GB2547417B

GB2547417B - Fish tank and method

Info

Publication number: GB2547417B
Application number: GB1602503.3A
Authority: GB
Inventors: Eikelid Tomas
Original assignee: Sogn Ind As
Current assignee: Sogn Ind As
Priority date: 2016-02-11
Filing date: 2016-02-11
Publication date: 2019-10-16
Anticipated expiration: 2036-02-11
Also published as: NO344854B1; NO20170218A1; GB201602503D0; GB2547417A

Description

FISH TANK AND METHOD

TECHNICAL FIELD

The present disclosure relates to fish tanks, for example the present disclosurerelates to fish tanks for use with off-shore renewable energy systems, forexample wave energy systems. Moreover, the present disclosure concernsmethods of operating the aforementioned fish tanks. Furthermore, the presentdisclosure relates to methods of harvesting fish from the aforementioned fishtanks.

BACKGROUND

Fish tanks for aquaculture are well known, for example fish tanks employingperipheral nets or meshes suspended in water from one or more peripheralbuoyancy members. Such fish tanks are employed for salmon fish aquaculturein Norway and Scotland.

In a published Norwegian patent application N0910404A (Applicant: BetongAS), there is described a floating reinforced concrete fish tank for aquaculture.The fish tank includes at least one buoyancy member. Moreover, the fish tankhas a peripheral wall that is implemented as a double wall defining a volumethat is not in fluidic communication with a central region of the fish tank, whereinthe central region is employed in operation for aquaculture, namely providing aliving space for various types offish.

In a granted Norwegian patent NO153031B (Applicant: Ewos AB), there isdescribed an aquatic enclosure for fish aquaculture, wherein the aquaticenclosure includes a container with a water inlet and a water outlet. Theaquatic enclosure for fish aquaculture is optionally manufactured from fibreglassreinforced concrete.

In a granted Norwegian patent NO158401B (Applicant: Einar Knutsen), there isdescribed an arrangement for providing a fish tank construction. Thearrangement includes a stiff construction component that is operable to providea platform, that is manufactured from concrete and that is operable to float on ornear an ocean surface. The arrangement is provided with several baffles todefine respective fish tanks. There is thereby provided a robust fish tankconstruction that is simple and robust, and is capable of withstandingchallenging ocean weather conditions. The arrangement is capable of beingraised and lowered in an ocean by water and air ballast, as required.

In a published Japanese patent application JP H11131510A (Applicant:Mitsubishi Heavy Industries Ltd.), there is described an apparatus that isoperable to float in an ocean environment. The apparatus employs light-gradeconcrete in an upper portion of the apparatus, and is provided with ballast tanksthat are used in operation to vary a depth of the apparatus in water when inoperation.

In a published PCT patent application WO 96/08143 A1 (Applicant: R.Engelsen), there is described a fish tank that is constructed from concrete.Moreover, from a published Norwegian patent application NO20111326A(Applicant: Agrimarine Industries Inc.), and also from published Norwegianpatents NO175341B (Applicant: Geir Kjersem, et al.) and NO332341B1(Applicant: Ecomerden AS), it is known to fetch water from depths under anenclosed fish tank and to circulate the fetched water within the enclosed fishtank.

In a published US patent application US20100224136 A1 (Applicant: Ernest D.Papadoyianis et al.), there is described a floating fish production system forplacement within a body of water and being structured and disposed forcontaining fish and other aquatic animal, plant and algal species; the systemincludes at least one primary containment tank having an arrangement ofindividual solid wall sections and an arrangement of individual solid floor sections. Flexible membranes span between and connect to adjacentlypositioned solid wall and floor sections to define flexible connecting joints thatallow the individual solid wall and floor sections to move relative to one anotherin an articulating action. The flexible membranes allow the tank configuration todeform temporarily from a relaxed state in response to externally applied forcesexerted on the tank (for example, waves, wind, current) to thereby absorb theexternally applied forces and reduce stress on the structural integrity on thetank. An air lift system including a high volume, low pressure blower and aspaced arrangement of vertically extending air lift pipes delivers water andoxygen from the exterior body of water and into the tank interior. A flexible maindrain in a central area at the bottom of the tank connects to a waste recoverysystem for removing waste produced by the fish and other aquatic species.

In another published US patent application US2011308473A1 (Applicant:Richard Buchanan), there is described a system for cultivating marine specieswhich employs a marine-based array of floating closed-containment tankscomposed of panels made of waterproof fiberglass laminate materials andinternal buoyant foam-based materials. The panels, connected by flangedstruts, form the walls and bottom of the tanks, which are substantially cylindricalin overall shape. The tops of the tanks are open to the atmosphere but areprotected from predators via a thick mesh top net. The system also employs afiltration system which utilizes centrifugal water flow and hydraulics to removesludge and solid matter which is then filtered and transformed into a componentfor use in garden fertilizers. It also uses an electronic computerized system formonitoring and controlling the marine species rearing environment.

In a granted US patent US5092268A (Applicant: Vanus L. Taylor), there isdescribed a habitat for raising aquatic life such as fish, wherein there ismonitored a temperature and a dissolved oxygen content of water in the habitat,and wherein there is introduced water from an epilimnion to increase thedissolved oxygen content and the temperature. The habitat is air powered by alow pressure air source which releases air into the habitat to move water during a cyclic operation of a ram-like member. In an alternative implementation, thereis drawn cool water from the hypolimnion to mix with warm oxygen-ladenepilimnion water; a yet further implementation is powered by wave action in anopen sea region surrounding the habitat.

