar spacing along the sides of grid  102 . Bar spacing along the sides of grid  102  is increased to compensate for the transition between the flat center of grid  102  to the curved sides of grid  102 . In one embodiment of the present invention, bar spacing at the central region of grid  102  is about 3 inches. The ends of bars  108  that are farthest from the opening at the posterior end of grid  102  are secured to lead ring  106  and the ends of bars  108  positioned at or closer to the opening at the posterior end of grid  102  are secured to GFE  114 . 
     Back straps  104  are positioned perpendicular to bars  108 , and parallel to each other with a predetermined space between each other and with a degree of offset. The length of back straps  104  are shortest when positioned away from the opening at the posterior end of grid  102  and longest when positioned at or closer to the opening at the posterior end of grid  102 . In the layout shown in  FIG. 2  for an exemplary embodiment in accordance with the present invention, the distance between the back straps is denoted on the layout. The distance between back straps  104  is determined by measuring and marking locations of the tucks on bars  108 . The distance and placement of the marks for tuck splicing can be found on the layout. Parallel back straps  104  with consistent distance between them are obtained when back straps  104  are spliced to the appropriate tuck marks on bars  108 . The distance between back straps  104  is shorter towards the lead ring and farthest apart at the center bar  108 - 0 . In some embodiments of the present invention, back straps  104  at the center of grid  102  are parallel, as shown in  FIGS. 4 and 5 . Back straps  104  fold around from the center to the sides of grid  102  to allow bars  108  located at the corners of grid  102  to shift and realign such that bar spacing at the corners and sides of grid  102  become comparable to the bar spacing at the center of grid  102  when grid  102  is submerged in ocean for fishing. 
     Flexibility of bars  108  can be limited by bar spacing. The spacing between back straps  104  can also be used to control bar spacing between two parallel bars having a predetermined degree of flex. Narrower spacing between back straps  104  can result in stiffer bars  108 . Using fewer back straps  104  in grid  102  can result in a lighter grid  102 . In an exemplary embodiment of the present invention, using a ½-inch cable for 1×19 bars and 9/16-inch cable for 6×19 back straps with 18 inches spacing between back straps and a bar spacing of about 3.5 inches can result in a grid capable of enduring more than 40 lbs. of force and spread the bars apart no more than ½-inch while the net is under tow. Stiffer cable bar material (such as 9/16 in. or larger diameter) allows for increased spacing between back straps  104 , or allows for the use of fewer back straps  104 . 
     Back straps  104  achieve a parabolic shape when marine species sorting apparatus  100  is submerged in ocean and deployed for fishing. The parabolic shape is achieved using setback in back straps  104 . Setback is the length of back straps  104  between lead ring  106  and the last bar  108 - 12 . Setbacks maintain the center of cable grid  102  at a predetermined angle. The shape of the parabola required for a predetermined setback of back straps  104  is set by varying the lengths of back straps  104 . Lengths of back straps  104  decreases from back strap  104 - 6  to back strap  104 - 1  such that back strap  104 - 6  forms the width of the parabola. Length of back strap  104 - 6  that forms the width of the parabola is further determined by the length of the opening at the posterior end of grid  102  in trawl net. The manner in which back strap  104 - 6  (OBS) and GFE  114  are secured to the webbing at the opening in trawl net will determine the width and shape of grid  102  at the opening. In one embodiment of the present invention, the dimensions of the opening are selected to maintain a shallow dip of at least three meshes below the first mesh of the forward cut in the bosom section to round the grid at the opening. Lengths of back straps  104  further influences the distance between lead ring  106  and the opening section of grid  102 . 
     In some embodiments of the present invention, back strap  104 - 6  (or the OBS) can be modified to form a grid frame extension  114  at the top of grid  102 , as further shown in  FIGS. 1 and 2 . Grid frame extension  114  increases the surface area of grid  102  while reaching up into a flap netting positioned over an opening at the posterior end of grid  102 , and sealing the flap netting to grid  102  by increasing the length of grid  102  exclusively at the bosom section of grid  102  at the opening. Grid frame extension  114  is formed by anchoring an additional back strap  104 - 7  to back strap  104 - 6 , as shown in  FIGS. 1 and 2 . Back strap  104 - 7  will be referred to as the Grid Frame Extension (GFE). Each of bars  108 - 0  through  108 - 6  is extended to connect with back strap  104 - 7  such that bar  108 - 0  is positioned at the apex of grid frame extension  114 . In one embodiment of the present invention, bar  108 - 0  is extended by about 12 inches longer than the original length. Each of bars  108 - 0  through  108 - 6  terminating at back strap  104 - 7  is connected to back strap  104 - 7  using a terminal coupler  112  and secured to back strap  104 - 6  using tuck splicing. In some embodiments of the present invention, the dimensions of terminal coupler  112  located at the center of grid frame extension  114  is selected to accommodate a cable including about three strands. Back strap  104 - 7  is capable of forming an arch having a greater degree of curvature than back strap  104 - 6 . Accordingly, the strand count on back strap  104 - 7  may differ from the strand counts on back strap  104 - 6 . Bars  108 - 0  through  108 - 6  are secured to back strap  104 - 6  and the ends of bars  108 - 0  through  108 - 7  are anchored to back strap  104 - 7 . The ends of back strap  104 - 7  are anchored to back strap  104 - 6  at predetermined locations. Table 1 provides exemplary dimensions for back straps  104 , bars  108 , lead ring  106 , bar spacings, and back strap spacings along center bar  108 - 0  for the exemplary embodiment (Type I) shown in  FIG. 2 . 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Type I Cable Grid 
               
