SEAFARMING SYSTEM FOR AQUACULTURED ANIMALS

Abstract

Marine aquaculture animal rearing device, the device (1) comprising: at least one stack (30) of rearing enclosures (32) superimposed in a longitudinal direction, blades (34) connected to the rearing enclosures (32) and arranged such that the rearing enclosures (32) are driven in rotation about a longitudinal axis by the marine current, a structure (29) fixed to the seabed (8), a rotating linkage (56) connecting the stack or each stack (30) to the structure (29), having an element (57) enabling the stack or each stack (30) to rotate relative to the structure (29) about the longitudinal axis, characterized in that the stack or each stack (30) is suspended from the structure (29) by the rotating linkage (56), said rotating linkage (56) being arranged to enable the stack or each stack (30) to oscillate about a position in which the longitudinal direction is vertical.This rotation, combined with the tilt of the longitudinal axis produced by the current, causes the animals to roll against each other in the enclosures during periods of strong current.

Description

[0001] The invention relates generally to devices for raising aquaculture animals at sea, in particular shellfish and more particularly oysters.

[0002] In all oyster-farming countries, oysters are raised on supports or in fixed containers in the intertidal zone, and are subject to climatic, biological or chemical hazards that may affect farming performance.

[0003] About thirty years ago, the technique of offshore longline oyster farming emerged. In such farms, oysters are constantly submerged offshore and benefit from stable and healthy environmental conditions. They exhibit exceptional growth rates. For example, they are farmed in flexible Japanese lanterns, of the type described in patent application EP 0 682 863.

[0004] We also know from document FR2576484 of a device for raising molluscs comprising a mobile container permeable to water.

[0005] Another offshore farming technique developed over the last fifteen years involves raising oysters in containers arranged in steel cages.

[0006] Yet another offshore farming technique involves using rigid baskets, stacked on top of each other, forming a rigid lantern.

[0007] These last two techniques have three major drawbacks.

[0008] The first drawback is the bulkiness, since the volume of the containers / baskets is incompressible during transport, and represents ten times the volume of the farmed oysters.

[0009] The second problem is the fouling of the mesh used in the containers / baskets. The mesh must be cleaned very regularly, and even more frequently the smaller the mesh size. Small mesh sizes are used for raising small shellfish.

[0010] The third drawback is the weight of the containers / baskets. These must be highly rigid, as they are used in demanding environmental conditions.

[0011] Flexible Japanese lanterns, on the other hand, offer numerous advantages. They are compact when not in use. The nets are disposable, so there is no need to clean them, even when a small-mesh net is used for raising juveniles.

[0012] However, they provide an exceptionally high growth rate, especially for juveniles, so that the lanterns fill up very quickly and oysters on the same tray clump together rapidly. This leads to the need for very frequent intervention to split and separate the oysters, which is hardly compatible with mass production.

[0013] A state-of-the-art breeding device using Japanese lanterns is shown on the figure 1 This device includes a cable 2, also called a hawser, whose ends 4 and 6 are anchored to the seabed 8 by means of weights 10 and 12 connected by cables 14 and 16 to ends 4 and 6 respectively. Cables 14 and 16, for example, are approximately 30 meters long. The hawser 2 is approximately 100 meters long.

[0014] At regular intervals of about 6 m, as well as at the ends 4 and 6, buoys 18 are arranged connected to the hawser 2 by means of ropes 20. This allows the hawser to be kept at a depth of about 1 m and almost parallel to the seabed 8.

[0015] 22 Japanese lanterns are suspended under the hawsepipe, regularly spaced along it.

[0016] Each Japanese lantern 22 consists of a series of stacked trays 28 connected by ropes. The oysters 29 are placed on these trays. The tubular net 24 fits snugly around the edge of the trays to prevent the oysters from moving from one level to another. The whole structure forms a Japanese lantern 22 that extends almost vertically in the absence of a strong current, each lantern being connected at its base to a weight 26.

