CAGE TO PROTECT SHELLFISH FROM PREDATORS

Description

DOMAINE DE L'INVENTION

[0001] The invention is in the field of shellfish cultivation, and more particularly mussel farming.

[0002] The present invention relates to a cage for protecting against shellfish predators, configured to be placed on a support for farming shellfish, in particular mussels. ETAT DE LA TECHNIQUE

[0003] Attacks by predators, such as ducks, gulls, sea bream and other fish, have become a very common problem on mussel farms, whether these mussels are raised on suspended ropes, longlines or on stakes, known as "bouchots".

[0004] This situation jeopardizes an entire industry, since the economic losses can be very significant. For example, a school of adult sea bream can devour up to 160 tons of mussels in a few minutes.

[0005] As can be seen on the figure 1 attached, to carry out the cultivation of mussels on a pile, a pile A is planted vertically or approximately vertically on the seabed B and a rope C, on which the mussel spat D (i.e. the juveniles) has developed, is wound in a spiral around the pile. This rope C is then fixed at its two ends, on the upper part of the pile and on the lower part of the latter, at a certain distance from the bottom B.

[0006] In this type of breeding, a flexible net E in the shape of a sock is currently used as a means of protection against predators. It is threaded around the stake and the spat coil and is pressed against the mussels, following the shape of the coil.

[0007] In addition, to protect the mussels from crab attacks, a device F, known as a "Tahitian", is placed around the base of pile A, at the level of the space existing between the bottom B and the lower end of rope C. This device F consists of a strip of flexible plastic material, cut so as to form a fringe at its lower part. Its purpose is to prevent the progression of crabs along pile A. Flexible nets F are unfortunately fragile and therefore not very durable. They can break and are therefore a source of pollution for the marine environment. They must be renewed regularly, for example annually, which is expensive. They require a lot of labor to install and must be cleaned regularly to remain effective.

[0008] Finally, depending on the sea currents, these E nets can even move and no longer play their protective role against predators.

[0009] Also known from document FR 2 589 323 is a device for obtaining shellfish spat, such as oysters, which comprises a tubular mesh sleeve that can be folded accordion-style around a central support. However, such a device does not include a net closing cover provided with deformable tabs.

[0010] Finally, document CA 2 504 390 discloses a device for producing molluscs and crustaceans, which comprises a plurality of superimposed lattice trays, but which does not include a net closing cover provided with deformable tabs. EXPOSE DE L'INVENTION

[0011] The invention therefore aims to solve the aforementioned problems and in particular to propose a protection device which is effective against predators, solid, shock-resistant and which is simple and quick to install and remove.

[0012] To this end, the invention relates to a cage for protecting against shellfish predators, configured to be placed on a shellfish farming support, such as a stake, a rope or a line, these shellfish being in particular mussels.

[0013] According to the invention, this cage comprises: an elongated, hollow body with a lattice structure delimiting openings, such as meshes, the dimensions of which are configured to prevent the predatory action of said predators, this hollow body being open at its two opposite ends, called respectively the lower end and the upper end, and two devices for closing the hollow body, one of the two closing devices being fixed to the lower end of the body and the other device to the upper end of the body, each closing device being configured to at least partially close the end of the hollow body while having an opening allowing the passage of said breeding support through this closing device and being configured to allow the centering of the hollow body relative to this breeding support and the maintenance of this centering, at least one of these closing devices comprising a cover provided with cutouts which extend radially from its center, so as to form a plurality of deformable tabs, these tabs being able to deform to allow the passage of the breeding support and to be able to press against it over at least part of their length, in order to ensure the centering of the hollow body relative to said breeding support and the maintenance of this centering, said hollow body and the two closing devices being made of semi-rigid plastic material.

[0014] Thanks to these characteristics of the invention, the cage made of semi-rigid material and whose mesh prevents predators from accessing it is kept in position relative to the breeding stake.

[0015] It is easy to install and remove since it simply slides vertically relative to the pile by passing the pile through the openings provided in each closing device.