               
                 (FIGS. 1-2) 
               
            
           
           
               
               
            
               
                 Cable Type 
                 Cable Length 
               
               
                   
               
               
                 Lead Ring 
                 18′10″ 
               
               
                 Bars 
                   
               
               
                 0 
                 10′ 
               
               
                 1 
                  9′11″ 
               
               
                 2 
                  9′9″ 
               
               
                 3 
                  9′7″ 
               
               
                 4 
                  9′4″ 
               
               
                 5 
                  9′1″ 
               
               
                 6 
                  8′9″ 
               
               
                 7 
                  8′5″ 
               
               
                 8 
                  7′5″ 
               
               
                 9 
                  7′1″ 
               
               
                 10 
                  6′8″ 
               
               
                 11 
                  6′3″ 
               
               
                 12 
                  5′8″ 
               
               
                 Backstraps 
                   
               
               
                 1 
                  4′6″ 
               
               
                 2 
                  6′8″ 
               
               
                 3 
                  9′ 
               
               
                 4 
                 12′ 
               
               
                 5 
                 16′ 
               
               
                 6 
                 25′3″ 
               
               
                 7 
                  6′6″ 
               
               
                   
               
               
                   
                 Distance 
               
               
                   
                 between 
               
               
                   
                 backstraps 
               
               
                 Backstraps 
                 at bar 0 
               
               
                   
               
               
                 0-1 
                 24″ 
               
               
                 1-2 
                 18″ 
               
               
                 2-3 
                 18″ 
               
               
                 3-4 
                 18″ 
               
               
                 4-5 
                 18″ 
               
               
                 5-6 
                 12″ 
               
               
                 6-7 
                 12″ 
               
               
                   
               
            
           
         
       
     
     The ends of each of back straps  104  and one end of each of bars  108  are anchored to lead ring  106  using terminal couplers  112 . In some embodiments of the present invention, the number of terminal couplers  112  needed for cable grid  102  can be determined by multiplying the total number of bars  108  and back straps  104  by two. In one embodiment of the present invention, each of terminal couplers  112  is a cylindrical pipe with one open end  112   a  for receiving each of back straps  104  and each of bars  108  and a half-ring link  112   b  welded to the second end of the pipe, as shown in  FIG. 3 . The diameter of open end  112   a  is selected to receive back straps  104  and bars  108 . The length of terminal couplers  112  can range from about 2 inches to about 6 inches. In one embodiment of the present invention, terminal couplers  112  can be made of ½-inch s-40 (304) Stainless steel. The diameter of half-ring link  112   b  can be about a one-quarter inch. The ends of each of back straps  104  and each of bars  108  are inserted into open end  112   a  of terminal couplers  112  and secured by crimping open end  112   a . Terminal couplers  112  can be linked or welded together to have multiple open ends for anchoring multiple back straps  104  and bars  108  to one location, or to form knuckles or corners, as further shown by exemplary embodiments of terminal couplers  112  in  FIG. 3 . In one embodiment of the present invention, terminal couplers  112  having two open ends are used to anchor one of back straps  104  and one of bars  108  to the same predetermined location on lead ring  106 . 
     Terminal couplers  112  anchored to lead ring  106  are oriented in the same direction and are positioned at predetermined locations on lead ring  106 . In one embodiment of the present invention, terminal couplers  112  are oriented in a direction substantially facing the posterior end of marine species sorting apparatus  100 . Terminal couplers  112  are anchored to lead ring  106  by locking half-ring link  112   b  on lead ring  106  at predetermined locations on lead ring  106 . In one embodiment of the present invention, each half-ring link  112   b  of terminal couplers  112  are locked into position on lead ring  106  by unwinding a pair of strands on lead ring  106  to the predetermined location on lead ring  106 , inserting the unwound pair of strands through the eye of half-ring link  112   b , sliding half-ring link  112   b  to the predetermined location, and winding the pair of strands to anchor half-ring link  112   b  to the predetermined location on lead ring  106 . In one embodiment of the present invention, spacing between terminal couplers  112  anchored to lead ring  106  correspond to the relative distance between back straps  104  on lead ring  106 . In another embodiment of the present invention, spacing between terminal couplers  112  anchored to lead ring  106  correspond to the relative bar spacing between each of bars  108  terminating at lead ring  106 , grid frame extension  114  or back strap  104 - 6 . Terminal couplers  112  can provide a pivoting joint while limiting the ability of each of back straps  104  and each of bars  108  to twist. A desired layout of grid  102  can be maintained with the combined ability of terminal couplers  112  to limit the twisting of each of bars  108  and the ability of each tuck splicing to maintain a consistent bar spacing. 
     Lead ring  106  is located along the bottom of grid  102  and forms a foundation for cable grid  102 . Lead ring  106  anchors back straps  104  into the fishing circle of a trawl and positions bars  108  of grid  102  away from the opening. Lead ring  106  serves as a vertical base to offset back straps  104  and hold bars  108  at an angle. The bottom end of bars  108  are secured to the bottom center section of lead ring  106  and back straps  104  are secured along either side of lead ring  106 . 
     In one embodiment of the present invention, lead ring  106  is formed by connecting the ends of a cable into a circle to form a round hoop, as shown in  FIG. 1 . Connections can be made by inserting each end of lead ring  106  into the open ends of a cylindrical pipe and crimping the pipe to secure the ends of lead ring  106  to the pipe. Lead ring  106 , as shown in  FIG. 1 , can be used to funnel large volume catches that push down the trawl bellies towards grid  102 . In embodiments of the present invention, as shown in  FIG. 1 , cable grid frame  110  is parabolic resulting in a grid that has more area for sorting fish than a flat rigid grid of same height and width. Embodiments of the present invention, as shown in  FIG. 1 , are suitable for use with high profile trawls (HPT). Exemplary high-profile trawls include a Flynet fish trawl, Midwater trawls, four seam box nets, fish trawls having circular cross section at the tail end of the bellies, and the like. 
       FIG. 4  illustrates a marine species sorting apparatus  400  in accordance with a second embodiment of the present invention, including a lead ring  406  that is a semi-circular hoop formed by securing each end of lead ring  406  to back strap  404 - 6  to open the top of lead ring  406 , as shown in  FIGS. 4 and 5 .  FIG. 5  illustrates an exemplary layout representing half grid of marine species sorting apparatus  400 . Lead ring  406  serves as a vertical base to offset back straps  404  and hold bars  408  at an angle. The bottom end of bars  408  are secured to the bottom center section of lead ring  406 .  FIG. 6  illustrates another embodiment of marine species sorting apparatus having an alternate arrangement of bars and backstraps, as shown in the exemplary layout of  FIG. 7 . Table 3 provides exemplary dimensions of back straps, bars, lead ring, bar spacings, and back strap spacings along the center bar for the exemplary embodiments (Type II-i and Type II-ii) shown in  FIGS. 5 and 7 . 
     
