WO2023139582A1

WO2023139582A1 - Intensive culture of benthic invertebrates

Info

Publication number: WO2023139582A1
Application number: PCT/IL2023/050059
Authority: WO
Inventors: Sagi Livne; Eran Hadas; Ehud FEITUCH
Original assignee: Eco Shrimp Ltd.
Priority date: 2022-01-19
Filing date: 2023-01-18
Publication date: 2023-07-27

Abstract

A culture tank for intensive culture of benthic invertebrates, the culture tank including plurality of submersible substrate stacks of polymeric substrates, a tilt mechanism operative to tilt the substrate stacks from a substantially horizontal growth position to a harvest position ranging up to 70° relative to the horizontal; a water treatment system for maintaining optimal growth conditions, and an air lift assembly for re- suspending feed particles without damaging the feed.

Description

INTENSIVE CULTURE OF BENTHIC INVERTEBRATES

TECHNICAL FIELD

[0001] The present invention relates generally to invertebrate aquaculture, and specially, optimizing growing conditions for maximum yield.

BACKGROUND

[0002] The world's population is increasing rapidly, causing a concurrent increase in demand for seafood. A variety of methods have been developed in attempts to bridge the gap between the supply and demand of food, particularly focused on seafood. For example, many different shellfish species are now produced in aquaculture. Some species are cultured during the complete life cycle whereas others are cultured from wild-harvested seed. Still others are raised in hatcheries and released to open water for later harvesting. Unfortunately, the environmental effect, cost in time and operation for producing marketable sized shellfish using current methods is very high.

[0003] Benthic invertebrates are multicellular organism ranging in length from several mm to around 50 cm and live at the bottom of water bodies. They live either on the surface of bedforms (e.g. rock, coral or sediment - epibenthos) or within sedimentary deposits (infauna). Benthic invertebrates comprise several types of feeding groups e.g. deposit-feeders, filter-feeders, grazers and predators. Replicating their natural bedforms or sedimentary deposits renders commercial production challenging.

[0004] There is a need for an improved system facilitating industrialized, intensive culture appropriate of benthic invertebrates.

SUMMARY

[0005] According to the teachings of the present invention there is provided a culture tank assembly for intensive culture of benthic invertebrates, the culture tank including: one or more submersible substrate stacks, each of the substrate stacks having a plurality of substantially horizontal substrates, each of the substrates disposed at an angle less than 10° from a horizontal plane; a substrate -stack frame, each of the substrates pivotally mounted to the frame; and a tilt mechanism configured to convey the substrate stack from the substantially horizontal position to a harvest position ranging between 30°-90° relative to the horizontal plane.

[0006] According to a further feature of the present invention, the substrate-stack frame is pivotally mounted to the frame mount. [0007] According to a further feature of the present invention, the tilt mechanism is operative to raise a distal end of the substrate-stack frame.

[0008] According to a further feature of the present invention, the assembly includes a substrate scaffold, wherein each of the substrates are mounted to a scaffold.

[0009] According to a further feature of the present invention, the substrate-stack frame includes a plurality of uprights, each of the uprights having a series of connection configurations, wherein each of the substrates scaffolds is pivotally mounted within the connection configurations.

[00010] According to a further feature of the present invention, the tilt mechanism is operative to raise proximal and distal ends of the substrate-stack frame.

[00011] According to a further feature of the present invention, the substrate-stack frames have a mechanical linkage linking a first substrate-stack frame to second substrate-stack frame.

[00012] According to a further feature of the present invention, the mechanical linkage is configured to raise a distal end of the second substrate-stack frame as a distal end of a first substrate-stack frame is raised.

[00013] According to a further feature of the present invention, the mechanical linkage is configured to raise a proximal end of the second substrate-stack frame as a distal end of a first substrate-stack frame is raised.

[00014] According to a further feature of the present invention, the substrates have a plurality of circulation slots facilitating fluid flow when submerged in liquid.

[00015] According to a further feature of the present invention, the circulation slots have an oval geometry.

[00016] According to a further feature of the present invention, there is also provided, a controller configured to activate the tilt mechanism responsively to a trigger event.

[00017] According to a further feature of the present invention, the trigger event is a time or an invertebrate size.

[00018] According to a further feature of the present invention, there is also provided, an air lift assembly configured to direct compressed air into an intake pipe so as create a suction drawing water into the intake pipe.