[0016] According to other advantageous and non-limiting characteristics of the invention, taken alone or in combination: the cover comprises a plate provided on its periphery with a plurality of orifices allowing the passage of ties for fixing said cover on the lower end and / or the upper end of the body; the upper end and / or the lower end of the hollow body is provided or are provided with cutouts forming flaps and in that said closing device is formed of these flaps which are folded towards the inside of the body and held in the folded position by ties, the flaps being sized and configured so that once folded, they form between them an opening which allows the passage of said breeding support and that their free ends are in contact with this breeding support, in order to ensure the centering of the hollow body relative to said breeding support; the hollow body is of square cross-section and has four side walls; each side wall has a width of between 35 cm and 45 cm, preferably equal to 40 cm;the meshes of the body are diamond-shaped or square-shaped, one of the diagonals of which has a length of between 14 mm and 40 mm and the other diagonal of which has a length of between 14 mm and 40 mm; the cage is provided with at least one gripping handle; the semi-rigid plastic material is a shape memory material; the semi-rigid plastic material is high-density polyethylene. DESCRIPTION DES FIGURES

[0017] Other characteristics, aims and advantages of the invention will emerge from the following description, which is purely illustrative and non-limiting, and which must be read in conjunction with the appended drawings in which: [ Fig. 1 ] is a diagram representing a device for protecting mussels cultivated on stakes (bouchot) against predators, according to the state of the art. [ Fig. 2 ] is an exploded view of the protective cage according to a first embodiment of the invention. [ Fig. 3 ] is a top view of the cage of the figure 2 . [ Fig. 4 ] is a schematic view of a possible embodiment of a mesh of the body of the protective cage. [ Fig. 5 ] is a perspective view of the cage cover according to the first embodiment of the invention of the figure 2 . [ Fig. 6 ] is a perspective and top view of part of the cage of the figure 2 . [ Fig. 7 ] is a perspective view of the protective cage according to a second embodiment of the invention. DESCRIPTION DETAILLEE DE L'INVENTION

[0018] The protective cage 1 according to the invention is intended to be installed on a support for farming shellfish, in particular mussels. This farming support is referenced A. This farming support is for example a pile as shown in the figure 1 and in the remainder of the description, it will be described as such. Such a stake or "bouchot" generally has a diameter of between 10 cm and 20 cm, preferably 15 cm. However, this breeding support could also be a rope or line, which is either suspended vertically or arranged horizontally or substantially horizontally between two posts. For example, such ropes or lines have a diameter of the order of 30 mm to 40 mm.

[0019] A first embodiment of the invention will now be described with reference to the figures 2 And 3 .

[0020] The protective cage 1 according to the invention comprises a body 2 and two closing devices 3 for this body 2.

[0021] Body 2 is a hollow and elongated sleeve, with a longitudinal axis X-X'. It is formed of a lattice structure delimiting openings 20. This openwork structure thus allows the passage of water flows, loaded with nutrients, towards the shellfish raised on pile A.

[0022] Body 2 is made of semi-rigid plastic, as will be described later.

[0023] The openings 20 are preferably meshes.

[0024] These 20 meshes are sized to prevent predators from preying on the shellfish, including ducks, gulls, sea bream, and other fish. "Prevent predators from preying" means being able to prevent them from accessing the shellfish, particularly by passing their heads, beaks, or mouths through the mesh.

[0025] The 20 meshes can for example be square or diamond shaped. For information purposes, and as shown in the figure 4 , one of the diagonals D1 of the mesh has a length of between 14 mm and 40 mm, preferably between 20 mm and 30 mm, more preferably of the order of 25 mm and the other diagonal D2 has a length of between 14 mm and 40 mm, preferably between 20 mm and 30 mm, more preferably of the order of 25 mm. If the mesh is square, the two diagonals are of the same lengths.

[0026] As it appears better on the figure 3 , this body 2 is open at its two ends. The body 2 has an upper end 21 and an opposite lower end 22, the terms "upper" and "lower" being to be taken into consideration in relation to the normal position of use of the cage, which is that shown in the figure 2 .

[0027] Preferably, the body 2 has a square cross-section with four side walls 23. This shape makes it possible to limit the deformation of the body in the event of impact, for example by a boat.

[0028] Other shapes are possible. Body 2 could thus have a circular section.

[0029] The closing device 3 is a cover intended to cover the two ends 21, 22 of the body 2.

[0030] The cover 3 has a shape corresponding to that of the cross-section of the body 2, in order to be able to close the end of the body 2 on which it is placed. In the exemplary embodiment shown in the figures 2 And 4 , this cover 3 is square.

[0031] This cover 3 has a square plate 31, bordered by a peripheral rim 32.

[0032] Furthermore, the plate 31 is provided with a plurality of through-orifices 33, advantageously arranged all around its periphery, these orifices 33 allowing the introduction of links 34 for fixing the cover 3 to the ends 21, 22 of the body 2. These links 34 pass for example through the meshes 20, (see figure 6 ).

[0033] Furthermore, as can be seen on the figure 5 , this cover 3 (in particular the plate 31) is provided with a plurality of cutouts 35 which extend radially from its center. These cutouts 35, preferably rectilinear, thus delimit between them tabs 36. In addition, advantageously, the cover 3 can have a central opening 37 of small dimensions at the point of intersection of the different cutouts 35.