       
         
           
               
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Type II-i Cable Grid 
                 Type II-ii Cable Grid 
               
               
                 (FIGS. 4-5) 
                 (FIGS. 6-7) 
               
            
           
           
               
               
               
               
            
               
                 Cable Type 
                 Cable Length 
                 Cable Type 
                 Cable Length 
               
               
                   
               
               
                 Lead Ring 
                  13′2.5″ 
                 Lead Ring 
                 10′ 
               
               
                 Bottom 
                   3′10.5″ 
                   
                   
               
               
                 Sides 
                   4′8″ 
               
               
                   
               
               
                 Bars 
                   
                 Bars 
                   
               
               
                   
               
               
                 0 
                   8′ 
                 0 
                  7′6″ 
               
               
                 1 
                   7′9″ 
                 1 
                  3′9″ 
               
               
                 2 
                   7′ 
                 2 
                  7′3″ 
               
               
                 3 
                   5′ 
                 3 
                  3′6″ 
               
               
                   
                   
                 4 
                  6′5″ 
               
               
                   
                   
                 5 
                  2′11″ 
               
               
                   
                   
                 6 
                  4′10″ 
               
               
                   
                   
                 7 
                  3′10″ 
               
               
                   
               
               
                 Backstraps 
                   
                 Backstraps 
                   
               
               
                   
               
               
                 1 
                   3′6″ 
                 1 
                  3′4″ 
               
               
                 2 
                   4′2″ 
                 2 
                  5′ 
               
               
                 3 
                   4′8″ 
                 3 
                  6′4″ 
               
               
                 4 
                   4′8″ 
                 4 
                  7′11″ 
               
               
                 5 
                   4′2″ 
                 5 
                  9′6″ 
               
               
                 6 
                   3′6″ 
                 6 
                  4′6″ 
               
               
                 7 
                   4′3″ 
                   
                   
               
               
                 8 
                   5′2″ 
                   
                   
               
               
                 9 
                   6′5.5″ 
                   
                   
               
               
                 Set Back 
                   
                   
                   
               
               
                 1 
                   1′5″ 
                   
                   
               
               
                 2 
                   2′1″ 
                   
                   
               
               
                 3 
                   3′6″ 
               
               
                   
               
               
                   
                 Distance between 
                   
                 Distance between 
               
               
                 Backstraps 
                 backstraps at Bar 0 
                 Backstraps 
                 backstraps at Bar 0 
               
               
                   
               
               