[0017] The effectiveness of Japanese lanterns for oyster growth relies on the use of ballast 26. This allows the lantern to remain vertical despite sea currents, so that seawater forcefully passes through the net and ensures excellent nourishment for the oysters located inside the Japanese lantern.

[0018] On the other hand, as mentioned above, we observe overgrowth of oysters raised under these conditions characterized by a high degree of shell fragility, as well as fouling of the interstitial media between the animals, on the trays, which can lead to over-mortality if maintenance and splitting interventions are not carried out at the right frequency, which is very high (around 15 days in summer), which is technically very difficult to achieve in the context of mass production.

[0019] In this context, the invention aims to provide a sea farming device that does not present the above disadvantages.

[0020] To this end, the invention relates to a device for raising aquaculture animals at sea according to claim 1.

[0021] The blades attached to the breeding enclosures cause these enclosures to be driven in rotation by the ocean current.

[0022] The blades notably allow the use of tidal power to rotate the breeding enclosures.

[0023] Indeed, marine aquaculture facilities are primarily located in relatively sheltered areas, such as straits, rias, or estuaries. They are therefore subject to tidal currents channeled by the river mouths. The strength of these currents fluctuates from zero to a maximum between high and low tide. Periods of tidal reversal, when the current is zero, occur at high and low tide. The strongest currents occur midway between high and low tide. During periods of strong current, typically for one-third of the time between high and low tide, the stack forms an angle with respect to the vertical. This tilt allows the blades to face the current and thus rotate the aquaculture pens. Furthermore, the aquaculture animals tend to congregate at the lowest points of the pens due to this tilt.And so, due to the rotation, the animals will be rolled against each other, like marbles in a cement mixer, throughout the period of strong current.

[0024] The rest of the time, the inclination of the rearing enclosures is too slight to cause movement of the aquaculture animals, allowing the animals to feed and develop their growth.

[0025] The rearing device may also exhibit one or more of the features of claims 2 to 15.

[0026] Other features and advantages of the invention will become apparent from the detailed description given below, by way of example and not limitation, with reference to the attached figures, including: there figure 1 is a schematic representation of a livestock farming system according to the state of the art; the figure 2 is a simplified schematic representation of part of a livestock farming device according to the invention, conforming to a first embodiment; the figure 3 is a view similar to that of the figure 2 showing the position of the stack of rearing enclosures during periods of strong current; the figure 4 is a perspective view of the tidal turbine equipping the stack of figures 2 et 3 ; there figure 5 is a simplified schematic representation of a method of attaching the tidal turbine to the lower platform of the device figures 2 et 3 ; there figure 6 is a side view of a stack of rearing enclosures for a second embodiment of the invention; the figure 7 is a representation of a variant of the second embodiment of the invention; the figures 8 et 9 These are schematic diagrams illustrating the arrangement of the blades on the rearing enclosures of the figure 6 ; there figure 10 illustrates an advantageous variant of the rearing device according to the second embodiment of the invention; the figure 11 is a view along the incidence of arrow XI of the figure 10 ; THE figures 12 et 13 schematically illustrate other types of structures fixed to the seabed and allowing the stacks of enclosures to be suspended.

[0027] The invention relates to a device for raising aquaculture animals at sea. These animals are typically shellfish, and more particularly oysters. Alternatively, the shellfish may be any kind of bivalve such as clams, mussels, or any other type of shellfish.

[0028] It is designed for farming at sea, i.e. in deep water. This farming can be carried out off the coast or in straits, estuaries or rias, or even in ponds connected to the sea, or in any other suitable location.

[0029] It is particularly suited to areas subject to tidal currents.

[0030] The rearing device 1 comprises a structure 29 fixed to the seabed.

[0031] Structure 29, for example, includes a cable 2 fixed to the seabed, for example as illustrated on the figure 1 and described above.

[0032] Alternatively, cable 2 is fixed to the seabed by any other suitable system.

[0033] The device also includes at least one stack 30 of rearing enclosures 32, superimposed one on top of the other in a longitudinal direction. In the representation of the figure 2 the longitudinal direction is vertical.