In a published FR patent application FR2687286A1 (Applicant: Belbati Abel),there is described an off-shore fish farming structure with a useful volume of700 m3 and its immersion/emersion device. The immersion/emersion deviceconsists of a floatation system (namely, an assembly of tubular modules linkedtogether by flanges) secured to an assembly, and to two ascending parachutes.After adjusting volumes of air in the ascending parachutes (by use of a set ofvalves), and in the compartments of the flotation system (namely, a confined-aircompartment with constant volume), it suffices to operate the single valveintegral with the buoy of a narghile in order for emersion to take place (byinjection of air with the aid of a compressor or diving bottles) or immersion (byopening the valve, the air then evacuating the ballasts). A rigid "skeleton", and awidth of the space formed over the periphery of the usable volume (namely, anet with fish) makes it possible to stretch an anti-diver protection "net" and toprotect livestock from risks of squashing due to folding of the net during strongsubmarine currents or violent storms which strike the assembly at unprotecteddepths.

In a published EP application EP0076151A2 (Applicant: Masao Saito et al.),there is described an apparatus for a fish breeding tank which includes a frame,a netted body held by the frame to form a space for receiving fish to be bred,and a plurality of air floats attached to the tank and arranged to be suppliedthrough air supply pipes with air for adjusting a buoyancy of the tank in water,the apparatus comprising control means adapted to operate, when the fishbreeding tank is tilted more than a predetermined angle, to decrease orincrease buoyancy of the associated air float for restoring the fish breeding tankto its normal position.

Although fish tanks manufactured from concrete are already known, they havenot achieved widespread use for aquaculture, for various technical andeconomic reasons. There therefore arises a need to provide more advancedtypes offish tanks manufactured from concrete, that are more suitable for use incombination with off-shore renewable energy systems, for example waveenergy systems. Moreover, there also arises a need for such types offish tanksthat are less prone to harbouring various types of parasites, for example salmonlice.

SUMMARY

The present disclosure seeks to provide a fish tank for aquaculture.

Moreover, the present invention seeks to provide a method of operating a fishtank. A further aim of the present disclosure is to at least partially overcome at leastsome of the problems of the prior art, as discussed above.

In a first aspect, embodiments of the present disclosure provide a fish tank foraquaculture, characterized in that the fish tank is fabricated at least in part inconcrete, wherein the fish tank includes: (i) a peripheral side wall and a base portion coupled to the peripheral sidewall, wherein the peripheral side wall and the base portion define aregion in which aquaculture occurs in operation, wherein the baseportion is conical, wherein the peripheral side wall and/or the baseportion are armoured with steel towards inner parts by way of steel-reinforced concrete and with fiberglass towards outer parts by way offibreglass-reinforced concrete; (ii) a support structure for providing support to the peripheral side walland/or the base portion, wherein the support structure is fabricated fromreinforced concrete; (iii) a ballast-adjusting arrangement for raising and/or lowering the fish tankwithin a surrounding aquatic environment; (iv) an instrumentation arrangement for monitoring the region within the fishtank in which aquaculture occurs in operation, wherein theinstrumentation arrangement includes at least one sensor operable tomonitor fish environment and fish condition in the region in which theaquaculture occurs in operation; (v) a circulating arrangement for circulating and/or aerating water within thefish tank, wherein the circulating arrangement includes at least one re-circulating pump; and (vi) a draining arrangement for draining the fish tank when its fish are to beharvested, wherein the draining arrangement is disposed at a centralposition ofthe base portion.

The invention is of advantage in that the fish tank is a relatively large structurethat is more stable in an ocean environment, has better operational efficiency, iseasier to upgrade due to its modular construction, uses materials moreefficiently, is more robust, and is easier for harvesting of fish, as compared toconventional fish tanks.

Optionally, the base portion is conical in form, and has the drainingarrangement disposed at a central position therein.

Optionally, the peripheral side wall is inwardly tapered or outwardly tapered, asa function of its height.

Optionally, the peripheral side wall is any one of: circular in form, polygonal inform, rectilinear in form, triangular in form, elliptical in form.

Optionally, the peripheral side wall is implemented as an upper side wall portionand a lower side wall portion, wherein the upper side wall portion is configured to house the instrumentation arrangement, and the lower side wall portion isconfigured to house the ballast-adjusting arrangement.

More optionally, the support structure is disposed internally within the peripheralside wall and/or the base portion at least in part.

Optionally, the fish tank has dimensions that substantially lie within a range ofwavelengths of waves encountered in its surrounding aquatic environment, forexample having principal dimensions in a range of 5 metres to 50 metres.

Optionally, the fish tank includes a water-tight cover, coupled to the peripheralside wall, which enables the fish tank to be completely submerged within itssurrounding aquatic environment. Submerging the fish tank enables the fishtank to be better protected in severe weather conditions, because ocean waveshave a wave energy field whose intensity decreases exponentially as a functionof depth into the ocean and also as a function of wave wavelength.

Optionally, the ballast-adjusting arrangement includes a plurality of ballast tanksthat are individually adjustable in buoyancy in operation, for adjusting a tiltand/or a height of the fish tank within its surrounding aquatic environment.

Optionally, the fish tank includes a filtering arrangement for filtering outmetabolic waste products and/or uneaten food from the fish tank.

The instrumentation arrangement includes a configuration of sensors that areoperable to monitor fish environment and fish condition in the region in whichaquaculture occurs in operation. In this regard, the configuration of sensorsincludes at least one of: video cameras, infrared cameras, biosensors, gassensors, water-conductivity meters, salt-water chemical analysis sensors,pathogen-monitoring sensors, water-flow monitoring sensors, temperaturesensors, liquid-level detectors.