                 0-1 
                 0.5″ 
                 0-1 
                  1′1″ 
               
               
                 1-2 
                   1′ 
                 1-2 
                  1′4″ 
               
               
                 2-3 
                   1′ 
                 2-3 
                  1′4″ 
               
               
                 3-4 
                   1′ 
                 3-4 
                  1′4″ 
               
               
                 4-5 
                   1′ 
                 4-5 
                  1′4″ 
               
               
                 5-6 
                   1′ 
                 5-6 
                  1′1″ 
               
               
                 6-7 
                   9″ 
                   
                   
               
               
                 7-8 
                   9″ 
                   
                   
               
               
                 8-9 
                   9″ 
               
               
                   
               
            
           
         
       
     
     Embodiments of the present invention, as shown in  FIGS. 4 and 6 , are suitable for use with low-profile trawls (LPT), which have limited head rope height that translates into a vertically compressed fishing circle in the body with flat top and bottom bellies and results in a rectangular fishing circle extending as far back as the tail of the net ahead of the cod end. Exemplary low-profile trawls include flat net shrimp trawl, scraper trawls, and the like. The semicircular shape of lead ring  406  allows for the sides of lead ring  406  to spread out and open the face of grid  302 , and vertically compress the shape of marine species sorting apparatus  400  to compliment the shape of the LPT at an installation site located within the tail of LPT. The semicircular shape of lead ring  406  further allows for the top of the extension section of LPT to stretch and flatten, which levels the leading edge of the LPT opening to allow the flap to lay flat and cover the opening with a tight seal. 
       FIG. 8  illustrates a marine species sorting apparatus  800  in accordance with a third embodiments of the present invention, including a lead ring  806  formed by two cables  806   a  and  806   b  located along the sides of grid  802  to provide a base for anchoring back straps  804  to lead ring  806  along sides of grid  802 , as shown in  FIG. 8 . Each end of back strap  804 - 5  is secured to top ends of lead ring cables  806   a  and  806   b , respectively, and the bottom ends of bars  808  are secured to back strap  804 - 1  to form lead ring  806  that is open at the top and bottom, as further shown in  FIGS. 8 and 9 .  FIG. 9  illustrates an exemplary layout representing half grid of marine species sorting apparatus  800 . Table 3 provides exemplary dimensions of back straps, bars, lead ring, bar spacings, and back strap spacings along the center bar for the exemplary embodiment (Type II-iii) shown in  FIG. 9 . 
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 Type II-iii Cable 
               
               
                 Grid (FIGS. 8-9) 
               
            
           
           
               
               
            
               
                 Cable Type 
                 Cable Length 
               
               
                   
               
               
                 Lead Ring 
                  7′ 
               
               
                 Sides 
                  3′6″ 
               
               
                 Bars 
                   
               
               
                 0 
                  6′8″ 
               
               
                 1 
                  6′6″ 
               
               
                 2 
                  6′6″ 
               
               
                 3 
                  6′5″ 
               
               
                 4 
                  6′3″ 
               
               
                 5 
                  6′ 
               
               
                 6 
                  5′ 
               
               
                 7 
                  4′2″ 
               
               
                 8 
                  3′9″ 
               
               
                 Backstraps 
                   
               
               
                 1 
                  3′4″ 
               
               
                 2 
                  6′ 
               
               
                 3 
                  7′4″ 
               
               
                 4 
                  9′2″ 
               
               
                 5 
                 12′ 
               
               
                 6 
                  4′6″ 
               
               
                   
               
               
                   
                 Distance 
               
               
                   
                 between 
               
               
                 Backstraps 
                 backstraps 
               
               
                   
               
               
                 0-1 
                  1′6.5″ 
               
               
                 1-2 
                  1′4″ 
               
               
                 2-3 
                  1′4″ 
               
               
                 3-4 
                  1′4″ 
               
               
                 4-5 
                  1′4″ 
               
               
                 5-6 
                  1′2″ 
               
               
                   
               
            
           
         
       
     
       FIG. 10  illustrates an alternate embodiment of the present invention for sorting marine species having a flat horizontal shape, including various varieties of flounders. Exemplary varieties of flounders include  Paralicthys dentatus, Pleuronectes  sp., and the like. As shown in  FIG. 10 , two cable grids  1002  and  1004  are oriented on its side and connected to form a V-shaped grid. Cable grids  1002  and  1004  include bars  1006  and  1008  that are anchored to vertical back straps  1014  and  1016  and are oriented in horizontal direction with sufficient bar spacing to allow the passage of flat marine species. Marine species that do not pass through bars  1006  are discharged from the trawl net through grid openings positioned on the sides of trawl net. In one embodiment of the present invention, cable grids  1002  and  1004  is made from two panels with each panel having a length of about 5 feet and a height of about 3 feet. Cable grids  1002  and  1004  are connected at the center by a vertical lead center post  1010 . In one embodiment of the present invention, cable grids  1002  and  1004  are connected at the center by anchoring bars  1006  to vertical lead center post  1010 . Vertical lead center post  1010  is further connected to lead ring  1012 . In one embodiment of the present invention, lead ring  1012  is rectangular shaped and is suitable for use with a LPT having four seams at the tail of the net. Bars  1006  and  1008  are secured to back straps  1014  and  1016 , respectively, at predetermined locations on back straps  1014  and  1016  to maintain consistent bar spacing for a predetermined grid layout. Back straps  1014  and  1016  are positioned perpendicular to bars  1006  and  1008 , and parallel to each other, with a predetermined space between each other and with a degree of offset. Setbacks  1018  between cable grids  1002  and  1004  and lead ring  1012  are used to support cable grids  1002  and  1004  in a V-shape. Setbacks  1018  are positioned using substantially same spacing used to position back straps  1014 . Setbacks  1018  are anchored to cable grids  1002  and  1004  and lead ring  1012  using terminal couplers  1020 , as shown in  FIG. 11 .  FIG. 11  illustrates an exemplary layout representing half grid of marine species sorting apparatus  1000 . Terminal couplers  1020  may be used to anchor back straps  104  or bars  108  to cable grids  1002  and  1004 . Terminal couplers  1020  may also be used to anchor setbacks  1018  to lead ring  1012 . In one embodiment of the present invention, terminal couplers  1020  having two open ends are used to anchor setbacks  1018   a  and  1018   b  to lead ring  1012 , as shown in  FIG. 10 . Table 4 provides exemplary dimensions of back straps, bars, lead ring, bar spacings, and back strap spacings for the exemplary embodiment (Type III) shown in  FIG. 11 . 
     