[0034] The device also includes blades 34 linked to the rearing enclosures 32 and arranged so that the rearing enclosures 32 are driven in rotation around a longitudinal axis by the marine current.

[0035] In the first embodiment, shown in the figures 2 à 5 The stacking of breeding enclosures is a flexible Japanese lantern.

[0036] It thus comprises a plurality of trays 36 stacked longitudinally one above the other. The trays 36 are threaded through a tubular net 38. The trays 36 define the rearing enclosures 32. The aquaculture animals 40 are placed on the trays, within each rearing enclosure 32. The tubular net 38 is tightened by any means against the edge of each tray 36 so as to confine the animals 40 inside each enclosure. Typically, each tray 36 is attached to longitudinally oriented ropes 42, designed to suspend the stack 30 from the cable 2.

[0037] According to the first embodiment, the device comprises for each stack 30 a hydro turbine 44 defining the blades 34.

[0038] Here, a hydro turbine is understood to be a hydraulic turbine that uses the kinetic energy of ocean currents and transforms it into a rotational movement of the breeding enclosures 32.

[0039] The hydro turbine can be of any suitable type.

[0040] For example, as illustrated on the figures 2, 3 And 4 The hydro turbine 44 comprises a hub 46, a rim 47 surrounding the hub 46, and blades 34 extending each from the hub 46 to the rim 47. The number, shape, and surface area of ​​the blades 34 are chosen to obtain sufficient rotational driving force under the operating conditions to be described later.

[0041] The tidal turbine 44 is typically linked to the rearing enclosure located at a lower longitudinal end of the stack 30.

[0042] In other words, the tidal turbine 44 is linked to the lowest plateau 36 in the stack.

[0043] In the example shown on the figures 2, 3 And 4 , the hydro turbine is linked to the said rearing enclosure by a ligature 48.

[0044] This means that these are cables which link the hydro turbine 44 to the lower rearing enclosure 32.

[0045] Advantageously, it is the lower ends of the ropes 42 that link the hydro turbine 44 to the lower rearing enclosure 32.

[0046] The ligature 48 links the hub 46 to the lower rearing enclosure.

[0047] In one embodiment shown on the figure 5 The hydro turbine 44 is linked to the lower rearing enclosure 32 by a rigid fixing 50. This rigid fixing is, for example, a clip.

[0048] For example, the plate 36 has an extension 52 fixed under this plate, which clips into the inside of the hub 46 of the hydro turbine.

[0049] The hydro turbine 44 is placed under the stack 30, along the longitudinal direction. In other words, it is placed longitudinally under the lower rearing enclosure 32.

[0050] The 44-meter hydro turbine is typically made of injection-molded plastic, for example, polypropylene. It can also have blades made of flexible materials, such as fabric like that used for sails or parachutes. These materials advantageously contain an additive to improve strength, UV resistance, or resistance to fouling (anti-fouling effect), for example.

[0051] Preferably, each stack 30 includes a ballast 54. The ballast 54 is, for example, mounted in the hub 46 of the hydro turbine. For example, the ballast 54 is a steel or lead ring, or a concrete block.

[0052] The device also includes a rotating link 56 from the stack 30 to the structure 29, here to the cable 2. The rotating link 56 includes a rotating element 57 which allows a rotation of the stack 30 relative to the structure 29 around the longitudinal axis.

[0053] The rotating link can be of any suitable type. For example, component 57 is a swivel or any other equivalent component allowing the rotation of the stack 30.

[0054] The link 56 is designed so that the stack 30 is suspended from the structure 29, and can swing around a position where the longitudinal axis is vertical, as shown in the figures 2 et 3 .

[0055] In the example shown on the figure 2 The link 56 includes a cable 58 itself fixed to the cable 2. The rotating member 57 links the cable 58 to the stack 30, preferably to the upper ends of the ropes 42.