[00019] According to a further feature of the present invention, there is also provided, filter intake column in fluid communication with two sets of vertically aligned inlet ports of a water treatment facility, the two sets of vertically aligned inlet ports operative to create a plurality of horizontal circulation currents within a tank of the culture tank assembly. [00020] There is also provided according to the teachings of the present invention, a method for harvesting cultured benthic invertebrates, the method including tilting a submerged stack of substrates holding cultured benthic invertebrates to an angle causing the benthic invertebrates to fall off the substrates.

[00021] According to a further feature of the present invention, the tilting is responsive to a harvest time.

[00022] According to a further feature of the present invention, there is also provided, the trigger the tilting is responsive threshold size of a benthic invertebrate.

[00023] According to a further feature of the present invention, the angle is 30° or less relative to a horizontal plane.

[00024] According to a further feature of the present invention, there is also provided, returning the stack of substrates to a horizontal growth position.

BRIEF DESCRIPTION OF THE DRAWINGS

[00025] In the following detailed description, specific details are set forth to facilitate understanding of the invention; however, it should be understood by those skilled in the art that the present invention may be practiced without these specific details. Unless otherwise defined herein, scientific and technical terms shall have the meanings commonly understood by those of ordinary skill in the art. Well-known methods, procedures, and components have been omitted to highlight the invention. Moreover, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description.

[00026] FIG. 1 is a perspective, top-view of a plurality of substrate stacks deployed in a growth mode within a tank, according to an embodiment;

[00027] FIG. 2 is a perspective top-view of a single substrate stack in a growth mode linked to a tilt mechanism, according to an embodiment;

[00028] FIG. 3 is a perspective side-view depicting an enlarged cutaway of a substrate mechanically linked to a substrate-stack frame supported by a and a frame support structure, according to an embodiment;

[00029] FIG. 4 is a schematic, bottom-view of a single substrate and its substrate scaffold, according to an embodiment;

[00030] FIG. 5 is a perspective bottom-view depicting a mechanical linkage between the substrate scaffold and uprights of the stack frame, according to an embodiment; [00031] FIG. 6 is a perspective, side-view of a two mechanically linked substrate stacks in a harvest mode within a tank, according to an alternative embodiment;

[00032] FIG. 7 is a perspective, side-view of a two hinge-linked substrate stacks in a harvest mode within a tank, according to a variant alternative embodiment;

[00033] FIG. 8 is a perspective, top-view of a plurality of substrate stacks disposed in a growth mode and mechanically linked to a multi-stack frame within a tank, according to a second alternative embodiment;

[00034] FIG. 9 is a perspective, top-view of a plurality of substrate stacks disposed in a harvest mode and mechanically linked to a multi-stack frame within a tank, according to a second alternative embodiment;

[00035] FIG. 10 is a perspective, side-view of a culture tank with inflow and outflow ports of a water treatment system, according to an embodiment;

[00036] FIG. 11 is a perspective view of an air lift assembly depicting a primary water and air intake ports, feed distribution ports, and a collection basket, according to an embodiment;

[00037] FIG. 12 is an enlarged, cutaway perspective view of the air lift assembly depicting air and water intake ports, according to an embodiment;

[00038] FIG. 13 is a schematic depiction of a control managing the tilt mechanism, the water circulation system, and the air lift assembly, according to an embodiment; and [00039] FIG. 14 is a flowchart of the processing steps employed in automating the harvest, according to an embodiment.

DETAILED DESCRIPTION

[00040] The present examples set forth a culture tank for the intensive culture of benthic invertebrates. As noted above, replicating bedform or sedimentary deposit environments facilitating benthic invertebrate growth renders commercial production challenging. The subject examples provide submerged, tiltable stacked assemblies or substrate stacks providing significant area for growth and harvest without removing the growth surfaces from the water. The culture tank also includes a water dispenser in liquid communication with an external treatment system and an air lift assembly to advantageously replicate the necessary surface and environmental conditions facilitating industrialized, intensive culture of benthic invertebrates. It should be noted that the stacked substrate and the air lift assembly may each be used independently. [00041] Experimental work utilizing shrimp as sample benthic invertebrate has confirmed that the additional surface area provided by the stacked substrates advantageously increases yield thereby enabling large scale, intensive and industrialized shrimp culture facilities.