       
         
           
               
             
               
                 TABLE 4 
               
             
            
               
                   
               
               
                 Type III Cable 
               
               
                 Grid (FIGS. 10-11) 
               
            
           
           
               
               
            
               
                 Cable Type 
                 Cable Length 
               
               
                   
               
               
                 Lead Ring 
                  6′ 
               
               
                 Setbacks 
                   
               
               
                 1 
                 17″ 
               
               
                 2 
                 34″ 
               
               
                 3 
                 48″ 
               
               
                 Bars 
                   
               
               
                 0 
                 72″ 
               
               
                 1 
                 73″ 
               
               
                 2 
                 75″ 
               
               
                 3 
                 77″ 
               
               
                 4 
                 78″ 
               
               
                 5 
                 77″ 
               
               
                 6 
                 75″ 
               
               
                 7 
                 73″ 
               
               
                 8 
                 72″ 
               
               
                   
               
               
                 Bars 
                 Bar Spacing 
               
               
                   
               
               
                 0-1 
                  6″ 
               
               
                 1-2 
                  6″ 
               
               
                 2-3 
                  4″ 
               
               
                 3-4 
                  4″ 
               
               
                 4-5 
                  4″ 
               
               
                 5-6 
                  4″ 
               
               
                 6-7 
                  4″ 
               
               
                 7-8 
                  4″ 
               
               
                 Center Post 
                 36″ 
               
               
                 Backstraps 
                   
               
               
                 1 
                 36″ 
               
               
                 2 
                 36″ 
               
               
                 3 
                 36″ 
               
               
                   
               
            
           
         
       
     