[0056] As mentioned above, the rearing unit 1 is designed to be installed in an area subject to tidal currents. During tidal reversal periods, i.e., at high and low tide, the tidal currents are weak. The rearing enclosure stack 30 is therefore positioned with a nearly vertical longitudinal direction, as illustrated in the figure. figure 2 The axis of the hub 46, that is, the axis of the hydro turbine 44, is substantially vertical. In this position, the hydro turbine is not driven in rotation. The rearing enclosures are therefore substantially static. These conditions are favorable for the aquaculture animals 40 to feed and grow.

[0057] On the contrary, during the entire period of strong tidal current, the stack 30 is inclined, as illustrated on the figure 3 In other words, the longitudinal direction forms an angle α with the vertical. This angle α is a function of the strength of the tidal currents and the weight of the ballast 54. The tidal currents are represented by the arrows C on the figure 3 .

[0058] The ballast 54 is dimensioned so that the longitudinal direction forms an angle α with the vertical between 30° and 60° in the middle of a period separating high tide and low tide.

[0059] In other words, the angle α at the time when tidal currents are strongest is between 30° and 60°.

[0060] This angle depends on the strength of the current and therefore on the strength of the tide, and thus on the tidal coefficient, which varies daily between spring tides (high tides) and neap tides (low tides). The weight of the ballast 54 is chosen so that the angle α remains within the range indicated above, allowing rotation for a sufficient number of days between two neap tide periods to obtain the expected hardening results, depending on the type of farming (growing, fattening, etc.).

[0061] It should be noted that the presence of ballast is not mandatory. In some cases, the weight of the tidal turbine 44 and / or the assembly 30 of the rearing enclosures 32 or the animals 40 is sufficient to achieve the desired effect. The blades 34 are arranged so that, for a substantially horizontal ocean current, and for an angle α between 30° and 60°, the rearing enclosures 32 are driven in rotation around the longitudinal axis by the ocean current C.

[0062] In particular, the surface area and angle of incidence of the blades 34 are adjusted in relation to the marine current C.

[0063] In the example shown, the rearing enclosures 32 are linked in rotation to each other around the longitudinal axis. They are typically linked by the ropes 42.

[0064] The hydro turbine 44 drives the lower rearing enclosure 32 in rotation around its longitudinal axis. This, in turn, drives the enclosure immediately above it in rotation, and so on up to the enclosure 32 at the top of the stack 30. The rotating link 56 enables the rotation of the upper rearing enclosure 32 relative to the structure 29.

[0065] As seen on the figure 3 The rearing enclosures 32 are inclined with respect to the horizontal. In the example shown, the platforms 36 form an angle α with respect to the horizontal.

[0066] The aquaculture animals therefore gather at a low point in each rearing enclosure 32. Due to the rotation of the rearing enclosures, the farm animals continuously roll down towards the low point of the rotating platforms and are rolled over each other.

[0067] Typically, the blades 34 are arranged so that, given the strength of the sea currents in the area where the farming device is located, such a rotational movement occurs for at least 25 to 50% of the time between high tide and low tide, ideally for one third of said time.

[0068] During the rest of the time, the inclination, i.e. the angle a, is too small to cause movement of the aquaculture animals.

[0069] Such movement promotes self-cleaning of the rearing enclosures 32. It also promotes abrasion of the shells of aquaculture animals, preventing overgrowth and sticking together by nacre of the animals with each other or on the rearing enclosures.

[0070] This also promotes the fattening of animals, since the feed effort is not exclusively diverted towards shell growth but is also devoted to the accumulation of reserves.

[0071] Typically, the sea-farming device 1 comprises a plurality of stacks 30, each linked to the structure 29 by a rotating link 56. Each stack is identical to that described above and is equipped with its own tidal turbine 44. When the structure 29 has a cable 2, the stacks 30 are fixed side by side, regularly spaced along the cable 2, as illustrated in the figure 1 .

[0072] A second embodiment of the invention will now be described, with reference to figures 6 à 11 .

[0073] Only the points by which the second embodiment differs from the first will be detailed below. Identical elements or elements performing the same function will be designated by the same reference numerals.