[00042] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[00043] As used herein, the singular forms "a," "an" and "the" are intended to include plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements components and/or groups or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups or combinations thereof. As used herein the terms "comprises", "comprising", "includes", "including", “having” and their conjugates mean "including but not limited to". The term “consisting of’ means “including and limited to”.

[00044] As used herein, the term "and/or" includes any and all possible combinations or one or more of the associated listed items, as well as the lack of combinations when interpreted in the alternative ("or").

[00045] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and claims and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein. Well-known functions or constructions may not be described in detail for brevity and/or clarity.

[00046] It will be understood that, although the terms first, second, etc., may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. Rather, these terms are only used to distinguish one element, component, region, layer and/or section, from another element, component, region, layer and/or section. [00047] It will be understood that when an element is referred to as being "on," "attached" to, "operatively coupled” to, “operatively linked” to, “operatively engaged” with, “connected" to, "coupled" with, "contacting," “added to” etc., another element, it can be directly on, attached to, connected to, operatively coupled to, operatively engaged with, coupled with, added to, and/or contacting the other element or intervening elements can also be present. In contrast, when an element is referred to as being "directly contacting" another element or “directly added” to another element, there are no intervening elements and/or steps present.

[00048] Whenever the term “about” is used, it is meant to refer to a measurable value such as an amount, a temporal duration, and the like, and is meant to encompass variations of ±20%, ±10%, ±5%, ±1%, or ±0.1% from the specified value, as such variations are appropriate to perform the disclosed methods.

[00049] Certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination or as suitable in any other described embodiment of the invention. Certain features described in the context of various embodiments are not to be considered essential features of those embodiments, unless the embodiment is inoperative without those elements.

[00050] Throughout this application, various embodiments of this invention may be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the invention. Accordingly, the description of a range should be considered to have specifically disclosed all the possible subranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range. [00051] Whenever a numerical range is indicated herein, it is meant to include any cited numeral (fractional or integral) within the indicated range. The phrases “ranging/ranges between” a first indicate number and a second indicate number and “ranging/ranges from” a first indicate number “to” a second indicate number are used herein interchangeably and are meant to include the first and second indicated numbers and all the fractional and integral numerals there between.

[00052] Whenever terms “plurality” and “a plurality” are used it is meant to include, for example, “multiple” or “two or more”. The terms “plurality” or “a plurality” may be used throughout the specification to describe two or more components, devices, elements, units, parameters, or the like. The term set when used herein may include one or more items. Unless explicitly stated, the method embodiments described herein are not constrained to a particular order or sequence. Additionally, some of the described method embodiments or elements thereof can occur or be performed simultaneously, at the same point in time, or concurrently.

[00053] As used herein the term "method" refers to manners, means, techniques and procedures for accomplishing a given task including, but not limited to, those manners, means, techniques and procedures either known to, or readily developed from known manners, means, techniques and procedures by practitioners of the chemical, biological, biochemical, and veterinary arts.

[00054] The term intensive culture , as used herein, means a standing biomass of exceeding 10kg/m³. The term “ standing biomass ”, as used herein, is defined as the total biomass of a given tank volume at a particular time.

[00055] The term "culture tank” refers to the collective system within a tank, including substrate stacks, tilt mechanisms, water ports associated with an external water treatment, air lift assembly, and various sensors and control systems. In contrast the term "tank" refers to the specific structure containing the liquid.

[00056] Turning now to the figures, FIG. 1 is a perspective, top-view of a culture tank 1 including a plurality of substrates 3 held as substrate stacks by a dedicated superframe or stack frame, also referred to as a substrate-stack frame 4. Substrates 3 are deployed in a substantially horizontal growth position and each of stack frames 4 are pivotally mounted to a frame mount 5 which in turn is secured to tank wall 2, as shown, or an alternative secure structure. The pivotal mount of stack frame 4 to frame mount 5 enables each substrate stack to be independently tilted into a harvest position ranging between 10° to 70 degrees from the horizontal. Tank 2 is constructed from concrete, metal or fiber- reinforced plastic in accordance with design considerations. Furthermore, it should be understood that tank 2 is implemented with a circular cross-section in a certain embodiment, whereas in a certain other embodiment it is implemented with any polygonal cross-section. In one example, tank 2 has a minimum diameter of two meters and a minimum depth of one meter.

