Patent Publication Number: US-2020281170-A1

Title: Device for rearing aquaculture animals at sea

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims benefit under 35 USC § 371 of PCT Application No. PCT/EP2018/079467 entitled DEVICE FOR REARING AQUACULATURE ANIMALS AT SEA, filed on Oct. 26, 2018 by inventors Eric Marissal and Lila Pincot. PCT Application No. PCT/EP2018/079467 claims priority (i) of French Patent Application No. 17 60134, filed on Oct. 27, 2017, and (ii) of PCT Application No. PCT/EP2018/077223 filed on 5 Oct. 2018. 
    
    
     FIELD OF THE INVENTION 
     The invention generally relates to devices for rearing aquaculture animals at sea, in particular shellfish and more particularly oysters. 
     BACKGROUND OF THE INVENTION 
     In the majority of oyster farming countries, oysters are consumed shucked. There cooked before being consumed. In France, and in other countries, the oysters are consumed alive in their shells. These two different consumption modes have contributed to two different rearing types. Indeed, raw consumption in the shell requires irreproachable quality in the shape of the latter, less importance being given to the quality of the meat. To consume the shucked meat, no importance is given to the shape of the oyster. 
     Thus, in shucked consumption, the consumer requires a very meaty fish, which may retain a certain volume and texture after cooking, like for mussels. In the overwhelming majority of cases, the oysters are then reared in open water, adhered on their original support up to a sufficient size and age. They are harvested in appropriate periods for the quantity of meat and quality of fattening to meet consumer expectations. 
     In the case of oysters consumed raw in their shells, zootechnics have turned toward rearing oysters one by one, in enclosures able to be shaken regularly to prevent them from sticking to one another. 
     In order to allow these manipulations, the rearing areas are delimited exclusively in the intertidal area allowing access at low tide by personnel responsible for mixing the enclosures. These enclosures are generally pouches made from plastic mesh, placed on tables made from steel bars anchored on the beach. Thus concentrated and manipulated, the oysters grow correctly, but only very rarely achieve a meat quality equivalent to what the informed consumer is seeking, the latter being accustomed to consuming shucked oysters. 
     The drying area, that is to say, the intertidal area, is characterized by the strength of the waves, which in turn depends on the exposure of the coastline in question to the wind and the swell of the sea. On rare sites, it is thus possible, due to particularly powerful and regular mixing by the waves, to obtain not only oysters that are rolled enough in the rearing pouches for their shells to be eroded, rounded and well hollowed out, but also to have an exceptional meat content. These oysters are described as “super special”. The phenomenon involved is simple: when the food capacity of the oyster is satisfied, it always, up to a certain age (3 years), favors the allocation of energy to shell growth, to the detriment of fattening. On sites that are highly exposed to the waves, the fact that the shells are rolled in the rearing enclosures very regularly during the ebb tide, when the enclosures emerge in the waves, makes it possible to break part of the daily shell growth and to require the animal to favor growth of the shell in terms of thickness, which is slower, but guarantees a hollow and rounded shape. This operation would be impossible to do by hand because of the operating time at low tide, in light of the time needed by the personnel to perform it on large rearing areas. 
     At the same time, the proportion of energy not allocated to shell growth is reoriented toward fattening, thus favoring a high meat content, characterized by the “super special” quality. 
     This quality can be quantified as a filling rate of the mantle cavity of 60% after opening and 10 minutes of drainage. This combination of quality of shape and high meat content constitutes the very top of the line, which, consumed raw, is greatly appreciated by consumers in countries around the world. 
     Unfortunately, the sites where this rolling work of the shells is performed naturally in conventional enclosures of the oyster farming pouch type are rare. These sites must in fact have rich enough food and strong and constant enough agitation, but without being excessive, in order to avoid total destruction of the rearing site in case of storm. 
     For several years, a number of oyster farmers have had the idea to create so-called hanging rearing enclosures, of the swing chair type, in which the oysters would be more easily set in motion than in the oyster farming pouches conventionally fastened on the tables. 
     The enclosures are suspended from cables stretched horizontally, or below steel bars supported by oyster farming tables. They are very mobile, and are therefore able to transfer, to the oysters that they contain, the movement imparted by the marine currents and by waves of lesser amplitude than those necessary for the mixing of the oysters in the fixed enclosures. 
     There are several models of hanging enclosures: most are tubular enclosures, which may or may not be provided with a door at one of their ends, and suspended from cables fastened to their apex. 
     These models have a number of serious handicaps, which limit their usage tremendously. 
     These enclosures are very fragile. They are effective to mix oysters under moderately harsh conditions (sea current, swell, etc.), but do not withstand the harsh conditions accepted by fixed enclosures. They are therefore only usable in a semi-lagoonal, protected environment, and therefore can only be used in a very small proportion of oyster rearing sites to produce oysters in the French style. 
