The following relates to devices and methods for flipping or rotating a floating aquatic cage to mitigate biofouling and for farm management, such as to carry out maintenance and facilitate harvesting, particularly with the style of floating cage used in farming oysters and other shellfish.
Oyster farming is carried out using a variety of methods. In Eastern Canada, the Canadian west coast and northeastern regions of the United States, a suspended culture technique is used in which oysters are held inside floating cages. An example of this system is shown in
In winter, the cages are lowered to the bottom where they are protected from the ice. In the example shown in
There are many different types of marine life which can cause bio-fouling, from microscopic bacteria to larger plants, crustaceans and mollusks, such as seaweed, barnacles and mussels. If bio-fouling is allowed to persist and grow, the oysters must compete with the other plant and animal life for resources which can cause a reduction in growth rate, prolonged growing times and longer wait times to harvest. Bio-fouling can also affect the shape and size of the oysters, and generally reduce product quality and profit margins for the oyster farmers. Antifouling is therefore a key part of oyster farming as it yields a higher volume, better shaped and larger product, thereby increasing market value.
To address the need for antifouling and to carry out regular maintenance, systems have been developed which allow for the cages to be flipped and be either submerged in, or float on top of the water. Antifouling occurs once the cages are flipped out of the water to dry. The cage flipping is a critical step in the oyster farming process, yet can be an arduous task.
After a period of time, typically around ten days, the oyster farmer must flip the cages, a process that allows sunlight and air to kill any bacteria that may have formed on the oysters. This is typically done by hand, and will usually require two workers standing in the water to manually flip each (e.g. 90 kg) cage one at a time. For a large farming operation with many cages this represents a significant amount of work.
Different approaches have been developed to ease the work load required to effectively farm oysters and other shellfish species.
EP 0 681 783 describes a cage for rearing oysters which consists of a series of compartments, each designed to receive a bag of shellfish, and which is pivoted about axles resting on supports equipped with locking mechanisms to fix the cage in position. The cage sides and end walls are made from a large-size mesh to allow a free exchange between the inside of the cage and its outer environment.
U.S. Pat. No. 5,438,958 discloses an open water mariculture facility including a central platform/support structure from which a plurality of cylindrical, ballastable cage structures emanate for containing and maintaining a marine species. The ballastable cages can be raised for maintenance, and the system provides a rolling system for turning the cages on demand.
These prior systems are not well adapted for use in a floating cage system with such a large number of cages in series. Rather, these are stationary systems that only allow rotation about a centrally disposed axis.
The need therefore still exists to facilitate flipping such a large number of floating cages. The ideal cage flipper design should ideally be encompassed within or at least mountable on a fishing boat, avoid tangling of the cage tether lines, and have suitable properties to maintain buoyancy and stability of the boat.
An aspect relates to a device for flipping or rotating a floating aquatic cage used in shellfish farming, particularly oyster farming.
According to an aspect of embodiments of the present invention there is provided a device for rotation of a floating aquatic cage. The device comprises a hollow cylindrical frame or housing defining a path through which the floating aquatic cage may pass, including entrance and exit openings; a guide assembly affixed to the entrance of the hollow cylindrical frame or housing to receive and guide the floating aquatic cage inside the device; a spiral path formed in a sidewall of the hollow cylindrical frame or housing and through which a tether line attached to the floating aquatic cage may pass; and a plurality of helical guide elements positioned on an inside surface of the hollow cylindrical frame or housing and dimensioned to form an obstruction to opposing corners of the floating aquatic cage, and to impart a helical turning force in such a manner as to rotate the floating aquatic cage along a length of the hollow cylindrical frame or housing from the entrance opening to the exit opening.
In certain non-limiting embodiments of the device, the hollow cylindrical frame or housing may include a support beam (11), a plurality of ring structures (12a) affixed along a length of the support beam (11) to form a cylindrical arrangement; a bumper (13) affixed along a side of the device to at least one of the ring structures (12a); and a sidewall (22) affixed along the inside of the ring structures (12a) and forming at least a partial interior surface inside the device (10).
In further non-limiting embodiments, the guide assembly may include a frame (14) mounted to the support beam (11) at the entrance end of the hollow cylindrical frame or housing, including top, side and bottom portions (14a,b,c,d); outwardly flaring cage guides (15,17) mounted on the side portions (14b,c) of the frame (14); and outwardly flaring tether line guides (16,18) spaced apart and mounted to the bottom portion (14d) of the frame (14), the tether line guides (16,18) forming the opening of the spiral path (20).