[00057] FIG. 2 is a perspective top-view of a single substrate stack 3A of substrates in a substantially horizontal growth mode within stack frame 4. Substrates 3 are spaced between 5-20 cm in a certain embodiment and 7-10 cm in another embodiment; spacing dimensions for facilitating growth. The bottom substrate is also disposed at a height above the floor of 7-10 cm and the top substrate is submerged underneath the water surface also 7-10 cm. Such an arrangement provides a surface to volume ratio of at least 5m²/m³. As shown, substrates 3 are perforated with flow perforations or circulation slots 6 to facilitate fluid flow through substrates 3 as will be further discussed. The stacking of substrates 3 with adequate spacing between them enhances growth and yield of benthic invertebrates.

[00058] Substrate frame 4 is hingeably or pivotally mounted to frame mount 5 that is in turn mounted to lift mast 7 of a tilt mechanism, according to an embodiment. In other embodiments alternative structures providing support for frame mount 5 are employed. Substrate frame 4 includes a plurality of frame substrate holders 11 rotatably mounted to a frame backbone 4A. For the purposes of this document, the term frame refers to its backbone 4A and associated substrate holders 11. Tilt mechanism also includes lift arm or arm 8 and winch 7A, both mounted to mast 7, and a connection member 9 like a chain, cable, rope, chain or even a rod. For the purposes of this document and without diminishing in scope, connection member 9 will be discussed in terms of a cable. Tilt mechanism is operative to lift a distal end of stack frame 4 so that it pivots on frame support 5 when winch 7A winds cable 9. When stack frame 4 is tilted, all substrates 3 held by frame 4 through its substrate holders 11, assume a harvest or collection angle ranging between 10° to 70° relative the horizontal. The extent of tilt is configurable and includes 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, and 70° all relative to the horizontal, as noted.

[00059] While disposed in the growth position, the lower end of each substrate holder 11 are suspended above the tank floor. Holders 11 proximal to tank wall 2 are suspended above the tank floor to facilitate tilting during harvest, in this embodiment.

[00060] FIG. 3 is a perspective side-view depicting an enlarged cutaway view of substrate stack of substrates 3 mechanically linked to a stack frame 4 pivotally mounted to frame mount 5 in turn mounted to mast 7, according to an embodiment. As shown, uprights or frame substrate holders 11 are rotatably mounted to stack frame backbone 4A. Holders 11 traverse substrates 3 and holds them, as will be further addressed.

[00061] FIG. 4 is a schematic, bottom-view of a single substrate 3 and its substrate scaffold 12, according to an embodiment. As shown, substrate 3 has a surface geometry of a triangle with its vertices truncated, in a certain embodiment. The vertex truncation advantageously maximizes available surface area when multiple substrate stacks are deployed in a culture tank. This geometry facilitates placement of the substrate stacks along the circumference of a circular culture tank and prevents the substrates from contacting each other during titling into the harvest position.

[00062] Each substrate 3 is constructed from a polymeric material like high-density polyethylene (HDPE), polypropylene (PP), or polyvinyl chloride (PVC). Other polymeric materials and fiberglass that are stable in water and provide a rough surface can be utilized. Using the Verein Deutscher Ingenieure (VDI) standard for roughness, substrate roughness ranges between VDI 3400 Ref. 30 to VDI 3400 Ref. 36, in a certain embodiment.

[00063] During manufacture, substrates are constructed from half-units and assembled, in a certain embodiment.

[00064] As previously noted, substrates 3 are perforated with flow perforations 6 thereby enabling feed and waste to flow between substrates 3. Optionally, the ratio of open space of the perforations to surface area is up to 20%, in other words, the solid surface area of each substrate represents at least 80% of the total area of each substrate 3. In another example, the ratio of open space of the perforations to surface area is up to 10%, in other words, the solid surface area of each substrate represents at least 90% of the total area of each substrate 3. In a certain embodiment, flow perforations 6 are implemented as oval or rectangular slots having a width ranging between 8-10 mm and a length ranging between 20-125 mm. These flow perforations or slots provide sufficient area to enable the passage of feed while preventing organisms from falling through the slots.