     Secondly, in light of the oscillating movement, all of these enclosures have spontaneously been designed with a cylindrical shape that leaves only a small surface area available for a significant mass of oysters. Indeed, the oysters accumulating at the lowest point of the enclosure, they have a small surface area to spread out. Once the growth is sufficient to fill half the enclosure, the oysters pile up and the movements are no longer sufficient to roll the oysters. The rearing naturally reorients itself toward a deterioration of the shell and meat quality. 
     Third, a secondary consequence of the cylindrical shape is the stacking of the oysters, the latter not being able to roll in the enclosure unless the agitation conditions are very strong. This is fairly incompatible with the fragility of the material. 
     Fourth, these cylindrical enclosures have a significant bulk, and therefore take up tremendous storage space. This limits the transport capacity of the oysters, and complicates the possibility of stacking the enclosures in a stable manner on ships or handling trailers compared with the flat oyster farming pouches, which stack easily and have only a slightly larger volume than that of the transported oysters. 
     Fifth, these enclosures are very difficult to clean, since they have a multitude of faces and an inner volume that is inaccessible to the washing jet. 
     Sixth, they cannot be turned over, and therefore are dirtied by algae on the illuminated face and by ascidians on the bottom face, sheltered from the sun. This quickly causes the mesh to be covered, thus depriving the oysters inside from the flow of water necessary for them to be properly fed. 
     To address part of the above difficulties, FR 2,576,484 proposes to add a float to the outside of the enclosure. Thus, the enclosure turns over between the high tide, during which it floats, and the low tide, during which it hangs. It is clear that this turning over allows better mixing of the oysters, in particular upon the emergence at ebb tide. However, such an assembly is only usable in the tidal zone, that is the say, in the zones that are exposed at low tide. 
     A certain number of tests have been conducted in deep water in cages containing a large number of rearing enclosures, either stationary like oyster farming pouches, or mobile with swing chairs. The tests to date have all yielded poor results. Indeed, the exceptional growth hoped for by constant immersion is indeed present, but the underwater immobility of these structures leads to oysters that reach commercial size very young and in record time, and which are therefore very fragile, very deformed and which have very mediocre meat content. However, rearing in a functional cage would have major advantages: significant shortening of the rearing duration, labor savings and better ergonomics through the industrialization of the work of many enclosures at the same time in one cage. 
     SUMMARY OF THE DESCRIPTION 
     In this context, the invention aims to propose a rearing device at sea that procures better mixing and that can be used over a larger zone. 
     To that end, the invention according to a first aspect relates to a device for rearing aquaculture animals at sea, the device comprising:
         a framework provided to be placed on the sea bed;   at least one rearing enclosure internally delimiting a volume for receiving the aquaculture animals;   a connection connecting said at least one rearing enclosure to the framework, permitting a rotation of said at least one rearing enclosure with respect to the framework about at least one substantially horizontal axis of rotation;   a float device connected to said at least one rearing enclosure by a flexible connection of a length chosen such that, when the flexible connection is vertically tensioned, the float device is located in the intertidal zone.       

     The invention is therefore based on the combination of a structure having at least one pivoting enclosure, placed on the sea bed, typically in deep water, and a float at a chosen height in the interval of the tidal range. The structure and the enclosure are of any suitable type, the enclosure for example being able to be a simple oyster farming pouch fixed on a pivoting metal tray. 
     The length of the flexible connection is chosen so that, at least at one moment during the cycle of the tide, the float floats on the surface of the water with the flexible connection tensioned, such that the movements of the water due to the waves are transmitted by the float and the flexible connection to the rearing enclosure. 
     The rearing device can thus be used in deep water, that is to say, in a zone where the rearing enclosures are not exposed at low tide. It becomes possible to use vast maritime surfaces outside the tidal zone, thus resolving usage conflict problems. 
     The device may further have one or more of the features below, considered individually or according to any technical possible combination(s):
         the rearing device comprises several rearing enclosures located one above the other, each connected to the framework, by a connection permitting a rotation of said at least one rearing enclosure with respect to the framework about at least one substantially horizontal axis of rotation, all of the rearing enclosures being connected to the same float device;   the flexible connection directly connects the upper rearing enclosure to the float device;   each rearing enclosure is directly connected by an intermediate connection to the rearing enclosure immediately above and/or to the rearing enclosure immediately below;   the rearing enclosures are connected to one another by intermediate connections comprising a rigid member and hinges of the rear enclosures to the rigid member;   the hinges are configured to permit a pivoting of the enclosures relative to the rigid member;   a limiting device connects the upper rearing enclosure to the framework, limiting the downward travel of the rearing enclosures, the limiting device preferably being a flexible link;   a limiting device connects one of the rearing enclosures to the framework, limiting the upward travel of the rearing enclosures, the limiting device preferably being a flexible link;   said at least one rearing enclosure has a proximal edge and a distal edge that are opposite one another, the connection connecting the proximal edge to the framework, the float device being connected to a zone of said at least one rearing enclosure located near the distal edge;   the connection permits a rotation of said at least one rearing enclosure about a first, substantially horizontal axis of rotation, and a rotation of the first axis of rotation with respect to the framework about a second axis of rotation substantially parallel to the first axis of rotation;   the connection includes at least one connection member of the connecting rod type, mounted pivoting on said at least one rearing enclosure about the first axis of rotation and mounted pivoting on the framework about the second axis of rotation;   said at least one rearing enclosure has a substantially flat lower bottom, parallel to the first and second axes of rotation;   the float device comprises a string of floats, the string including a plurality of floats, mounted one after the other along a flexible link, a lower end of which is secured to the flexible connection.       