     In embodiments of the present invention, floats  1202  can be used to provide buoyancy to marine species sorting apparatus in accordance with embodiments of the present invention, as illustrated in  FIG. 12  for Types I and II marine species sorting apparatus. In marine species sorting apparatus in accordance with embodiments of the present invention, from about 50% to about 75% of the weight of the cable used is complimented with buoyancy to help the apparatus achieve a neutral position in the profile of the trawl net. Floats  1202  are secured to bars  1204  and are positioned at predetermined locations on cable grid  1206  to provide buoyancy to cable grid  1206  and to prevent twisting of net during deployment and during operation of the trawl. In one embodiment of the present invention, floats  1202  are positioned in an area that represents the horizontal catenary of back straps  1208  and an area furthest away from any trawl webbing support, as shown in  FIG. 12 . In another embodiment of the present invention, floats  1202  are secured to bar  1204 - 0  from top of bar  1204 - 0  to at least midline of cable grid  1206  and to back strap  1208 - 0 . 
     Marine species sorting apparatus  100  in accordance with embodiments of the present invention is installed into a tube of webbing called an extension having dimensions capable of fitting to the trawl. Cable grid  102  is sewn to extension webbing to secure cable grid  102  to the extension. Lead ring  106  is secured to the fishing circle along a straight row of meshes perpendicular to the direction the trawl is pulled when fishing. Lead ring  106  is positioned towards the front of the trawl and the opening for allowing undesired marine species to exit grid  102  is positioned towards the back or cod end of the trawl. Back straps  104  are secured to the top quarter of the extension. Location where the apex of back straps  104  are secured to extension will determine the angle of grid  102  and the shape of opening at the posterior end of grid  102 . The area of the extension webbing within the apex of back strap  104 , and ahead of grid  102 , will define the escape opening. Opening in the webbing is cut at the end of grid  102  that is farthest from lead ring  106 , or at the posterior end of grid  102 , and back straps  104  are secured to the extension. 
     During typical operation of marine species sorting apparatus  100  installed within the trawl deployed for fishing, marine species entering the trawl are directed to marine species sorting apparatus  100  within the extension section of the trawl for sorting. Target marine species that are smaller than the bar spacing of bars  108  are directed through the bar spacing into the tail end of the trawl. The slope of grid  102  will direct marine species that are larger than the bar spacing of bars  108  through opening at the posterior end of grid  102  cut in the extension webbing of trawl. 
       FIG. 13  illustrates a marine species sorting apparatus  1300  in accordance with an alternate embodiment of the present invention, including a lead ring  1302  secured to grid frame  1304 . Grid frame  1304  includes a rectangular section  1304   a  with curved sections  1304   b - c  at the top and bottom of rectangular section  1304   a , as shown in  FIG. 14 . In one embodiment of the present invention, the length of rectangular section  1304   a  is about 96 inches. Grid frame  1304  surrounds a grid including a plurality of bars  1306  and back straps  1308  arranged in a predetermined layout, as shown in  FIGS. 13 and 14 , with each bar having a predetermined length and separated from each other by a predetermined bar spacing. In one embodiment of the present invention, the spacing between bars  1306  is about 6 inches. In the embodiment as shown in  FIGS. 13 and 14 , bars  1306  are arranged in a symmetrical layout on either side of a center bar  1306 - 0  extending along a direction substantially traversing longitudinal axis of grid frame  1304 . Bars  1306 - 1  are positioned next to bar  1306 - 0  and bars  1306 - 2  are positioned farthest away from bar  1306 - 0 , as shown in  FIG. 14 . In the embodiment shown in  FIGS. 13 and 14 , bar  1306 - 0  is the longest bar and bars  1306 - 2  are the shortest bars. Each end of bars  1306  are secured to grid frame  1304 . In some embodiments of the present invention, a plurality of floats are secured to bars  1306  at predetermined locations to provide buoyancy to apparatus  1300 . Back straps  1308  are positioned perpendicular to bars  1306 , and parallel to each other with a predetermined space between each other and with a degree of offset. Parallel back straps  1308  with consistent distance between them are obtained by securing back straps  1308  to bars  1306 . Each end of back straps  1308  are secured to grid frame  1304 . In the layout shown in  FIGS. 13 and 14 , back straps  1308  are equal length. In one embodiment of the present invention, the length of each back strap  1308  is about 40 inches. In an exemplary embodiment in accordance with the present invention, the distance between the back straps  1308  is about 24 inches. In some embodiments of the present invention, back strap  1308 - 2  located at the center of grid frame  1304  includes two cables combined to form a single back strap, as shown in  FIG. 14 . 
     Lead ring  1302  includes a first curved section  1302   a , a second curved section  1302   b  and a straight section  1302   c , as shown in  FIG. 13 . In one embodiment of the present invention, back strap  1308 - 0  forms the straight section  1302   c  of lead ring  1302 . One end of first curved section  1302   a  and one end of second curved section  1302   b  are each secured to straight section  1302   c  and grid frame  1304 . In one embodiment of the present invention, one end of curved section  1302   a  and curved section  1302   b  are each secured to straight section  1302   c  and grid frame  1304  using a four-way ( 4 W) knuckle. 
     Setbacks  1310  between grid frame  1304  and lead ring  1302  form side panels that are used to support grid frame  1304  in a desired shape.  FIG. 15  illustrates an exemplary layout representing a side panel formed by lead ring  1302 , grid frame  1304  and setbacks  1310 . In an embodiment of the present invention, setbacks  1310  are made of 6×19 stainless steel cables. Setbacks  1310  are positioned using substantially same spacing used to position back straps  1308 . Setbacks  1310 - 1  through  1310 - 3  are anchored to grid frame  1304  and lead ring  1302  using terminal couplers. Setbacks  1310 - 4  are secured to the distal ends of curved sections  1302   a  and  1302   b  and to back strap  1308 - 4  and grid frame  1304 , as shown in  FIGS. 13 and 15 . In one embodiment of the present invention, setbacks  1310 - 4  are secured to the distal ends of curved sections  1302   a  and  1302   b  and to back strap  1308 - 4  and grid frame  1304  using four-way ( 4 W) knuckles. The shape of each side panel is set by varying the lengths of setbacks  1310 . Lengths of setbacks  1310  decreases from setback  1310 - 1  to setback  1310 - 4  such that the plane of lead ring  1302  is set at a predetermined angle with the plane of grid frame  1304 , as shown in  FIGS. 13 and 15 . In one embodiment of the present invention, the lengths of setbacks  1310  are set such that the angle between the plane of lead ring  1302  and the plane of grid frame  1304  is about 30 degrees. Table 5 provides exemplary dimensions of back straps, bars, lead ring, setbacks, bar spacings, and back strap spacings for an exemplary embodiment in accordance with the present invention, as shown in  FIGS. 13, 14 and 15 . 
     