[00065] As shown, each substrate is supported with a substrate scaffold 12 underneath substrate 3. Substrate scaffold 12 is a network of polymeric or fiberglass rods that also provides the connection means between substrates 3 and the stack frame 4 through substrate holders 11, according to an embodiment.

[00066] FIG. 5 is a perspective bottom-view depicting a mechanical linkage between substrate scaffold 12 and holders 11 of the stack frame 4, according to an embodiment. Each holder 11 has series of notches HA configured to receive substrate scaffold 12. Scaffold 12 rotates within notch 11A as holder 11 moves vertically while stack frame 4 is tilted into a harvest position and returned to a horizontal growth position. Horizontal growth positions can range between 0-10° from the horizontal, 2°, 4°, 6°, 8°, and 10°. Other connection configuration providing such functionality are included within the scope of this invention.

[00067] In operation, each winch 7A winds up its respective cable 9 thereby raising the distal end of substrate stack 3A and tilting substrates 3 as the association substrate scaffold 12 pivots within notches HA of substrate holders 11. Proximal holders 11 near the tank wall are suspended above the tank floor to enable tilting up to an angle up of 30° from the horizontal. As the angle of substrates 3 increases the benthic invertebrates slide down and off substrates 3. The proximal portion of substrates 3 is distanced from tank wall 2 about 10-20 cm, for example, to enable harvesting of the benthic invertebrates on the tank floor. Harvesting from the tank volume is implemented by pumping water together with the invertebrates from tank 2. The simultaneous rotation of substrate scaffold 12 of each substrate 3 within holders 11 ensures a constant distance between substrates 3 thereby ensuring that benthic invertebrates are not trapped in between adjacent substrates 3.

[00068] During cleaning and maintenance operations, stack frame 4 and associated substrates 3 are tilted to a near orthogonal position to provide uninhibited access to the tank 2. Unhindered tank access can also facilitate harvesting. During stocking culture tank 1, when the organisms are small, unneeded substrate stacks 3A are tilted into a near vertical position.

[00069] FIGS. 6-7 are perspective, side-views of two mechanically linked substrate stacks 3A and 3B in a harvest position within tank 2, according to an alternative embodiment. As shown in FIG. 6, rod 9A is pivotally mounted to distal end of a stack frame backbone 4A of first substrate stack 3A and a distal end of a second substrate stack 3B. As a distal end of stack frame backbone 4A of substrate stack 3A is raised, as described above, rod 9 also raises the distal end of stack frame backbone 4A of second substrate stack 3B when the proximal holders 11 of both stacks 3A and 3B remain suspended above the tank floor. FIG. 7 depicts an analogous arrangement except that the mechanical linkage between first substrate stack 3A and a second substrate stack 3B is implemented as a hinge set 14. As the distal end of stack frame backbone 4A of substrate stack 3A is raised, hinge set 14 pulls up the proximal end of stack frame backbone 4A of substrate stack 3B while the distal substrate holder 11 suspended above the tank floor. [00070] Drain 14 shown in FIG. 6 and drain column 15 shown in FIG. 7 are presented for context and will be further discussed.

[00071] FIGS. 8-9 are perspective, top-views of a culture tank employing one multistack frame 4B carrying all substrate stacks 3C, according to a second alternative embodiment. FIGS. 8-9 depict substrate stacks 3C in growth and harvest modes, respectively. As shown, substrates 19 are rectangular and are deployed in a rectangular tank 2A. Each stack 3C is held by a pair of non-sliding holders 11B rigidly mounted to frame 4B at point 17 and a pair of sliding holders 11C slidingly mounted in frame slots 16. Holders 11B and 11C are fitted with a series of engagement notches HA as described above in the context of FIG 5. Substrates 19 are also pivotally mounted in the engagement notches HA by way of scaffold 12 described above in the context of FIGS. 4-5. During harvest, multi-stack frame 4B is raised in its entirety as shown in FIG. 9. As holders 11B and 11C are lifted off the tank bottom, non-sliding holders 11B remain stationary whereas sliding holders 11C slide downward in frame slot 16 until stopper 18 abuts with frame 4B. Substrates 19 pivot into a tilting harvest position, as described above. Lifting is achieved by a crane or other heavy duty hoisting equipment. This is embodiment is well-suited for large-scale industrial cultivation. After harvesting and/ or maintenance activities, multistack frame 4A is lowered into tank 2A where substrates 19 assume a substantially horizontal growing position upon contact with the tank floor.