     According to a second aspect, the invention relates to an assembly comprising a plurality of rearing devices as defined above, the lengths of the flexible connections of the rearing devices being chosen so that, when said flexible connections are tensioned vertically, the float devices of the rearing devices are located substantially at the same level. 
     According to a third aspect, the invention relates to a method for rearing aquaculture animals at sea, the method comprising a step for installing at least one rearing device as defined above at sea, the framework being positioned on the sea bed, the length of the flexible connection being chosen such that the float device, when the flexible link is vertically tensioned, is located in the intertidal zone. 
     Advantageously, several devices as defined above are installed at sea in the installation step, the frameworks of said rearing devices are placed on the tidal zone at different respective levels, the length of the flexible connections of said rearing devices being chosen so that, when said flexible connections are vertically tensioned, the float devices of the rearing devices are located substantially at the same level. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the invention will emerge from the detailed description thereof provided below, for information and non-limitingly, in reference to the appended figures, in which: 
         FIG. 1  is a simplified schematic illustration a rearing device according to a first embodiment of the invention; 
         FIG. 2  schematically shows the upward movement of one of the rearing enclosures of the device of  FIG. 1 , 
         FIG. 3  illustrates the downward movement of the same rearing enclosure; 
         FIG. 4  is a more precise illustration of several enclosures of the rearing device of  FIG. 1 , in top view; 
         FIGS. 5 and 6  are front and side views, respectively, of a half-enclosure used to form the enclosures of  FIG. 4 ; 
         FIGS. 7 and 8  are enlarged views of details of the half-enclosure of  FIGS. 5 and 6 ; 
         FIG. 9  is a side view of a connecting member of the device of  FIG. 4 , before fastening to the rearing enclosure; 
         FIGS. 10 to 12  are perspective views of the connecting member of  FIG. 9 , respectively, mounted on the rearing enclosure, in the stable open position, and closed around the framework; 
         FIG. 13  is a top view of the connecting member of  FIG. 12 , after fastening to the rearing enclosure and the framework; 
         FIG. 14  is a perspective view of one of the rearing enclosures of  FIG. 4 , showing the reinforced stop zones and the blocking members; 
         FIG. 15  is a simplified schematic perspective illustration of the rearing device of  FIG. 1 , showing how it is possible to turn over the rearing enclosures; 
         FIG. 16  illustrates a second embodiment of the invention, in a situation where the float is located at mid-tide at the surface of the sea; 
         FIGS. 17 and 18  are schematic side illustrations of the rearing device of  FIG. 16 , at high tide and at low tide; 
         FIG. 19  illustrates how different rearing devices according to  FIG. 16  can be positioned along the tidal zone; 
         FIG. 20  illustrates a variant of the second embodiment, in which the system ensuring the hanging of the enclosures comprises a string of floats positioned in the intertidal zone and an inner float housed in each enclosure; 
         FIG. 21  illustrates another arrangement mode of the frameworks on which the enclosures are mounted; 
         FIG. 22  shows another variant of the rearing device of  FIG. 16 . 
     
    
    
     DETAILED DESCRIPTION 
     The invention relates to a device for rearing aquaculture animals at sea. These animals are typically shellfish, and are more particularly oysters. In a variant, the shellfish are all types of bivalves such as clams, mussels, or any other type of shellfish. 
     This device is provided for rearing at sea. This rearing can be done offshore from coasts or in sluices, estuaries or rias, or in ponds communicating with the sea, or in any other appropriate location. 
     As illustrated in  FIGS. 1 to 3 , the rearing device  1  comprises:
         a framework  3 ;   at least one rearing enclosure  5  internally delimiting a volume  7  for receiving the aquaculture animals  9 ;   a float device  10  connected to said at least one rearing enclosure  5 ;   a connection  13  connecting said at least one rearing enclosure  5  to the framework  3 .       

     The framework  3  is provided to be placed at the bottom of the sea. Typically, it rests on the bottom  15  of the sea. It is stationary relative to the sea bed  15 . 