In a second aspect, embodiments of the present disclosure provide a method ofoperating a fish tank, characterized in that the method includes: (i) arranging for the fish tank to include a peripheral side wall and a baseportion coupled to the peripheral side wall, wherein the peripheral sidewall and the base portion define a region in which aquaculture occurs inoperation, and arranging for the fish tank to include a support structurefor providing support to the peripheral side wall and/or the base portion,wherein the support structure is fabricated from reinforced concrete,wherein the peripheral side wall and/or the base portion are armouredwith steel towards inner parts by way of steel-reinforced concrete andwith fiberglass towards outer parts by way of fibreglass-reinforcedconcrete; (ii) using a ballast-adjusting arrangement of the fish tank to raise and/orlower the fish tank within a surrounding aquatic environment; (iii) using an instrumentation arrangement of the fish tank to monitor aregion within the fish tank in which aquaculture occurs in operation,wherein the instrumentation arrangement includes at least one sensoroperable to monitor fish environment and fish condition in the region inwhich aquaculture occurs in operation; (iv) using a circulating arrangement of the fish tank to circulate and/oraerate water within the fish tank, wherein the circulating arrangementincludes at least one re-circulating pump; and (v) using a draining arrangement of the fish tank to drain the fish tankwhen its fish are to be harvested, wherein the draining arrangement isdisposed at a central position of the base portion.

Optionally, the method includes using a filtering arrangement of the fish tank tofilter out metabolic waste products and/or uneaten food from the fish tank.

Optionally, the method includes using a configuration of sensors of theinstrumentation arrangement to monitor fish environment and fish condition inthe region in which aquaculture occurs in operation.

Optionally, the method includes using the ballast-adjusting arrangement tocompletely submerge the fish tank within its surrounding aquatic environment.

Optionally, the method includes individually adjusting a plurality of ballast tanksof the ballast-adjusting arrangement in buoyancy to adjust a tilt and/or a heightofthe fish tank within its surrounding aquatic environment.

In a third aspect, embodiments of the present disclosure provide a method ofharvesting fish from a fish tank pursuant to the aforementioned first aspect,characterized in that the method includes: (i) using a draining arrangement of the fish tank to drain the fish tank whenits fish are to be harvested; (ii) mooring an aquatic vessel in a proximity of the fish tank; and (iii) collecting the fish in the moored aquatic vessel.

Optionally, the method includes using a circulating arrangement of the fish tankto aerate remaining water within the fish tank.

Additional aspects, advantages, features and objects of the present disclosurewould be made apparent from the drawings and the detailed description of theillustrative embodiments construed in conjunction with the appended claims thatfollow.

It will be appreciated that features of the present disclosure are susceptible tobeing combined in various combinations without departing from the scope ofthepresent disclosure as defined by the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The summary above, as well as the following detailed description of illustrativeembodiments, is better understood when read in conjunction with the appendeddrawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, thepresent disclosure is not limited to specific methods and apparatus disclosedherein. Moreover, those in the art will understand that the drawings are not toscale. Wherever possible, like elements have been indicated by identicalnumbers.

Embodiments of the present disclosure will now be described, by way ofexample only, with reference to the following diagrams wherein: FIG. 1 is an illustration of basic portions of a fish tank of an AquaCycleapparatus, pursuant to embodiments of the present disclosure; FIGs. 2A-C are more detailed illustrations of component parts of the fish tankof FIG. 1, illustrating a support structure of the fish tank forproviding increased structural robustness; FIG. 3 is an illustration of water circulation occurring in operation withinthe fish tank of FIG. 1; FIG. 4 is a cross-sectional illustration of the component parts of the fishtank of FIG. 1; FIG. 5 is a schematic illustration of a conventional fish tank foraquaculture; and FIG. 6 is a schematic illustration of practical dimensions of an internalregion of the fish tank of FIG. 1.

In the accompanying diagrams, an underlined number is employed to representan item over which the underlined number is positioned or an item to which theunderlined number is adjacent. A non-underlined number relates to an itemidentified by a line linking the non-underlined number to the item. When anumber is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow ispointing.

DETAILED DESCRIPTION OF EMBODIMENTS

The following detailed description illustrates embodiments of the presentdisclosure and ways in which they can be implemented. Although some modesof carrying out the present disclosure have been disclosed, those skilled in theart would recognize that other embodiments for carrying out or practising thepresent disclosure are also possible.

In overview, the present disclosure concerns an apparatus for aquaculture,namely a fish tank for aquaculture. The apparatus includes a peripheral sidewall, a base portion, and a support structure that provides support to the sidewall and/or the base portion.

The apparatus pursuant to embodiments of the present disclosure isconveniently referred to as being AquaCycle apparatus, namely a type of fishtank; “AquaCycle” is a trademark. The AquaCycle apparatus is a water-tightand self-floating fish tank that is fabricated at least in part in concrete.Optionally, the AquaCycle apparatus is fabricated in a manner that itsdimensions substantially lie within a range of wavelengths of wavesencountered in its surrounding aquatic environment, more optionally in oceanenvironments; for example, principal ocean waves, for example “rollers”, usuallyhave a wavelength in a range of circa 5 metres to 100 metres, so theAquaCycle apparatus advantageously has a diameter in an order of 60 metres.This potentially provides the AquaCycle apparatus with a long operating lifetimewhen deployed in ocean environments. Moreover, the AquaCycle apparatus isdesigned to be adapted to various use scenarios, as will be described in greaterdetail below.

It will be appreciated that concrete is a material that is frequently used in marineenvironments, and is capable of providing a long lifetime of use in various typesof challenging weather conditions; marine-grade concrete has substantiallyclosed pores, and is capable of surviving decades of exposure to ocean saline conditions. Indeed, there are contemporarily found floating constructions fromthe Second World War that are still in operation. Moreover, concrete isemployed for lower frameworks of contemporary floating oil and gas platform foroff-shore use.