[0034] When the cover 3 is fixed to the end of the body 2, the plate 31 extends perpendicularly or substantially perpendicularly to the side walls 23 and its center is located on the axis X-X'.

[0035] The cover 3 is also made of semi-rigid plastic material. The combination of the use of this material with the shape of the cutouts 35 makes the tabs 36 deformable while retaining a certain rigidity.

[0036] There figure 6 illustrates the protective cage 1 when it is inserted onto the pile A by sliding vertically from top to bottom. The tabs 36 bend and move outwards due to the presence of the pile A and remain pressed over at least part of their length against the circumference of the latter. By moving apart, these tabs 36 delimit an opening 5 for the passage of the pile A.

[0037] This cover 3 therefore allows both: to close the end of the body 2 by the plate 31, to allow the passage of the pile A through the opening 5, and to center the hollow body 2 in relation to this pile A using the tabs 36.

[0038] Indeed, for this last point, the tabs 36 which are both deformable but made of a semi-rigid material limit or even prevent the transverse movements of the cage 2 relative to the pile, these transverse movements being represented by the arrows F1 and F2 in figure 6 . Thus, the walls 23 of cage 2 remain at a distance from the mussels placed on pile A, since cage 1 is centered, which also helps keep predators at a distance.

[0039] Preferably, also the width L1 of a side wall 23 is sufficient so that, once the cage 1 is placed on the pile A, the different side walls 23 of the cage 1 do not touch the mussels, even when they have reached their adult size. This distancing of the walls of the cage 1 from the mussels further reinforces the protective action of the cage against predators.

[0040] Preferably, the width L1 of a side wall 23 is between 35 cm and 45 cm, preferably equal to 40 cm.

[0041] Furthermore, preferably the height H1 of the body 2 is adapted to the average height of the shellfish farms wrapped around the pile A. For example, H1 is preferably between 3m and 4m.

[0042] Advantageously also the cage 1 has one or more handling handles 24, fixed for example on the body 2, (only one handle being visible on the figure 6 ). Such a handle can, for example, be a textile strap.

[0043] A second embodiment of the invention will now be described in connection with the figure 7 .

[0044] In this case, the protective cage 1 comprises a body 2' and the device for closing the body 2' is no longer a cover 3 but flaps.

[0045] The parts of body 2' which are common to body 2 bear the same references increased by the prime sign and will not be described in detail again.

[0046] Thus, the body 2' comprises an upper end 21', a lower end 22', meshes 20', side walls 23' and one or more handles 24'.

[0047] Furthermore, the upper end 21' and / or the lower end 22' of the hollow body 2' is (are) provided with cutouts forming flaps 25', for example four flaps 25'.

[0048] The flaps 25' are folded towards the inside of the body 2' (towards its central axis X-X') and are held in the folded position by one or more ties 4.

[0049] As a purely illustrative example, the link 4 may have two strands 40 which are each fixed at one of their first ends to the body 2' and the other two ends of which meet and are fixed to a coupling element 41. This coupling element 41 in the form of an elongated bar may be engaged in a loop 42 fixed to the face of the body 2' opposite that on which the first ends of the strands 40 are fixed. The flaps 25' are thus held in the folded position.

[0050] This set of flaps 25' and link 4 plays the same role as cover 3, namely: to close the end of the body 2' since the flaps 25' fitted with mesh 20' prevent predators from accessing it, to allow the passage of the pile A between the flaps 25', and to center the hollow body 2' in relation to this pile A.

[0051] For this purpose, the flaps 25' are sized and configured so that once folded, they provide between them a central opening 26' allowing the passage of the pile A and so that their free ends 27' (their edges) are in contact with the pile A. Given the semi-rigidity of the plastic material which constitutes this body 2', and the fact that the ends 27' are in contact with the pile, the lateral movements (arrows F1 and F2) of the cage 1 relative to this pile A are limited, or even prevented. This end 27' can also possibly be folded back slightly (like a tab 36) so that the flap 25' is pressed against the pile A, over part of its length (taken from the wall 23' to the free end 27').

[0052] Although not shown in the figures, it would also be possible to have a body provided with a cover 3 at one of its ends and flaps 25' at its other end.

[0053] Whatever the embodiment of the cage 1, it will be noted that its installation or removal is easy since it is sufficient to slide it around the pile. In addition, the presence of the closing device positioned at the lower part of the body 2, 2' advantageously allows the recovery of mussels which have become detached from the rope C on which they were initially fixed. This same lower closing device makes it possible to dispense with the use of the Tahitian F of the prior art, since it also prevents access by crabs.