     In the first embodiment, the framework  3  includes a plurality of metal bars  17  that are parallel to one another and spaced apart from one another at least horizontally. 
     For example, the metal bars  17  are placed at the same distance from the bottom  15 . 
     The framework  3  for example includes ingots  19  resting on the sea bed  15 , supporting rigid posts  21  to which the metal bars  17  are rigidly fastened. The metal bars  17  are regularly spaced apart from one another along a direction that is horizontal in  FIG. 1 . 
     In the first embodiment, the rearing device includes a plurality of rearing enclosures  5 , each positioned between two metal bars  17 . 
     Each rearing enclosure  5  has a lower bottom  23 , which is substantially flat. 
     It preferably has a substantially flat upper bottom  25 , which is parallel to and opposite the lower bottom  23 . 
     The lower and upper bottoms  23 ,  25  have a determined separation between them. This separation is taken along a direction substantially perpendicular to the two bottoms. 
     The lower and upper bottoms  23 ,  25  also each have a length and a width greater than three times said separation. The length is taken along a direction contained in the plane in which the upper or lower bottom fits. The width is taken along a direction contained in said plane and perpendicular to the length. 
     Preferably, the length and the width are greater than five times the separation, still more preferably greater than ten times the separation. 
     Thus, the rearing enclosure has a flat general shape, and has a large surface area in light of its thickness. It thus has the general shape of a pouch typically used for rearing oysters. 
     For example, the rearing enclosure has a length on the order of 1 meter, a width on the order of 500 mm, and a height on the order of 50 mm. 
     As shown in  FIGS. 4 to 6 , the rearing enclosure preferably comprises two half-enclosures  27 , one defining the lower bottom  23  and the other the upper bottom  25 . 
     The two half-enclosures together delimit the volume  7  for receiving aquaculture animals. 
     They are fastened to one another removably, using means that will be described later. 
     Advantageously, the two half-shells  27  are identical to one another. 
     They are preferably made from a plastic material, for example from polypropylene. 
     They are typically obtained by injection of the plastic material. The fact that the two half-enclosures are identical to one another therefore makes it possible to manufacture the two half-enclosures with the same mold, and therefore allows a particularly economical production. 
     The half-enclosures  27  have a generally concave shape. The concavities of the two half-enclosures face toward one another when they are fastened to one another in order to form the rearing enclosure. 
     Each half-enclosure  27  comprises a substantially planar part  29  defining the upper bottom or the lower bottom depending on the case, an annular flat edge  31  surrounding the planar part  29 , and a wall with a closed contour  33  connecting the planar part  29  to the flat edge  31  ( FIGS. 5 and 6 ). The wall with a closed contour  33  connects an outer edge of the planar part  29  to an inner edge of the flat edge  31 . In other words, the flat edge  31  forms a collar, extending outward from the wall  33 . 
     The flat edge  31  fits in a plane parallel to the planar part  29 , defining the contact plane between the two half-enclosures when they are assembled to make up the rearing enclosure. 
     The planar part  29  and the side wall  33  are pierced with multiple openings, not referenced, small enough that the aquaculture animals cannot escape from the rearing enclosure, but large enough to allow water to circulate between the inside and the outside of the rearing enclosure. 
     The planar part  31  and the side wall  33  are reinforced by ribs  34 . 
     Advantageously, the two half-shells  27  can be nested in one another. This makes it possible to stack a large number of half-enclosures and to store them in a smaller volume. 
     To do this, the side wall  33  is flared, and diverges from the planar part  29  toward the flat edge  31 . 
     In the illustrated example, the planar part  29  is rectangular, and t he flat edge  31  is delimited by a rectangular outer edge and by an inner edge that is also rectangular. 
     In a variant, the planar part  29  and the flat edge  31  have any appropriate shape: square, circular, oval, etc. 
     Preferably, the two half-enclosures  27  are fastened to one another by blocking members, typically pins  36  shown in  FIG. 14 . To that end, the flat edge  31  has slits  35  distributed on at least two opposite sides of the planar part  29 . The slits  35  are provided to receive the pins. To make up the rearing enclosure  5 , the two half-enclosures  27  are placed with their respective edges  31  against one another. The slits  35  of the two half-enclosures then coincide and it is possible to engage the blocking members there. 
     In order to strengthen the fastening of the two half-enclosures  27  to one another, each half-enclosure includes hooks  37  ( FIG. 7 ) and orifices  39  for receiving the hooks of the other half-enclosure ( FIG. 5 ). 
     The orifices  39  are cut into the flat edge  31 . They are distributed along at least two opposite sides of the planar part  29 , for example the sides that do not bear the slits  35 . The hooks  37  are borne by the flat edge  31  and protrude away from the planar part  29  relative to the flat edge  31 . 