In a first aspect, embodiments of the present disclosure provide a fish tank foraquaculture, characterized in that the fish tank is fabricated at least in part inconcrete, wherein the fish tank includes: (i) a ballast-adjusting arrangement for raising and/or lowering the fish tankwithin a surrounding aquatic environment; (ii) an instrumentation arrangement for monitoring a region within the fishtank in which aquaculture occurs in operation; (iii) a circulating arrangement for circulating and/or aerating water within thefish tank; and (iv) a draining arrangement for draining the fish tank when its fish are to beharvested.

According to an embodiment of the present disclosure, the fish tank includes aperipheral side wall and a base portion coupled to the peripheral side wall,wherein the peripheral side wall and the base portion define the region in whichaquaculture occurs in operation.

According to an embodiment of the present disclosure, the base portion isconical in form, and has the draining arrangement disposed at a central positiontherein. The draining arrangement is implemented by way of an inlet and outlethole at a centre of the base portion.

According to an embodiment of the present disclosure, the peripheral side wallhas a substantially vertical orientation when in use. Optionally, in this regard,principal inside and outside surfaces of the peripheral side wall have asubstantially vertical orientation when in use.

According to another embodiment of the present disclosure, the peripheral sidewall is inwardly tapered or outwardly tapered, as a function of its height. Suchtapering is optionally at a wall angle in a range of 0° to 20° from a verticaldirection when in use; more optionally, in a range of 0° to 10° from the verticaldirection.

Moreover, the peripheral side wall can be fabricated in any suitable form. Theperipheral side wall can be any one of: circular in form, polygonal in form,rectilinear in form, triangular in form, elliptical in form.

According to an embodiment of the present disclosure, the peripheral side wallis implemented as an upper side wall portion and a lower side wall portion,wherein the upper side wall portion is configured to house the instrumentationarrangement, and the lower side wall portion is configured to house the ballast-adjusting arrangement.

Optionally, in this regard, the upper side wall portion is usefully implemented asan instrument room for housing instruments for monitoring fish environment andfish condition within the fish tank. Optionally, the upper side wall portion is inoperation maintained above a water surface level of the surrounding aquaticenvironment, thereby isolating the instrument room from a temperature of thesurrounding aquatic environment. Moreover, this makes it possible to regulatethe temperature in the region in which aquaculture occurs to a certain extent,without dissipating a large amount of energy into the surrounding aquaticenvironment.

Optionally, the peripheral side wall includes an intermediate side wall portionbetween the upper side wall portion and the lower side wall portion. Optionally,the intermediate side wall portion provides for storage of isopor or other similarmaterial, which can be used to ensure buoyancy even if there is a leak from thefish tank to the surrounding aquatic environment; “Isopor3’ is a trademark.

Optionally, the lower side wall portion is usefully employed as a ballast spacefor housing one or more ballast tanks of the ballast-adjusting arrangement.Optionally, the one or more ballast tanks are at least partially filled with water tolower the fish tank within its surrounding aquatic environment. Moreover, a gas,for example air, is used to at least partially fill the one or more ballast tanks toraise the fish tank within its surrounding aquatic environment. It will beappreciated that the fish tank is suitable for use in ocean environments, as wellas inland and estuary waters.

Additionally, optionally, the lower side wall portion is usefully employed forhousing equipment required for filtering, circulating and/or processing waterwithin the fish tank, namely in the region where fishes are nurtured.

Moreover, according to an embodiment of the present disclosure, the fish tankincludes a support structure for providing support to the peripheral side walland/or the base portion.

Optionally, the support structure is disposed internally within the peripheral sidewall and/or the base portion at least in part. More optionally, the supportstructure is disposed internally between inside and outside surfaces of theperipheral side wall and/or the base portion. An example of such a supportstructure has been provided in conjunction with FIGs. 2A-C.

Optionally, the support structure is operable to be load-bearing. Optionally, inthis regard, the support structure is fabricated from reinforced concrete. Moreoptionally, the support structure is fabricated from one or more of: concrete,metals, metal alloys, composites, fibreglass.

According to an embodiment of the present disclosure, the fish tank isfabricated from at least one of: composites, fibreglass, glass, metals, metalalloys, plastics materials.

Optionally, the fish tank is constructed as a unitary structure. Alternatively,optionally, the fish tank is constructed from a plurality of component parts thatare mutually coupled together, for example bolted and/or clamped together.

Optionally, the fish tank is constructed in such a manner that there is an outerwall with a bearing structure included within an interior volume defined by theouter wall, thereby enabling the fish tank to be unaffected by exteriormovements of ocean water surrounding the fish tank and movement of fishincluded within the fish tank. Such a manner of construction enables othertypes of materials to be employed for portions of the fish tank, for exampleglass, fibreglass, composites, plastics materials and so forth.

The peripheral side wall and/or the base portion are armoured with steeltowards inner load-bearing parts thereof, for example, by way of steel-reinforced concrete. The peripheral side wall and/or the base portion arearmoured with fibreglass towards outer parts thereof, for example, by way offibreglass-reinforced concrete, to provide an effective barrier against sea water.In such cases, the peripheral side wall and/or the base portion are the primaryload-bearing structures of the fish tank, and render the fish tank robust againstforces encountered in an ocean environment.

Beneficially, the fish tank is a water-tight structure that is capable of providingan effective barrier to migration of fish. This potentially prevents certainenvironment risks that contemporary aquaculture pose to their surroundingaquatic environments, for example, such as escape of non-native speciesand/or genetically modified species into the surrounding aquatic environments,which may potentially compete with native species for food and habitat.