       
         
           
               
             
               
                 TABLE 5 
               
             
            
               
                   
               
               
                 Suri TII 2.0 Grid 
               
            
           
           
               
               
               
            
               
                   
                 Cable Type 
                 Cable Length 
               
               
                   
                   
               
               
                   
                 Lead Ring 
                   
               
               
                   
                 1302a 
                   48″ 
               
               
                   
                 1302b 
                   48″ 
               
               
                   
                 Grid Frame 
                   
               
               
                   
                 1304b 
                   48″ 
               
               
                   
                 1304c 
                   48″ 
               
               
                   
                 Bars 
                   
               
               
                   
                 1306-0 
                   120″ 
               
               
                   
                 1306-1 
                   116″ 
               
               
                   
                 1306-2 
                   108″ 
               
               
                   
                 Backstraps 
                   
               
               
                   
                 1308-0 
                   40″ 
               
               
                   
                 1308-1 
                   40″ 
               
               
                   
                 1308-2 
                   40″ 
               
               
                   
                 1308-3 
                   40″ 
               
               
                   
                 1308-4 
                   40″ 
               
               
                   
                 Set Back 
                   
               
               
                   
                 1310-1 
                 20.75″ 
               
               
                   
                 1310-2 
                  41.5″ 
               
               
                   
                 1310-3 
                 62.28″ 
               
               
                   
                 1310-4 
                 83.16″ 
               
               
                   
                   
               
               
                   
                   
                 Distance 
               
               
                   
                 Bars 
                 between Bars 
               
               
                   
                   
               
               
                   
                 1306-0-1306-1 
                    6″ 
               
               
                   
                 1306-1-1306-2 
                    6″ 
               
               
                   
                 1306-2-1306-3 
                    6″ 
               
               
                   
                   
               
               
                   
                   
                 Distance 
               
               
                   
                   
                 between 
               
               
                   
                   
                 backstraps  
               
               
                   
                 Backstraps 
                 at Bar 1306-0 
               
               
                   
                   
               
               
                   
                 1308-0-1308-1 
                   24″ 
               
               
                   
                 1308-1-1308-2 
                   24″ 
               
               
                   
                 1308-2-1308-3 
                   24″ 
               
               
                   
                 1308-3-1308-4 
                   24″ 
               
               
                   
                   
               
            
           
         
       