     As shown in  FIG. 7 , they are generally L-shaped, with a segment  39  oriented substantially perpendicular to the flat edge  31 , extended by a terminal segment  41  extending along a direction substantially parallel to the flat edge  31 . 
     The terminal segments  41  of all of the tabs  37  point in the same direction. 
     The hooks  37  of each half-enclosure are provided to be engaged in the orifices  39  of the other half-enclosure following a movement substantially perpendicular to the planar parts  29  of the two half-enclosures. They are next engaged around the edges of said orifices  39  by a translational movement of one of the half-enclosures relative to the other half-enclosure along a longitudinal direction. 
     At the end of this movement, the flat edge  31  of each half-enclosure  27  is pinched between the terminal segments  41  and the flat edge  31  of the other half-enclosure  27 . The hooks  37  can no longer be released from the orifices  39  by a movement perpendicular to the planar parts  29  of the half-enclosures. 
     At the end of this translational movement, the slits  35  of the two half-enclosures coincide with one another. The blocking members can then be inserted into these slits and thus block any possibility of translation of the two half-enclosures, at least along the longitudinal direction, and typically along all directions, the latter then being solidly secured by the hooks. 
     In order to still further strengthen the connection between the two half-enclosures, additional hooks  43  are provided on a segment  45  of the flat edge extending transversely ( FIGS. 5 and 8 ). These additional hooks  43  have a general shape that is substantially identical to that of the hooks  37 . The additional hooks  43  are borne by the outer edge of this flat collar  31 . Their terminal segments point longitudinally, along the same direction as the terminal segments  41  of the hooks  37 . The transverse segment  47  of the flat edge  31 , located opposite the transverse segment  45 , has notches  49  on its outer edge. When the two half-enclosures  27  are assembled to one another as described above, namely a first movement perpendicular to the planar parts  29  and a second longitudinal movement, the additional tabs  43  of each half-enclosure engage in the notches  49  of the other half-enclosure and adapt around the transverse segment  47  of the other half-enclosure. The flat edge  31  of each half-enclosure  27  is thus pinched between the additional tabs  43  and the flat edge  31  of the other half-enclosure  27 . 
     Thus, the two half-enclosures  27  are connected to one another by a particularly strong connection. The stiffness of the rearing enclosure is increased. This is in particular due to the existence of a large number of fastening points of the two half-enclosures  27  to one another, distributed around the upper and lower bottoms. 
     The connection  13  permits a rotation of each rearing enclosure  5  about a first, substantially horizontal axis of rotation R 1 , and a rotation of the first axis of rotation R 1  with respect to the framework  3  about a second axis of rotation R 2  substantially parallel to the first axis of rotation R 1  ( FIGS. 1 to 3 ). 
     More specifically, the connection  13  advantageously includes at least one connection member  51  of the connecting rod type, mounted pivoting on the rearing enclosure  5  about the first axis of rotation R 1  and mounted pivoting on the framework  3  about the second axis of rotation R 2 . 
     As shown in  FIG. 4 , the connection  13  typically includes two connecting members of the connecting rod type  51  for each rearing enclosure, each connecting member  51  connecting the rearing enclosure  5  to the framework. The first axes of rotation R 1  of the two connecting members of a same rearing enclosure are aligned with one another. Likewise, the second axes of rotation R 2  of the two connecting members  51  of the same enclosure  5  are aligned with one another. 
     The rearing enclosure  5  has a proximal edge  55  and a distal edge  57  that are opposite one another, facing toward the two metal bars framing the rearing enclosure  5 . 
     In the illustrated example, the proximal edge and the distal edge are longitudinal. 
     These edges  55 ,  57  are made up of segments of the flat collars  31  of the two half-enclosures pressed against one another. 
     The connection  13  connects the proximal edge  55  to the framework  3 . 
     More specifically, each connecting member  51  connects the proximal edge  55  to the metal bar  17  adjoining said proximal edge. 
     As shown in  FIGS. 4, 12 and 13 , the connection  13  includes, for each connecting member  51 , a sleeve  53  fastened to the metal bar  17  adjoining the proximal edge  55  of the rearing enclosure  5 . The connecting member  51  is mounted pivoting around the sleeve  53 . The metal bar  17  thus constitutes the second axis of rotation R 2 . 
     This sleeve  53  completely surrounds the metal bar  17 . For example, it is made up of two generally semi-cylindrical half-shells, placed on either side of the metal bar  17 . The two half-shells are rigidly fastened to one another using any suitable means, for example by pins. The sleeve  53  is typically made from polyolefin. The wear of the connecting member  51  is thus reduced, which is not in direct contact with the metal bar. 
     As shown in  FIGS. 9 to 13 , each connecting member  51  advantageously includes two half-clamps  59  that are independent of one another. The two half-clamps  59  together define two bearings  61 ,  63 , which are substantially parallel to one another. The bearing  61  is intended inwardly to receive the sleeve  53 . The bearing  63  is intended inwardly to receive a cylinder  65  formed on the proximal edge  55  of the rearing enclosure. 