[0054] Advantageously, the semi-rigid plastic material used for the manufacture of the body 2, 2' and the covers 3 is a shape memory material.

[0055] The shape memory nature of this material allows the body 2, 2' of the cage 1 to be preformed hot on a template to give it its section, in particular its square section, and allows it to be folded flat by bringing one of its edges closer to the diametrically opposite edge. This allows for reduced storage space.

[0056] The semi-rigid nature of the material gives it both sufficient stiffness for the installation of the cage and sufficient flexibility to withstand sea shocks without being destroyed.

[0057] Preferably, this material is a thermoplastic polymer, more preferably high-density polyethylene. This type of material has the advantage of having very good mechanical strength, very good UV resistance, being insensitive to the marine environment, being virtually unbreakable, resistant to shocks and abrasion even when cold.

[0058] In addition, it is chemically inert and non-toxic for food use and prevents algae growth. Finally, it is recyclable.

[0059] It will be noted that, regardless of the type of closing device, the tabs 26 or the flaps 25' constitute positioning elements of the cage which act as spacers between the walls 23 of the body 2, 2' of the cage and the breeding support A due to the rigidity provided by the semi-rigid material. In addition, these positioning elements 26 or 25', due to the fact that they retain a certain flexibility provided by the semi-rigid material, can deform more or less to allow the cage 1 to be placed and removed from the breeding support A and adapt to the different dimensions of the breeding supports A, depending on whether these are stakes, ropes or lines.

Claims

1. Protective cage (1) for protection against shellfish predators, configured to be arranged on a shellfish rearing support, such a stake, a rope or a longline, these shellfish being in particular mussels, characterized in it comprises: - a hollow, elongated body (2, 2') with a lattice structure defining openings, such as meshes (20, 20'), the dimensions of which are configured to prevent the predatory action of the said predators, this hollow body (2, 2') being open at its two opposite ends, known respectively as the lower end (22, 22') and the upper end (21, 21'), and - two devices (3, 25') for closing the hollow body (2, 2'), one of the two closing devices being fixed to lower end (22, 22') of the body and the other device to the upper end (21, 21') of the body, each closure device (3, 25') being configured to at least partially close off the end of the hollow body (2, 2') while presenting an opening (5, 26') allowing the passage of the said rearing medium through this closure device and being configured to enable the hollow body (2, 2') to be centered with respect to this support and maintaining this centering, said hollow body (2, 2') and the two closing devices (3, 25') being made of semi-rigid plastic, said cage being characterized in at least one of said closing devices comprises a cover (3) provided with cut-outs (35) extending radially from its center, so as to form a plurality of deformable tongues (36), these tongues (36) being able to deform to allow the rearing support to pass through and to be able to press against it over at least part of their length, in order to ensure that the hollow body (2) is centered with respect to the said rearing support and that this centering is maintained.

2. Protective cage (1) as claimed in claim 1, characterized in that the cover (3) comprises a plate (31) provided on its periphery a plurality of orifices (33) allowing the passage of fasteners (34) for attaching said cover to lower end (22) and / or the upper end (21) of the body (2).

3. Protective cage (1) according to Claim 1 or 2, characterized in that the upper end and / or the lower end of the hollow body is or are provided with cut-outs forming flaps (25') and in that the said closure device is formed by these flaps (25') which are folded towards inside of the body (2') and held in position folded by ties (4), the flaps (25') being dimensioned and configured so that once folded, they form an opening (26') between them which allows the said rearing support to pass through and that their free ends (27') are in contact with this rearing support, in order to ensure the centering of the hollow body with respect to the said rearing support.

4. Protective cage (1) according to any one of the preceding claims, characterized in that the hollow body (2, 2') is square in cross-section and has four side walls (23, 23').

5. Protective cage (1) according to claim 4, characterized in that each side wall (23, 23') has a width of between 35 cm and 45 cm, preferably equal to 40 cm.

6. Protective cage (1) according to any one of the preceding claims, characterized in that the meshes (20, 20') of the body (2, 2') are diamond- or square-shaped, one diagonal (D1) of which has a length of between 14 mm and 40 mm and the other diagonal (D2) of which has a length of between 14 mm and 40 mm.

7. Protective cage (1) according to any one of the preceding claims, characterized in that it is provided at least one gripping handle (24, 24').

8. Protective cage (1) according to any one of the preceding claims, characterized in that the semi-rigid plastic material is a shape memory material.

9. Protective cage (1) according to any one of the preceding claims, characterized in that the semi-rigid plastic material is high density polyethylene.