[0074] In the second embodiment, the rearing enclosures are rigid cages. The stack 30 does not constitute a flexible Japanese lantern, but a rigid one. Each cage has one or more walls made of mesh, with the aquaculture animals arranged inside the basket. The baskets 32 are rigidly fixed to one another.

[0075] This arrangement is illustrated on the figure 9 , which shows a side view of lockers 32.

[0076] In the second embodiment, the blades 34 are rigidly fixed to the breeding enclosures 32 and are distributed longitudinally along the stack 30.

[0077] More specifically, the blades 34 advantageously form at least one longitudinally oriented helix. The helix winds around the stack 30 as illustrated in the figure 6 .

[0078] Typically, a given rearing enclosure 32 carries at least one of the blades 34. As illustrated on the figures 8 et 9 , the blades carried by the enclosure immediately above and by the enclosure immediately below in the stack 30 can be placed in line with each other.

[0079] For example, each blade 34 extends over one-eighth of a turn, so that the blades carried by eight consecutive enclosures in the stack make it possible to constitute a continuous propeller turn of a given pitch.

[0080] Preferably, between four and ten speakers are needed to complete one step, i.e., one turn of the helix.

[0081] Advantageously, the 34 blades form a simple helix. Such a helix is ​​illustrated on the figure 6 In this case, each enclosure carries a single blade 34.

[0082] In an alternative embodiment illustrated on the figure 7 The blades 34 form a double helix. A double helix has two helical threads, parallel to each other. In this case, each enclosure 32 carries two blades 34, typically diametrically opposed.

[0083] In the second embodiment of the invention, each rearing enclosure 32 typically has a circular section perpendicular to the longitudinal direction.

[0084] In the second embodiment, each stack 30 includes a ballast 54 as described in relation to the first embodiment of the invention.

[0085] In the second embodiment, the ocean current drives the stack 30 by acting on the helical helix.

[0086] It should be noted that the helix does not necessarily extend over the entire height of the stack. Thus, some rearing enclosures 30 may not be equipped with blades 34. The helix may be discontinuous and consist of two sections separated by a space not equipped with blades.

[0087] Typically the 34 blades can be removable, allowing the number and size of the 34 blades to be adapted to the circumstances or desired effects.

[0088] Each breeding enclosure 30 thus includes at least one zone 59 arranged for the removable attachment of one of the blades 34. The zone 59 is arranged for example to clip the blade 34. By varying, the zone 59 allows attachment by screwing or by any other means.

[0089] For example, the 59 attachment zones waiting on the lockers are multiple and thus allow one or more helices to be formed.

[0090] The fixing areas 59 advantageously allow the removable blades to be installed in the direction of direct or indirect rotation, thus allowing the same rack to be used to form lanterns with direct or indirect helical rotation.

[0091] The length and width of the propeller are chosen according to the desired driving force.

[0092] As described above, the device 1 typically comprises several stacks 30 linked side by side to the structure 29. The spacing separating the stacks 30 along the structure 29 is generally less than the height of each stack 30. During the highest tides, each stack risks coming into contact with neighboring stacks.

[0093] To avoid friction between the stacks, the respective blades of two neighboring stacks 30 are arranged so that said two neighboring stacks 30 are driven in rotation relative to structure 2 in opposite directions of rotation. This is illustrated in the figures 10 et 11 . Thus, in the event of contact during very high tides for example, the stacks 30 roll against each other, like a gear.

[0094] Alternatively, the stack of 30 rearing enclosures made up of rigid compartments may not be equipped with blades forming a helical propeller, but may be equipped with a hydro turbine of the type described in relation to the first embodiment of the invention.

[0095] Conversely, the stack 30 of the flexible Japanese lantern type may not be equipped with a hydro turbine but rather with blades attached to each rearing enclosure and together defining a helix with a longitudinal axis, as in the second embodiment of the invention. In this case, the blades 34 are advantageously rigidly fixed to the platform 36, and the platforms 36 are fixed against rotation relative to each other.

[0096] Structure 29 may not include a cable 2 of the type described above.