     Each half-clamp  59  is therefore generally W-shaped, with three blocks  67 ,  69  and  71  delimiting two hollows  73  and  75  between them. The hollows  73  and  75  have semi-cylindrical shapes. When the two half-clamps are assembled to one another, the hollows  73  of the two half-clamps make up the bearing  61 , and the hollows  75  of the half-clamps make up the bearing  63 . 
     The two half-clamps  59  are able to be mounted on the rearing enclosure  5  in a stable open position, shown in  FIG. 11 , in which the half-clamps  59  are connected to one another by a pivot link  77 . 
     The axis of rotation of the pivot is substantially parallel to the first axis of rotation. 
     To allow the two half-clamps to be placed, the proximal edge  55  of the trap has two orifices  78  along the cylinder  65 . These orifices are offset toward the inside of the enclosure relative to the cylinder  65 . 
     The pivot link  77  includes two plates  79 , parallel to one another, formed on the block  71  of one of the half-clamps ( FIGS. 5 and 9 ). Each plate  79  bears trunnions  81  on its two opposite faces. The four trunnions  81  are aligned. 
     The block  71  of the other half-clamp forms two pairs of flanges  83 , each pair of flanges being provided to receive one of the plates  79  between its two flanges. Cradles for receiving trunnions  81  (not shown) are hollowed out in the opposite faces of the two flanges of a same pair. 
     The half-clamps  59  are first mounted on the enclosure  5  as illustrated in  FIG. 10 . 
     One can see that the plates  79  are each engaged in one of the orifices  78 . They are engaged between the flanges  83  of the other half-clamp  59 . The half-clamps form an angle of about 90° with one another. The rotation of the two half-clamps relative to one another in the direction of an opening of the clamp is blocked by reliefs formed on the half-clamps  59 . Conversely, the two half-clamps  59  are free to pivot relative to one another about the pivot link  77  in the direction of a closure. It should be noted that the cradles formed in the flanges  83  are provided so that the engagement of the trunnions  81  is easy, but the removal of the trunnions  81  outside the cradles requires a significant force, so as to prevent the two half-clamps from separating from one another involuntarily. 
     From the position of  FIG. 10 , the half-clamps  59  can pivot about the pivot link  77  to the stable open position, shown in  FIG. 11 . Each half-clamp  59  includes an arm  84 , bearing a relief  84 R at its end. In the open position, the relief  84 R of each half-clamp is wedged reversibly in a housing  84 M of the other half-clamp. This makes it possible to keep the half-clamps  59  in the open position, without preventing the rotational movement of the half-clamps toward one another from being extended. 
     Thus, from the stable open position ( FIG. 11 ), the two half-clamps can be closed around the framework  3  by pivoting around the pivot link  77  ( FIG. 12 ). The arms  84  slide in the housings  84 M. 
     The hollows  75  are then placed around the cylinder  65 , and the hollows  73  around the sleeve  53 . In this position, the intermediate blocks  69  of the two half-clamps  59  bear against one another, and the blocks  67  of the two half-clamps  59  also bear against one another. The two half-clamps  59  are locked in this position by pins G shown in  FIG. 13 , engaged in aligned orifices O of the two half-clamps  59 . It will therefore be understood that the mounting of the connecting member  51  is particularly simple. It allows an easy placement of the rearing enclosures  5  on the framework  3 . 
     The rearing enclosure  5  preferably comprises at least one stop zone  85  ( FIG. 14 ), cooperating with the connecting member  51  so as to limit the rotational travel of the rearing enclosure  5  relative to the connecting member  51  about the first axis of rotation R 1 . 
     Typically, the rearing enclosure  5  includes two stops zones  85 , limiting the rotational travel of the rearing enclosure  5  relative to the connecting member  51  in both opposite directions of rotation. 
     These zones  85  are strengthened due to the fact that they include a larger number of ribs  34  than the other zones of the enclosure  5 , so as to stiffen the structure of the rearing enclosure  5  at said zones  85 . 
     For example, these zones  85  are the zones of the peripheral wall  33  located across from each connecting member. The zone  85  arranged on the peripheral wall  33  of one of the half-traps limits the rotation in one direction, and that formed on the wall  33  of the other half-trap limits the rotation in the other direction. These stops thus ensure an impact effect at the end of travel favoring the loosening and movement of the aquaculture animals on the tray. 
     Furthermore, the rearing device  1  advantageously includes a limiting device  86 , limiting the travel of the rearing enclosure  5  relative to the framework  3  along the vertical direction ( FIG. 4 ). 
     The limiting device  86  comprises at least one flexible link  87  that connects the framework  3  to the rearing enclosure  5 . 