The spiral path (20) may, in further embodiments, include bands (21a,b), which are continuous with the tether line guides (16,18) and extend along the spiral path (20), starting at the bottom of the device (10) within the guide assembly (14,15,16,17,18) and ending at or near the top of the device (10) at the exit opening.
According to a further aspect of embodiments of the present invention there is provided a device for rotation of a floating aquatic cage. The device comprises a hollow frame or housing defining a path through which the floating aquatic cage may pass, including entrance and exit openings; and a guide element positioned on an inside surface of the hollow frame or housing and dimensioned to form an obstruction to at least one corner of the floating aquatic cage, and to impart a turning force in such a manner as to rotate the floating aquatic cage along a length of the hollow frame or housing from the entrance opening to the exit opening. In some embodiments, a guide assembly may affix to the entrance of the hollow frame or housing to receive and guide the floating aquatic cage inside the device.
In certain non-limited embodiments, the device comprises one or more support beams (11), a plurality of support structures (12) affixed along a length of the one or more support beams (11), the plurality of support structures arranged to form a top and two opposing sides; a plurality of guide element supports extending between the guide element and at least one of the plurality of support structures; and an at least one sidewall (22) affixed along the inside of the support structures (12) and forming at least a partial interior surface inside the device (10). In some embodiments, a bumper (13) may be affixed along the inner surface of the device to contact the floating aquatic cage during rotation.
In certain non-limited embodiments, the guide elements rotate the floating aquatic cage at least 65 degrees from a horizontal plane defined by a surface of the water.
In certain non-limited embodiments, the guide element may form a continuous ramp that rises or inclines from the entrance opening toward the exit opening. The continuous ramp may be curvilinear, linear, or helical. The guide element may remain stationary relative to the hollow frame or housing when it imparts its helical turning force.
It is also envisioned that further embodiments of the device may include a boat mounting system. For example, such a boat mounting system may include a plurality of boat mounting brackets (30), each including a height adjustable sleeve portion (32); and an equal number of mounting posts (31) affixed to a surface of the hollow cylindrical frame, the mounting posts (31) being dimensioned to receive the height adjustable sleeve portions (32) of the boat mounting brackets (30) and removably connect the boat mounting brackets (30) to the hollow cylindrical frame. The mounting posts may form part of the hollow cylindrical frame or housing. Some embodiments of the device may also include receiving brackets (35) for mounting to the gunwale (36) of the boat (37). The receiving brackets (35) will ideally be dimensioned to receive and affix the boat mounting brackets (30) to the boat.
The receiving brackets (35), in further embodiments of the device, may be adjustable horizontally. For example, the boat mounting brackets (30) may include a substantially horizontal portion with a plurality of holes, wherein a corresponding set of holes are formed in the receiving brackets (35). These holes provide a horizontally adjustable mechanism for connecting the device to the boat, e.g. using bolts or other appropriate fastening device.
In addition, the height adjustable sleeve portions (32) of the boat mounting brackets (30) may include holes (40) formed along the vertical axis thereof, with a corresponding set of holes (41) formed along the vertical axis of the mounting posts (31). These holes (40,41) provide a height adjustable mechanism for raising or lowering the height of the device on a boat.
In some embodiments, the boat mounting brackets may form a pivotal connection with the receiving brackets. The device may pivot, on a pivot axis defined by the pivotal connection, between a deployed position and a stowed position. The boat mounting system may comprise a boat cushion connected to one or more of the plurality of boat mounting brackets. The boat cushion may connect to the boat mounting bracket by a pivotal connection.
According to a further aspect of embodiments of the present invention there is provided a device for rotation of a floating aquatic cage. The device comprises a plurality of float elements; a hollow cylindrical frame or housing mounted to the plurality of float elements, the hollow cylindrical frame or housing and float elements arranged to define a path through which the floating aquatic cage may pass, including entrance and exit openings; and a guide element positioned on an inside surface of the hollow cylindrical frame or housing and dimensioned to form an obstruction to one side of the floating aquatic cage, and to impart a turning force in such a manner as to rotate the floating aquatic cage along a length of the hollow cylindrical frame or housing from the entrance opening to the exit opening.