[0097] Alternatively, the structure 29 fixed to the seabed includes a raft 60 of the type illustrated on the figure 12 The raft floats on the surface of the water and is fixed to the seabed 8 for example by means of weights 10, 12 and cables 14, 16. One or more stacks 30 are suspended from the raft 60.

[0098] According to another variant, the structure 29 comprises a platform 62 rigidly fixed to the seabed 8. The platform 62 is fixed by rigid posts 64. One or more stacks 30 are suspended from the platform 62.

[0099] The present invention eliminates overgrowth while allowing for uniform shellfish growth. The abrasion caused by movement results in shellfish with a perfect shape and hard shells. The self-cleaning process, along with the slowed growth, significantly limits the action of pathogens and the consequences of post-mortem degradation. In edible-sized animals, it also promotes a high fattening rate, resulting not only in excellent shape and shell quality, but also in a meat content that places these products in the premium category (highest meat indices on the market).

Claims

1. A device for rearing aquaculture animals at sea, the device (1) comprising: - at least one stack (30) of rearing enclosures (32), superimposed on top of each other in a longitudinal direction, - blades (34) linked to the rearing enclosures (32) and arranged such that the rearing enclosures (32) are rotated around a longitudinal axis by the sea current, - a structure (29) fixed to the seabed (8), - a rotary connection (56) of the or each stack (30) to the structure (29), having a member (57) authorizing a rotation of the or each stack (30) relative to the structure (29) around the longitudinal axis, wherein the or each stack (30) is suspended from the structure (29) by the rotary link (56), said rotary link (56) being arranged to allow the or each stack (30) to swing around a position where the longitudinal direction is vertical.

2. The device according to claim 1, characterized in that the device (1) includes a marine turbine (44) defining said blades (34).

3. The device according to claim 2, characterized in that the marine turbine (44) is connected to the rearing enclosure (32) located at a lower longitudinal end of the stack (30).

4. The device according to claim 3, characterized in that the marine turbine (44) is connected to the rearing enclosure (32) located at a lower longitudinal end of the stack (30) by a binding (48) or a rigid fastener (50).

5. The device according to any one of claims 2 to 4, characterized in that the marine turbine (44) is made from a plastic containing an additive provided to improve the solidity, or UV resistance, or resistance to soiling.

6. The device according to claim 1, characterized in that the blades (34) are rigidly attached to the rearing enclosures (32) and are longitudinally distributed along the stack (30).

7. The device according to claim 6, characterized in that the blades (34) together form at least one propeller with a longitudinal axis.

8. The device according to any one of the preceding claims, characterized in that the or each stack (30) includes a plurality of plates (36) superimposed longitudinally and slipped into a tubular net (38), the plates (36) defining the rearing enclosures (32).

9. The device according to any one of claims 1 to 7, characterized in that the rearing enclosures (32) are rigid basket traps.

10. The device according to any one of the preceding claims, characterized in that the or each stack (30) includes a ballast (54).

11. The device according to claim 10, characterized in that the ballast (54) is dimensioned so that the longitudinal direction forms, with the vertical, an angle (α) comprised between 30° and 60° at the middle of a period separating the high tide and low tide.

12. The device according to any one of the preceding claims, characterized in that the structure (29) includes a cable (2), or a raft (60), or a platform (62) rigidly fixed to the seabed (8), the or each stack (30) being connected to said cable (2) or said raft (60) or said platform (62).

13. The device according to any one of the preceding claims, characterized in that the device (1) comprises several stacks (30) connected side by side to the structure (29), the respective blades (54) of two adjacent stacks (30) being arranged so that said two adjacent stacks (30) are rotated relative to the structure (29) along respective rotation directions opposite one another.

14. The device according to any one of the preceding claims, characterized in that the or each rearing enclosure (32) comprises at least one removable fastening zone (59) for one of the blades (34).

15. The device according to claim 14, characterized in that the fastening zone (59) is arranged to selectively allow the installation of the blade (34) for the rotation in the direct direction or for the rotation in the indirect direction of the rearing enclosure (32).