     Preferably, the or each flexible link  87  is resilient. This makes it possible to damp the movement of the rearing enclosure in the vertical direction. 
     Typically, each rearing enclosure  5  is connected by two flexible links  87  to the framework  3 . 
     Preferably, each flexible link  87  connects the distal edge  57  of the rearing enclosure  5  to the framework  3 . More specifically, the link  87  connects the distal edge  57  to the metal bar  17  located opposite the connecting members  51 . Thus, the rearing enclosure is connected on the one hand by the connecting members  51  to one of the metal bars  17 , and on the other hand by the flexible links  87  to the other metal bar  17 . 
     As shown in particular in  FIGS. 4 and 5 , the distal edge  57  has orifices  89  allowing the passage and fastening of one end of the flexible link  87 . 
     Typically, the ends of the flexible link  87  are fastened to the sleeve  53  on which the adjacent rearing enclosure  5  is hinged. As illustrated in  FIG. 4 , the ends of the flexible link  87  are wound around the sleeve, in grooves  90  formed by the sleeve  53 . 
     The sleeves  53  can further include notches  88 , visible in  FIG. 12 , making it possible to attach the flexible link to the sleeve. 
     It should be noted that the orifices  89  are identical and positioned in the same way as the orifices  78 . 
     More generally, it will be noted that each half-trap is symmetrical relative to a longitudinal median plane, perpendicular to the planar part  29 . 
     It is thus possible to mount the rearing enclosures in any direction. 
     In the first embodiment, each rearing enclosure  5  is equipped with its own float  11 , which constitutes the float device  10 . 
     The float device  10  is connected by a flexible connection  95  to the rearing enclosure  5 . 
     The flexible connection  95  is of any suitable type. The flexible connection  95  for example includes one or several cables, each connecting the float to the enclosure. In a variant, it includes lines, ropes, chains, or any other type of flexible link. 
     Typically, the flexible connection  95  connects the float device  10  to the distal edge  57  of the upper rearing enclosure, or to a zone of the rearing enclosure  5  located near the distal edge  57 . 
     The length of the flexible connection  95  is chosen such that the float device  10 , when the flexible connection is tensioned, is in the tidal range zone, that is to say, a level between the level of the water at low tide (MB in  FIG. 1 ) and the level of the water at high tide (MH in  FIG. 1 ). In other words, the length of the flexible connection is chosen so that, at least at one moment during the cycle of the tides, the float device  10  floats on the surface of the water with the flexible connection  95  tensioned, such that the movements of the water due to the tide and/or to the waves are transmitted by the float device  10  and the flexible connection  95  to the upper rearing enclosure. 
     The float device  10  is dimensioned to cause the enclosure containing the aquaculture animals to float until the end of the rearing, that is to say, when these animals have reached their maximum weight. The float device  10  can thus be adapted over the course of the rearing, for example by adding buoyancy as the mass of the aquaculture animals in the enclosures increases. 
     The operation of the rearing device will now be described in detail, more specifically in reference to  FIGS. 1 to 3 . 
     The rearing device is designed to transmit the movement of the waves to the rearing enclosures, and will cause the aquaculture animals to slide over a significant distance by causing them to roll over the inner surface of the enclosure and against one another, in particular during falling and rising tides. 
     In  FIG. 1 , the rearing device  1  is shown when the water level is such that the float devices  10  at the surface of the water with the flexible connections  95  tensioned. 
     The inner bottom  23  of each enclosure  5  is substantially horizontal. 
     The two axes of rotation R 1 , R 2  are substantially in a horizontal plane. 
     The flexible links  87  are not tensioned. 
     When the float device  10  is in a trough between two waves, as illustrated in  FIG. 3 , the vertical level of the float device  10  drops. 
     The rearing enclosure  5  adopts an inclined position, the proximal edge  55  connected by the connection  13  to the framework  3  remaining higher and the distal edge  57  being lower. The connection  13  permits the pivoting of the rearing enclosure  5  about the two axes of rotation R 1  and R 2 . 
     Due to the incline, in particular because the lower bottom  23  is inclined relative to the horizontal, the rearing animals  9  will roll on the inner bottom  23  and will roll against one another while accumulating toward the distal edge  57  of the rearing enclosure. 
     Because the connection  13  has two degrees of rotational freedom, the downward pivoting movement of the rearing enclosure  5  (arrow F 1  of  FIG. 3 ) is accompanied by a generally horizontal movement of the enclosure  5 , embodied by arrow F 2  of  FIG. 3 . This generally horizontal movement creates a shearing force at the contact between the aquaculture animals and the rearing enclosure, which amplifies the circulation of the rearing animals and permits them to slide and roll even with small inclines. This shearing force, when repeated, potentially makes it possible to loosen any rearing animals that may be stuck to the rearing enclosure. 