Moreover, optionally, the fish tank is built to a physical size, as will elucidated ingreater detail below, that enables the fish tank to sustain waves encountered inocean environments. Optionally, the fish tank has dimensions that substantiallylie within a range of wavelengths of waves encountered in its surrounding aquatic environment. More optionally, the fish tank has dimensions thatsubstantially lie within a range of ten’s of metres.

Moreover, according to an embodiment of the present disclosure, the fish tankhas an open top, and is implemented as a self-floating structure. Optionally, inthis regard, the fish tank includes barriers to prevent fish escaping from the fishtank; optionally, the barriers are implemented as a grid or grill to reduce theirweight and promote water flow within the fish tank.

According to another embodiment of the present disclosure, the fish tankincludes a water-tight cover, coupled to the peripheral side wall, which enablesthe fish tank to be completely submerged within its surrounding aquaticenvironment. This is particularly beneficial during extremely severe weatherconditions, for example, when wave energy of waves increases to such anextent that is potentially damaging to the fish tank and/or its operation. Whenthe fish tank is submerged in water within its surrounding aquatic environment,the wave energy experienced by the fish tank is decreased as an exponentialfunction of wavelength of the waves. Optionally, the fish tank is capable ofbeing submerged to a depth whereat the wave energy is reduced by at least70%, and more optionally, by at least 90%.

The fish is capable of being raised and lowered within its surrounding aquaticenvironment and/or being submerged to a desired depth, by employing theballast-adjusting arrangement in operation, to provide the fish tank with effectiveprotection in various weather conditions.

According to an embodiment of the present disclosure, the ballast-adjustingarrangement includes a single ballast tank. Optionally, the ballast tank isattached at a bottom portion of the fish tank similar to a manner in which aballast tank is mounted within a boat.

According to another embodiment of the present disclosure, the ballast-adjusting arrangement includes a plurality of ballast tanks that are individuallyadjustable in buoyancy in operation, for adjusting a tilt and/or a height of the fishtank within its surrounding aquatic environment. More optionally, the ballast-adjusting arrangement includes at least three ballast tanks. Optionally, waterand gas content of the ballast tanks is individually adjusted, so that an overall tiltof the fish tank within its surrounding aquatic environment can be adjusted.

Furthermore, it will be appreciated that fish waste, arising from fish metabolicprocesses, is a major problem in contemporary aquaculture. In contemporaryin-ocean aquaculture, fish waste collects on the ocean bottom, therebydamaging or completely eliminating bottom-dwelling life; moreover, fish wastecan also decrease dissolved oxygen levels in the water column, thereby puttingfurther pressure on native species in the surrounding aquatic environment.

Optionally, in this regard, the fish tank includes a filtering arrangement forfiltering out metabolic waste products and/or uneaten food from the fish tank.The filtering arrangement is optionally implemented by way of pumps and filters.

Optionally, metabolic waste products and/or uneaten food are collected, dried,and then used as a form of bio-fuel for generating energy, for example foroperating the pumps associated with the fish tank. Optionally, the metabolicwaste products and/or uneaten food are bio-fermented to provide methane orsimilar flammable gases that are capable of powering an internal combustionengine. Optionally, the internal combustion engine has an output shaft that iscoupled directly to the pumps, or via an electrical generator to provide electricalpower that mechanically drives the pumps.

Moreover, it will be appreciated that one of the greatest challenges incontemporary aquaculture is salmon lice and fish sicknesses, for example whena high spatial concentration of fish shoals occurs. In order to control both aquantity and a quality of fish in the fish tank, the fish tank employs the instrumentation arrangement in combination with the circulation arrangementand the filtering arrangement to both monitor and process water within the fishtank.

When implementing aquaculture in conventional fish tanks, there are manyoperating parameters that are often not known in practice and are difficult tomonitor. As a result, there is often a lack of information regarding a biologicalstatus of fish in such conventional fish tanks, when implementing aquaculture.The fish tank pursuant to embodiments of the present disclosure is capable ofproviding effective monitoring offish environment and fish condition.

According to an embodiment of the present disclosure, the instrumentationarrangement includes a configuration of sensors that are operable to monitorfish environment and fish condition in the region in which aquaculture occurs inoperation. Optionally, in this regard, the configuration of sensors is operable tomeasure an average size and/or weight of fish, thereby enabling better controloffish nutrition utilized, for example, thereby enabling the fish to be cultivated toan ideal slaughter weight and providing a simpler aquaculture process ingeneral.

According to an embodiment of the present disclosure, the configuration ofsensors includes at least one of: video cameras, infrared cameras, biosensors,gas sensors, water-conductivity meters, salt-water chemical analysis sensors,pathogen-monitoring sensors, water-flow monitoring sensors, temperaturesensors, liquid-level detectors.

As an example, measurements from the pathogen-monitoring sensors can beused to monitor fish health, and determine whether or not medicine drugs arerequired to be used for disease control; optionally, the pathogen-monitoringsensors are operable to detect metabolic bio-products generated by pathogens,for example by using protein binding molecules coupled to fluorophores that canbe detected using optical sensors when exposed to exciting radiation, for example ultra-violet radiation. As another example, measurements from thewater-conductivity meters and/or the salt-water chemical analysis sensorsand/or oxygen sensors can be used to determine whether or not fresh seawater is required to be provided to the region in which aquaculture occurs inoperation. As yet another example, measurements from the temperaturesensors can be used to regulate temperature within the region in whichaquaculture occurs in operation. As still another example, measurements fromthe liquid-level detectors can be used to detect a leakage from the fish tank in aquick and effective manner. Such liquid-level detectors typically detectpressure differences between one or more portions of the fish tank and asource of water. Optionally, changes in ballast can be used to address, forexample to compensate for, such leakage.