     
     Lead ring  1302  supports grid frame  1304  and secures marine species sorting apparatus  1300  in trawl webbing via a lead extension panel  1312  and a transition piece webbing  1314 , as shown in  FIG. 16 . Lead ring  1302  and grid frame  1304  are located inside a grid frame extension webbing  1316 . In an embodiment of the present invention, grid frame extension webbing  1316  is a high tenacity polyethylene (HTPE) fiber webbing having a mesh size of about 120 millimeters and an area of about 25×25 mesh. A mesh is typically comprised of four bars in the shape of a diamond and bars are typically about half the length of a stretched mesh. Exemplary webbing that can be used for grid frame extension webbing  1316  include 120 millimeter K/K 4 millimeter Euroline® webbing. Lead extension panel  1312  is formed by extending grid frame extension webbing  1316  beyond lead ring  1302 . In one embodiment of the present invention, lead extension panel  1312  is formed by extending grid frame extension webbing  1316  beyond lead ring  1302  by about four mesh. 
       FIG. 17  illustrates exemplary webbing panels for grid frame extension webbing  1316  and transition piece webbing  1314 . Transition piece webbing  1314  includes two top side panels  1314   d , two bottom side panels  1314   e , a bottom belly panel  1314   f  and top belly panel  1314   g , as shown in  FIG. 17 . In one embodiment of the present invention, bottom belly panel  1314   f  is a 80 millimeter diameter webbing having a width of about 116 mesh at the leading edge and tapers to about 46 mesh as it enters grid frame  1304  such that the length of each side edge of bottom belly panel  1314   f  is about 82 bars. In an embodiment of the present invention, top belly panel  1314   g  has a width of about 120 mesh at the leading edge and tapers to about 50 mesh at the edge adjacent to lead extension panel  1312  such that the length of top belly panel  1314   g  is about 30 mesh with each side having a length of about 60 bars. Top belly panel  1314   g  edge adjacent to lead extension panel  1312  includes a wedge shaped gap having a ratio of wedge width to wedge height at about 1:2 such that the distance between the apex of the wedge and the leading edge of top belly panel  1314   g  is about 5 mesh. In an embodiment of the present invention, top side panel  1314   d  and bottom side panel  1314   e  each have a width of about 5 mesh at the leading edge and expands to about 22.5 mesh at the edge adjacent to lead extension panel  1312 . In the exemplary configuration shown in  FIG. 17 , bottom belly panel  1314   f  can have about 40% more strain than the top belly panel  1314   g  allowing bottom belly panel  1314   f  to be tight, flat and level, and directing the water flow towards grid frame  1304 . Top belly panel  1314   g  would be slack and ballooning in comparison allowing the excess water flow to pass through the open webbing meshes as the marine species are collected and directed through the bars. 
     Transition piece webbing  1314  panels are secured using eight gore lines that transition the shape of trawl from a two-seam trawl to four-seam trawl, as shown in  FIG. 16 . This can be achieved with six gore lines starting from the forward middle point of transition piece webbing  1314  with two top transition gore lines  1314   a , one for each side of transition piece webbing  1314 , secured to the top corners of lead ring  1302  on its respective sides, with two bottom transition gore lines  1314   b , one for each side of transition piece webbing  1314 , secured to the bottom corners of lead ring  1302  on its respective sides, and with two midline reduction gore lines  1314   c , one for each side of transition piece webbing  1314 , secured to lead ring  1302  and setback  1310 - 2  on its respective sides, as shown in  FIG. 16 . Transition piece webbing  1314  transitions the vertically compressed fishing circle of the two-seam trawl to a symmetrical fishing circle that better supports the round shape of lead ring  1302 . Midline reduction gore line  1314   c  located between top side panel  1314   d  and bottom side panel  1314   e  on transition piece webbing  1314  and a midline reduction gore line  1318   a  located at the intersection of the top and bottom belly panels of the tail  1318  of the two-seam trawl reduce the mesh count of the fishing circle. 
     Bottom belly  1314   f  of transition piece webbing  1314  forms a ramp, as shown in  FIG. 18 , that is capable of directing the catch and water towards the top half of grid frame  1304 . Bottom belly  1314   f  includes two half webbing panels and each half webbing panel is secured along its leading edge  1314   h , as shown with “x” in  FIG. 18 , with an offset seam to the bottom belly at the tail of a two-seam trawl.  FIG. 19  illustrates an exemplary half webbing panel for bottom belly  1314   f . Side edge  13141  of each panel of bottom belly  1314   f  includes bars extending from the leading edge of transition piece webbing  1314  to back strap  1308 - 2  along midline reduction gore line  1314   c , and along a lead extension panel  1312  and setback  1310 - 2  of a side panel of grid frame  1304 . Side edge  13141  of bottom belly  1314   f  is secured to between top side panel  1314   d , bottom side panel  1314   e  and midline reduction gore line  1314   c  starting from leading edge of transition piece webbing  1314 , to setback  1310 - 2 , and to a portion of grid frame  1304  starting from setback  1310 - 2  to setback  1310 - 4  of a side panel of grid frame  1304 , as further shown in  FIG. 18 .  FIG. 19  further illustrates locations where an exemplary half webbing panel for bottom belly  1314   f  is secured to transition piece webbing  1314  panels, setback  1310 - 2  and grid frame  1304 . In one embodiment of the present invention, side edge  13141  of each panel of bottom belly  1314   f  is about 82 bars with 54 bars secured to midline reduction gore line  1314   c,  10 bars extending into lead extension panel  1312  and 18 bars secured to setback  1310 - 2 . 
     Bottom belly  1314   f  extends inside the grid extension webbing to form a ramp when grid frame  1304  is held inline by the gores as the trawl is being towed and transitions into a flap  1314   j  as it reaches grid frame  1304 . Flap  1314   j  is secured to grid frame  1304  until an opening at the posterior end of grid frame  1304 . In one embodiment of the present invention, flap  1314   j  is sewn along grid frame  1304  until the opening at the posterior end of grid frame  1304  and further sewn to grid frame  1304  webbing by no more than 3 mesh beyond grid frame  1304 . Flap  1314   j  extends for a predetermined length beyond the opening at the posterior end of grid frame  1304 . In one embodiment of the present invention, flap  1314   j  extends for about 2 feet beyond the opening at the posterior end of grid frame  1304 . In one embodiment of the present invention, bottom belly  1314   f  is about 116 inches wide along leading edge  1314   h  and about 43 inches wide at the tail of flap  1314   j.    
     During typical operation of marine species sorting apparatus  1300  installed within the trawl deployed for fishing, marine species entering the trawl are directed towards the top half of grid frame  1304  while allowing the bottom half of grid frame  1304  to drop below the fishing circle. As the marine species passes through the top half of grid frame  1304  the bottom half of grid frame  1304  secures flap  1314   j  to maximize catch retention. 
     Apparatus in accordance with embodiments of the present invention has several advantages over previous marine species sorting apparatus. More particularly, marine species sorting apparatus in accordance with embodiments of the present invention has more flexibility than a rigid grid system, which forces a trawl to conform to the shape of the grid to work properly. More specifically, marine species sorting apparatus can conform to the dynamic properties of the trawl and the changing stresses the trawl endures. A rigid grid will break before it bends and cannot be easily packed into a net reel. The use of cables into a sorting grid system, as shown in embodiments of marine species sorting apparatus, provides flexibility and simplifies the process of packing marine species sorting apparatus onto a net reel. A significant advantage of marine species sorting apparatus in accordance with embodiments of the present invention is the ability of the grid to hold its shape while being dynamic, flexing and adjusting to the tension in the trawl webbing, and transform its shape with the shape of the trawl. 
     Marine species sorting apparatus in accordance with embodiments of the present invention can be adapted to a variety of configurations suitable for selective trawl fishing. Construction of grid, as described herein, provides flexibility to vary the shape of marine species sorting apparatus to fit specific trawl shapes. It is thought that marine species sorting apparatus of the present invention and many of its attendant advantages will be understood from the foregoing description and it will be apparent that various changes may be made in the form, construction arrangement of parts thereof without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the form hereinbefore described being merely a preferred or exemplary embodiment thereof.