[00072] FIG. 10 is a perspective, side-view of a culture tank 2 with a water disperser or intake and output ports of water treatment system, according to an embodiment. As shown, the water treatment system includes a filtered drain column 15 and drain 14 in fluid communication with an external treatment facility (not shown) that treats the water to preserve or restore optimal growth conditions. The external treatment facility filters out particulates and dissolved waste products, oxygenates and heats the water if needed, and performs any other treatment operations in accordance with growth requirements. The treated water is then recycled to tank 2 through a series of ports 21 disposed along the length of pipes 20. Ports 21 are facing opposite directions on pipes 20 and 20A to advantageously creating multiple circulating currents around tank 2. The circulation currents ensure homogeneous optimal water conditions throughout tank 2. It should be appreciated that filtered drain column 15, in a certain embodiment, is fitted with exchangeable filters facilitating filtering with mesh size in accordance with the size of the organisms. Finer mesh filters are deployed when the organisms are smaller and are exchanged with larger mesh filters as the organisms grow. [00073] FIGS. 11-12 are perspective views of an air lift assembly depicting water and air intake ports, feed distribution ports, and a collection basket, according to an embodiment.

[00074] As shown, air lift assembly 22 includes water intake pipes 23 that converge into two distribution pipes 24 that feed into two collection baskets 26. In operation, compressed air is directed into intake pipes 23 though air ports 28. The compressed air advances through intake pipes 23 at a relatively high velocity and creates a low pressure zone that draws water and feed into intake pipes 23 through ports 27. The feed and water is then conveyed through intake pipes 23 into distribution pipes 24 where the feed falls through distribution ports 25 into as the water is drawn toward collection baskets 26 where the water and the compressed air is released. The re-suspended feed particles enable the benthic invertebrates to capture and consume those feed particles that would otherwise be wasted on the tank floor. In an alternative embodiment, separate airlifts are provided near a distal end of each substrate stack 3A.

[00075] Dead invertebrates are also drawn into intake pipes 23 and are generally too large to fall through distribution ports 25. The dead invertebrates are therefore conveyed to the collection basket 26 where they are filtered out of the water as it is released back into tank 2 above baskets 26. Ideally, air lift assembly 22 maintains a water velocity > 2 cm/sec, in a certain embodiment.

[00076] Air lift assembly 22 is operative to create vertical circulation providing homogenization of water conditions, re-suspension of feed particles and organic waste, prevention of feed waste; removal of dead benthic invertebrates, plus sampling opportunities of the benthic invertebrates.

[00077] The use of compressed air to convey water provides a number of advantageous over liquid pumps. Compressed air prevents impeller damage to the feed and to the live invertebrates. Additionally, within the operational conditions of the tank culture, airlift recycling is more economical and more maintenance free than a liquid pump.

[00078] FIG. 13 is a schematic depiction of a controller 30 managing the tilt mechanism, the water circulation system, and the air lift assembly, according to an embodiment. As shown, controller 30 includes a processor 31 in communication with, a user interface 33, a memory 33, sensors, network interface 35, sensors 36, a tilt motor 37, water circulation pump 38, air lift valves 39, and clock 40. User interface 33 includes input devices like mouse, touch screen, keyboard and output devices like screen monitor and printers, for example. Memory 34 includes both RAM and hard disc memory for data and algorithm storage as will be further discussed. Network interface 35 include both wireless and hardwire provisions. Sensors 36 includes underwater cameras and motion detectors. Lighting provisions are provided and managed in accordance with camera functionality. Both infrared and white light are provided.

[00079] Time activated imaging is provided and is configurable to activate imaging as a function of time provided by clock 40. Imaging provides user feedback in regard to feed supply, waste accumulation, turbidity, mortality, and growth status.

[00080] One or more tilt motors 37 are deployed to tilt each substrate stack 3A and are can be activated manually or automatically in response to a trigger event like time or invertebrate size. Tilt motors 37 are also configurable to tilt stacks 3A into a nearly vertical position to facilitate maintenance and also to return them to their substantially horizontal growth position. Furthermore, tilt motors 37 can be deactivated to enable manual tilting through a hand winch, for example. Water circulation pump 38 drives water circulation between tank 2 and an external treatment facility. Air lift valves 39 are operative to open ports 28 of FIGS 11-12. Ports 28 are in communication with compressed air such that valve control defines air lift functionality. Both circulation pump 38 and air lift valves 39 are configurable to operate on the basis of time and/or other trigger event s like pH, turbidity, oxygen content, or a combination of these items.