In certain non-limited embodiments, the float elements may define a guide assembly located near or at the entrance of the hollow cylindrical frame or housing to receive and guide the floating aquatic cage inside the device. The guide element may be structured to rotate at least part of the aquatic cage onto a top surface of one of the plurality of float elements. The device may comprise a line hauler structured to contact a tether line. The float elements may be pontoons.
Some of the embodiments will be described in detail, with references to the following Figures, wherein like designations denote like members, wherein:
Described herein is a floating aquatic cage rotation device which can be used in the management of shellfish farming cages, such as oyster cages, including but not limited to defouling, maintenance and harvesting procedures.
As illustrated in
In some embodiments, the hollow frame or housing may define a path through which the floating aquatic cage may pass. The path of the aquatic cage may include entrance and exit openings. As illustrated in
As shown in
Guide assembly (14,15,16,17,18) is provided at the mouth of the device (10) to guide the floating cages and the tether lines inside the device, when mounted to the side of a boat, during a drive-by operation. One example of the guide assembly is shown in detail in
The spiral path (20) can be seen in greater detail in
A sidewall (22) is affixed along the inside of the support structures (12). The sidewall (22) may include a full enclosure of the support structures, although in preferred embodiments will include only a partial enclosure in order to minimize weight. It serves to further strengthen the apparatus and at the same time prevent the cage from escaping or getting caught between the support structures (12) as it passes through the device (10). As shown in
As shown in
A guide element (20) may be positioned on an inside surface of the hollow frame or housing and dimensioned to form an obstruction to at least one corner of the floating aquatic cage. The guide element may impart a turning force in such a manner as to rotate the floating aquatic cage along a length of the hollow frame or housing from the entrance opening to the exit opening. Guide element (20) may rotate the floating aquatic cage to a sufficient degree, such as at least 65 degrees, from a horizontal plane defined by a surface of the water. Full rotation of the cage may be assisted by the one or more bumpers (13) or sidewalls (22). As illustrated in
The guide element (20) may have a suitable shape, such as helical (
As illustrated in
As illustrated in
In operation, as can be seen in
It is also envisioned that various modifications and optional adaptations of the disclosed device may be made, either to adapt to location, equipment or procedural requirements.
As illustrated in
Device (10) may form part of a pontoon boat. The pontoon boat may allow oyster cages to pass through a center path. The pontoon boat may permit easier and more comfortable access to cages from both sides of the tether line. A line hauler may be used for moving the boat forward, and keep it straight. The design as shown in
In addition, in certain embodiments the cage guides may be made of a suitable material, such as shaped aluminum. The cage guides may be covered with a covering made of a suitable material, such as polyethylene. This covering can reduce the friction with the cage while it passes through the device, and thereby reduce the wear on the cages. The material used may be removable and replaceable as it wears down over time.
In addition, a guide may be added along both sides of the path (20), the sidewalls (22, 22a,b,c) or both, which may allow the rope to pass through the unit to reduce rope damage and minimize entanglement. The guide can also be removable and replaceable as it wears down over time. The guide may be made of a suitable material, such as polyethylene.
The device may be used for management or maintenance of an oyster farm. Maintenance of cages (1) may be considered as one or more of: emptying the cages, drying cages, harvesting oysters, flipping cages, and others. In some cases, the cages are partially flipped to provide a convenient access to the contents of the cages. Partially or fully rotated cages may be emptied of their contents or undergo maintenance as needed. As shown in
The device (10) may be made in various different dimensions, taking into account a number of factors including the size of the cages the device is to be used with, as well as the length of the boat, or simply to minimize weight, cost and/or transport/storage properties.
Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.
For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements.
This application claims priority to PCT Application No. PCT/CA2018/051067, having a filing date of Sep. 5, 2018, based off of U.S. Provisional Application No. 62/554,187 having a filing date of Sep. 5, 2017, the entire contents both of which are hereby incorporated by reference.
Filing Document | Filing Date | Country | Kind |
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PCT/CA2018/051067 | 9/5/2018 | WO |
Publishing Document | Publishing Date | Country | Kind |
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WO2019/046935 | 3/14/2019 | WO | A |
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0681783 | Nov 1995 | EP |
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Entry |
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International Search Report & Written Opinion dated Nov. 22, 2018 for PCT/CA2018/051067. |
Number | Date | Country | |
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20210000084 A1 | Jan 2021 | US |
Number | Date | Country | |
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62554187 | Sep 2017 | US |