In a second aspect, embodiments ofthe present disclosure provide a method ofoperating a fish tank, characterized in that the method includes: (i) using a ballast-adjusting arrangement of the fish tank to raise and/orlower the fish tank within a surrounding aquatic environment; (ii) using an instrumentation arrangement ofthe fish tank to monitor a regionwithin the fish tank in which aquaculture occurs in operation; (iii) using a circulating arrangement of the fish tank to circulate and/or aeratewater within the fish tank; and (iv) using a draining arrangement of the fish tank to drain the fish tank whenits fish are to be harvested.

According to an embodiment of the present disclosure, the method includesusing a filtering arrangement of the fish tank to filter out metabolic wasteproducts and/or uneaten food from the fish tank.

According to an embodiment of the present disclosure, the method includesusing a configuration of sensors of the instrumentation arrangement to monitorfish environment and fish condition in the region in which aquaculture occurs inoperation.

According to an embodiment of the present disclosure, the method includesusing the ballast-adjusting arrangement to completely submerge the fish tankwithin its surrounding aquatic environment.

According to an embodiment of the present disclosure, the method includesindividually adjusting a plurality of ballast tanks of the ballast-adjustingarrangement in buoyancy to adjust a tilt and/or a height of the fish tank within itssurrounding aquatic environment.

According to an embodiment of the present disclosure, the method includesusing a circulating arrangement of the fish tank to aerate remaining water withinthe fish tank. Oxygen is beneficially supplied, for example via bubbleoxygenation, to the remaining water within the fish tank, so that the fish do notin any way suffer from a lack of ventilation. Careful handling of the fish isdesirable so that the harvested fish are of best quality and provided without fishsuffering occurring, namely to address an issue of animal welfare and to avoidunnecessary trauma or stress inflicted to the fish.

As the water from the fish tank is removed, a ballast-adjusting arrangement ofthe fish tank is used to adjust a height of the fish tank, for example in acompensating manner, so that the fish tank does not rise excessively above thewater surface in its surrounding aquatic environment.

Optionally, a grid or grill is used to collect the fish and lift them onto the mooredaquatic vessel.

Alternatively, optionally, the collection of the fish is facilitated by providing awater passage via a pipe coupled between the aquatic vessel and theremaining water in the fish tank, such that the fish swim via the water passageto the aquatic vessel. The water passage can, for example, be provided by wayof a flexible spiral-reinforced large diameter hose or similar.

Next, embodiments of the present disclosure will be described with reference tofigures.

Referring to FIG. 1 and 2A, there is shown a basic form of a fish tank foraquaculture pursuant to embodiments of the present disclosure. The fish tankis indicated generally by 10 and includes a peripheral side wall 20 whoseprincipal inside and outside surfaces have a substantially vertical orientationwhen in use, and a conical base portion 30 whose centre is at a greatest depthwhen the fish tank 10 is deployed in an aquatic environment and whose outerperipheral edge is coupled to the aforesaid peripheral side wall 20. The centreof the conical base portion 30 is provided with an inlet and outlet hole 40.

Water from the fish tank 10 can be drained through the hole 40 when the fishtank 10 is raised within its surrounding aquatic environment for preparing thefish for eventual harvesting.

Although the peripheral side wall 20 is shown in the diagrams associated withthe present disclosure to have a circular form, it will be appreciated that theperipheral side wall 20 can alternatively have another geometric form, forexample elliptical, polygonal, rectilinear, triangular, hexagonal, and so forth.

In FIGs. 2A, 2B and 2C, there is shown a support structure 50 for providingsupport to the peripheral side wall 20 and the base portion 30, wherein the support structure 50 is operable to be load-bearing. The support structure 50beneficially employs strengthening tubes or columns of concrete and/or steel.

In FIG. 2B, the support structure 50 is shown without the side wall 20 and thebase portion 30 being shown. The support structure 50 includes a plurality ofbarriers 50A, 50B, and optionally, a base portion 55. Optionally, the barriers50A, 50B are vertically-tapered in a manner that substantially complements theconical form of the base portion 30. The barriers 50A, 50B are substantiallyvertically orientated, when the fish tank 10 is deployed in use.

Optionally, the barriers 50A include vertical projections at their peripheral edgesto provide mechanical support to the peripheral side wall 20.

Optionally, the fish tank 10 includes a plurality of ballast tanks that are mountedin regions between vertical projections of adjacent barriers 50A. In such acase, the vertical projections of the barriers 50A act as physical barriers whenthe ballast tanks become separated.

With reference to FIG. 2C, the vertical projections of the barriers 50A extendupwardly within the fish tank 10 from a lower side wall portion 20B to an upperside wall portion 20A of the side wall 20. These vertical projections increasethe strength ofthe upper side wall portion 20A ofthe side wall 20.

In the fish tank 10, there are optionally employed inner columns that arearmoured with steel, wherein the inner columns are not directly exposed to seawater.

Optionally, the base portion 30 and/or the base portion 55 are armoured withsteel towards inner load-bearing parts thereof, and are armoured with fibreglasstowards outer parts thereof to provide an effective barrier against sea water.The base portion 30 and the base portion 55 are the primary load-bearing structures of the fish tank 10, and render the fish tank 10 robust against forcesencountered in an ocean environment. FIGs. 1 and 2A-C are merely examples, which should not unduly limit the scopeof the claims herein. A person skilled in the art will recognize many variations,alternatives, and modifications of embodiments of the present disclosure.