[00081] FIG. 14 is a sample flowchart 40 of processing steps employed in automated harvest, according to an embodiment. As shown, processing begins at step 41 and tracks time and date at step 42. An evaluation of the harvest time is performed at step 43 in accordance with configuration parameters. If the time to check growth has arrived, an image of shrimp, for example, is captured by an underwater camera in step 45. If the time has not arrived, processing continues at step 42. The image is analyzed in step 48 to ascertain if the shrimp has achieved a threshold length in accordance with system configuration parameters and dedicated algorithms. If a threshold length has not been achieved, processing returns to step 42. If the threshold size has been achieved processing continues to step 51 and a tilt motor 37 is activated to tilt a substrate stack 3A so that the shrimp will slide onto the tank floor for harvesting. In step 53, tilt motor 37 is activated in the opposite direction to restore substrate stack 3A back to the horizontal growth position at a predefined time, and processing terminates at step 55.

Claims

We claim:

1. A culture tank assembly for intensive culture of benthic invertebrates, the culture tank comprising: one or more submersible substrate stacks, each of the substrate stacks having a plurality of substantially horizontal substrates, each of the substrates disposed at an angle less than 10° from a horizontal plane; a substrate-stack frame, each of the substrates pivotally mounted to the frame; and a tilt mechanism configured to convey the substrate stack from the substantially horizontal position to a harvest position ranging between 30°-70° relative to the horizontal plane.

2. The assembly of claim 1, further comprising a frame mount, wherein the substratestack frame is pivotally mounted to the frame mount.

3. The assembly of claims 1 -2, wherein the tilt mechanism is operative to raise a distal end of the substrate-stack frame.

4. The assembly of any one of claims 1-3, wherein the assembly includes a substrate scaffold, wherein each of the substrates are mounted to a scaffold.

5. The assembly of any one of claims 1-4, wherein the substrate-stack frame includes a plurality of uprights, each of the uprights having a series of connection configurations, wherein each of the substrates scaffolds is pivotally mounted within the connection configurations. The assembly of claims 1, wherein the tilt mechanism is operative to raise proximal and distal ends of the substrate-stack frame. The assembly of claim 1, wherein the substrate -stack frames have a mechanical linkage linking a first substrate -stack frame to second substrate -stack frame. The assembly of claim 7, wherein the mechanical linkage is configured to raise a distal end of the second substrate-stack frame as a distal end of a first substratestack frame is raised. The assembly of claim 8, wherein the mechanical linkage is configured to raise a proximal end of the second substrate-stack frame as a distal end of a first substratestack frame is raised. The assembly of any one of claims 1-9, wherein the substrates have a plurality of circulation slots facilitating fluid flow when submerged in liquid. The assembly of claim 10, wherein the circulation slots have an oval geometry. The assembly of any one of claims 1-11, further comprising a controller configured to activate the tilt mechanism responsively to a trigger event. The assembly of claim 12, wherein the trigger event is a time or an invertebrate size. The assembly of any one of claims 1-13, further comprising an air lift assembly configured to direct compressed air into an intake pipe so as to create a suction drawing water into the intake pipe.

15. The assembly of any one of claims 1-14, further comprising filter intake column in fluid communication with two sets of vertically aligned inlet ports of a water treatment facility, the two sets of vertically aligned inlet ports operative to create a plurality of horizontal circulation currents within a tank of the culture tank assembly.

16. A method for harvesting cultured benthic invertebrates, the method comprising tilting a submerged stack of substrates holding cultured benthic invertebrates to an angle causing the benthic invertebrates to fall off the substrates.

17. The method of claim 16, wherein the tilting is responsive to a harvest time.

18. The method of claims 16-17, wherein the tilting is responsive to a threshold size of a benthic invertebrate.

19. The method of any one of claims 16-18, wherein the angle is 30° or less relative to a horizontal plane.

20. The method of any one of claims 16-19, further comprising returning the stack of substrates to a horizontal growth position.