There will next be described water circulation within the fish tank 10, withreference to FIG. 3. In order to promote circulation within the fish tank 10 whenin operation so as to provide the fish in the fish tank 10 with a more naturalsimulation of the surrounding aquatic environment, there are beneficiallyemployed a plurality of, for example four, injection tubes 70 that spray jets ofwater into the fish tank 10, to promote a general circulation denoted by an arrow60 in FIG. 3. The injection tubes 70, for example, have a diameter of circa 1metre, and provide injection of a large volume of water at a low pressure. Thispotentially enables re-circulating pumps of a circulating arrangement of the fishtank 10 that are operable to generate the circulation 60 to have a long operatinglifetime and provide a high energy operating efficiency. Moreover, generatingthe circulation 60 in such a manner results in less acoustic noise beinggenerated, that is less disturbing to the fish in the fish tank 10, therebypromoting better fish growth, as disturbed fish tend to be agitated and therebyreduce their body mass in unnecessary swimming motion within the fish tank10.

Optionally, the pumps for generating the circulation 60 are housed in the lowerside wall portion 20B and/or are mounted sub-sea, for example on an undersideof the fish tank 10. Optionally, the pumps for creating the circulation 60 areincluded within the injection tubes 70, for example in-line axial multi-stageturbine-pumps.

Referring next to FIG. 4, the fish tank 10 advantageously has dimensions inexample ranges of dimensions D1 to D6 as provided in Table 1:

Table 1: Example dimensions for the fish tank 10

As per the illustrated practical example, the fish tank 10 has an inner volume ofapproximately 30 000 m3, for providing a region for fish aquaculture. Optionally,the fish tank 10 has an inner volume in a range of 10 000 m3 to 50 000 m3,more optionally in a range of 20 000 m3 to 40 000 m3. However, it will beappreciated that the fish tank 10 is optionally built to be larger than the exampleranges provided in Table 1 above, to achieve yet greater stability in oceanenvironments.

Referring next to FIGs. 5 and 6, there are shown example dimensions for thefish tank 10 in FIG. 6, in comparison to a conventional contemporary fish tank inFIG. 5. In FIG. 6, only an internal region of the fish tank 10 in whichaquaculture occurs in operation is shown for comparison of volume and size.

The conventional fish tank, likewise the fish tank 10, is constructed from circa3135 m3 of concrete, and has a weight of 7546 tonnes. With steel armouring,the weight is circa 8151 tonnes. However, in the case of the fish tank 10 in FIG.6, its weight is distributed over a larger area of the ocean surface, therebyimproving its floating stability. Beneficially, the fish tank 10 is constructed so

that it is somewhat deeper and broader in comparison to the contemporary fishtank; such a construction improves an operating robustness ofthe fish tank 10.

Moreover, the relatively flatter construction of the fish tank 10 in comparison tothe fish tank illustrated in FIG. 5, is that the fish tank 10 is relatively easier tokeep clean, for example when scrubbing its internal walls prior to providing thefish tank 10 with a new shoal offish.

In conclusion, the AquaCycle apparatus provides a platform in a form ofthe fishtank 10 that is modular in concept, rendering it easy to modify and adapt infuture. From having characterized materials used in construction of the fishtank 10, it is estimated that it would be able to provide more than 50 years ofoperating lifetime within a corrosive saline ocean environment. Moreover, itsmanner of construction allows for inspection and repair, for example to increaseits useable lifetime yet further.

By year 2016, considering costs for materials and labour, the fish tank 10 isestimated to cost in a range of NOK 15 million to NOK 20 million to construct.However, in view of degradation of ocean environments in general, for examplein the Pacific Ocean due to the Fukushima Dai’ichi accident in year 2011causing constant leakage of dangerous radioisotopes into the Pacific Ocean(Iodine 134, Cesium 137, Strontium 90, Tritium, Plutonium 239) potentially forcenturies, the price of safe radiation-contamination-free fish is likely to riseconsiderably in future, making the fish tank 10 a valuable investment with arelatively short investment amortization period on account of its characteristic ofbeing able to support a healthy environment within it for high-quality healthy fishaquaculture.

The fish tank 10 is capable of being fabricated in calm water, for example inharbours, fjords or river estuaries, and then being towed to a location in anocean environment whereat it is to be deployed. Arrays of the fish tanks 10 areof such a size that they are capable of absorbing wave energy, thereby synergistically functioning as off-shore wave calming devices, for example forreducing a rate of coastal erosion. Moreover, the fish tank 10 is beneficiallydeployed in a wake of an off-shore wave energy system, for example deployedin combination with an off-shore wind park.

Modifications to embodiments of the invention described in the foregoing arepossible without departing from the scope of the invention as defined by theaccompanying claims. Expressions such as “including”, “comprising”,“incorporating”, “consisting of’, “have”, “is” used to describe and claim thepresent invention are intended to be construed in a non-exclusive manner,namely allowing for items, components or elements not explicitly described alsoto be present. Reference to the singular is also to be construed to relate to theplural. Numerals included within parentheses in the accompanying claims areintended to assist understanding of the claims and should not be construed inany way to limit subject matter claimed by these claims.

Claims

CLAIMS We claim:

1. A fish tank (10) for aquaculture, characterized in that the fish tank (10) isfabricated at least in part in concrete, wherein the fish tank (10) includes: (i) a peripheral side wall (20) and a base portion (30) coupled to theperipheral side wall (20), wherein the peripheral side wall (20) and thebase portion (30) define a region in which aquaculture occurs inoperation, wherein the base portion (30) is conical, wherein theperipheral side wall (20) and/or the base portion (30) are armoured withsteel towards inner parts by way of steel-reinforced concrete and withfiberglass towards outer parts by way of fibreglass-reinforced concrete; (ii) a support structure (50) for providing support to the peripheral side wall(20) and/or the base portion (30), wherein the support structure (50) isfabricated from reinforced concrete; (iii) a ballast-adjusting arrangement for raising and/or lowering the fish tank(10) within a surrounding aquatic environment; (iv) an instrumentation arrangement for monitoring the region within the fishtank (10) in which aquaculture occurs in operation, wherein theinstrumentation arrangement includes at least one sensor operable tomonitor fish environment and fish condition in the region in which theaquaculture occurs in operation; (v) a circulating arrangement for circulating and/or aerating water within thefish tank (10), wherein the circulating arrangement includes at least onere-circulating pump; and (vi) a draining arrangement (40) for draining the fish tank (10) when its fishare to be harvested, wherein the draining arrangement (40) is disposedat a central position ofthe base portion (30).

2. A fish tank (10) of claim 1, characterized in that the base portion (30) isconical in form, and has the draining arrangement (40) disposed at a centralposition therein.

3. A fish tank (10) of claim 1 or 2, characterized in that the peripheral sidewall (20) is inwardly tapered or outwardly tapered, as a function of its height.

4. A fish tank (10) of claim 1, 2 or 3, characterized in that the peripheral sidewall (20) is any one of: circular in form, polygonal in form, rectilinear in form,triangular in form, elliptical in form.

5. A fish tank (10) of any one of claims 2 to 4, characterized in that theperipheral side wall (20) is implemented as an upper side wall portion (20A) anda lower side wall portion (20B), wherein the upper side wall portion (20A) isconfigured to house the instrumentation arrangement, and the lower side wallportion (20B) is configured to house the ballast-adjusting arrangement.

6. A fish tank (10) of claim 5, characterized in that the support structure (50)is disposed internally within the peripheral side wall (20) and/or the base portion(30) at least in part.

7. A fish tank (10) of any one of claims 2 to 6, characterized in that the fishtank (10) includes a water-tight cover, coupled to the peripheral side wall (20),which enables the fish tank (10) to be completely submerged within itssurrounding aquatic environment.

8. A fish tank (10) of any one of the preceding claims, characterized in thatthe fish tank (10) has dimensions that substantially lie within a range ofwavelengths of waves encountered in its surrounding aquatic environment.

9. A fish tank (10) of any one of the preceding claims, characterized in thatthe ballast-adjusting arrangement includes a plurality of ballast tanks that areindividually adjustable in buoyancy in operation, for adjusting a tilt and/or aheight of the fish tank (10) within its surrounding aquatic environment.

10. A fish tank (10) of any one of the preceding claims, characterized in thatthe fish tank (10) includes a filtering arrangement for filtering out metabolicwaste products and/or uneaten food from the fish tank (10).

11. A fish tank (10) of any one of the preceding claims, characterized in thatthe instrumentation arrangement includes a configuration of sensors that areoperable to monitor fish environment and fish condition in the region in whichaquaculture occurs in operation.

12. A fish tank (10) of claim 11, characterized in that the configuration ofsensors includes at least one of: video cameras, infrared cameras, biosensors,gas sensors, water-conductivity meters, salt-water chemical analysis sensors,pathogen-monitoring sensors, water-flow monitoring sensors, temperaturesensors, liquid-level detectors.

13. A method of operating a fish tank (10), characterized in that the methodincludes: (i) arranging for the fish tank (10) to include a peripheral side wall (20) anda base portion (30) coupled to the peripheral side wall (20), wherein theperipheral side wall (20) and the base portion (30) define a region inwhich aquaculture occurs in operation, and arranging for the fish tank(10) to include a support structure (50) for providing support to theperipheral side wall (20) and/or the base portion (30) , wherein thesupport structure (50) is fabricated from reinforced concrete, whereinthe peripheral side wall (20) and/or the base portion (30) are armouredwith steel towards inner parts by way of steel-reinforced concrete andwith fiberglass towards outer parts by way of fibreglass-reinforcedconcrete; (ii) using a ballast-adjusting arrangement of the fish tank (10) to raiseand/or lower the fish tank (10) within a surrounding aquaticenvironment; (iii) using an instrumentation arrangement of the fish tank (10) to monitor aregion within the fish tank (10) in which aquaculture occurs in operation,wherein the instrumentation arrangement includes at least one sensor operable to monitor fish environment and fish condition in the region inwhich aquaculture occurs in operation; (iv) using a circulating arrangement of the fish tank (10) to circulate and/oraerate water within the fish tank (10), wherein the circulatingarrangement includes at least one re-circulating pump; and (v) using a draining arrangement (40) of the fish tank (10) to drain the fishtank (10) when its fish are to be harvested, wherein the drainingarrangement (40) is disposed at a central position of the base portion(30).

14. A method of claim 13, characterized in that the method includes using afiltering arrangement of the fish tank (10) to filter out metabolic waste productsand/or uneaten food from the fish tank (10).

15. A method of claim 13 or 14, characterized in that the method includesusing a configuration of sensors of the instrumentation arrangement to monitorfish environment and fish condition in the region in which aquaculture occurs inoperation.

16. A method of claim 13, 14 or 15, characterized in that the method includesusing the ballast-adjusting arrangement to completely submerge the fish tank (10) within its surrounding aquatic environment.

17. A method of claim 13, 14, 15 or 16, characterized in that the methodincludes individually adjusting a plurality of ballast tanks of the ballast-adjustingarrangement in buoyancy to adjust a tilt and/or a height of the fish tank (10)within its surrounding aquatic environment.

18. A method of harvesting fish from a fish tank (10) of any one of claims 1 to12, characterized in that the method includes: (i) using a draining arrangement (40) of the fish tank (10) to drain the fishtank (10) when its fish are to be harvested; (11) mooring an aquatic vessel in a proximity of the fish tank (10); and (iii) collecting the fish in the moored aquatic vessel.

19. A method of claim 18, characterized in that the method includes using acirculating arrangement of the fish tank (10) to aerate remaining water within thefish tank (10).