     Thus, the connection  13  makes it possible to convert the vertical movement of the water, due to the waves, into an agitation movement that is both vertical and horizontal, which, associated with the incline of the rearing enclosure  5 , permits the aquaculture animals to slide over the planar mesh of the enclosure while rolling over this mesh against one another. 
     Furthermore, the connecting members  51  at the end of travel abut against the stop zones  85  of the rearing enclosure, which further strengthens the shearing effect. This encourages the loosening of the rearing animals, in particular of the oysters that may have become stuck again by nacration between two agitation periods. 
     The limiting device  86  makes it possible to limit the vertical amplitude of the movement, which allows the farmer to adapt the system to the hydraulic conditions prevailing in the rearing zone and to the seasonality of the rearing. 
     It should be noted that the rearing enclosure  5  is driven in movements opposite those embodied by arrows F 1  and F 2  when the enclosure returns from its low position illustrated in  FIG. 3  to the intermediate position illustrated in  FIG. 1 . 
     As shown in  FIG. 2 , when the float device  10  is located at the top of a wave, the rearing enclosure  5  adopts an incline opposite that illustrated in  FIG. 3 . The distal edge  57  is located higher than the metal bar  17 , such that the aquaculture animals  9  slide over the lower bottom  23  toward the proximal edge  55 . The rearing enclosure undergoes a pivoting movement relative to the metal bar  17 , embodied by arrow F 3  in  FIG. 2 . This pivoting is done in an upward direction. Relative to the position of  FIG. 1 , the rearing enclosure  5  also experiences a movement in a generally horizontal direction, embodied by arrow F 4  in  FIG. 2 . Again, a shearing force is created between the aquaculture animals and the rearing enclosure, which encourages the movement and the rolling of the rearing animals  9  within the rearing enclosure  5 . 
     The connecting members  51  at the end of travel abut against the stop zones  85  provided to that end on the rearing enclosure  5 . The limiting device  86  limits the upward vertical travel of the rearing enclosure  5  with respect to the framework  3 . 
     The rearing enclosure  5  is driven in movements opposite those shown by arrows F 3  and F 4  when it returns from its extreme high position shown in  FIG. 2  to the intermediate position illustrated in  FIG. 1 . 
     When the tide is high, as illustrated in  FIG. 17  for another embodiment, the float device  10  is completely submerged, and is at a distance from the water level. The flexible connection  95  is tensioned. The rearing enclosure  5  is in its extreme high position. This position is defined by the limiting device  86 . 
     In the exemplary embodiments described above, this position is defined by the length of the flexible link(s)  87 , which are also tensioned. When the tide is high, as illustrated in  FIG. 18  for another embodiment, the rearing enclosure  5  is in its extreme low position, defined by the limiting device  86 . 
     In the exemplary embodiments described above, this position is defined by the length of the flexible link(s)  87 . The float device  10  floats on the surface of the water. The flexible connection  95  is not tensioned. 
     The installation level of the float device  10  relative to the height of the tidal range, that is to say, the height of the water at high tide and the height of the water at low tide, makes it possible to choose the operating conditions of the system. 
     Indeed, the tidal range is characterized by two parameters: its amplitude, variable from one day to the next (for example, in France, the strong tidal ranges alternate with the weak tidal ranges over a periodicity of 15 days) and the rising and falling speed of the water, which for example follows the rule of twelfths, which means that at the beginning or the end of the falling or rising tide, the rising and falling speed is three times slower than at mid-tide. As a result, depending on the altimetric installation of the float device relative to the tidal range, it will be possible either to obtain, in the upper bracket of the low-amplitude tidal ranges, a daily agitation over a long duration, or to obtain, in the lower bracket of high-amplitude tidal ranges, a low to very low frequency agitation over a long duration, or in the in-between space of the tidal range, a more or less frequent agitation of shorter duration. 
     It should be noted that the limiting device  86  also makes it possible to adjust the amplitude and duration of agitation of the aquaculture animals, in order to regulate the desired effect on the rearing animals. Indeed, the rearing enclosures  5  are only agitated for a limited period of the tide. They are agitated between the moment where the height of the peak of the waves is sufficient for the rearing enclosures to be lifted from their extreme low positions (shown in  FIG. 3 ), and the moment where the height of the troughs of the waves is such that the rearing enclosures are blocked in the extreme high position (shown in  FIG. 2 ). These extreme high and low positions are determined by the limiting device  86 . The greater the vertical amplitude of the movement of the rearing enclosures is, the greater the agitation duration and the more violent the agitation. 
     A second advantageous aspect of the first embodiment of the invention is shown in  FIG. 15 . As described above, the framework  3  includes a plurality of metal bars  17 , parallel to one another and evenly spaced apart from one another. The metal bars  17  are for example fastened to metal crosspieces  90 . Each rearing enclosure is positioned between two metal bars  17 . Its proximal edge  55  is connected by the connection  13  to one of the metal bars  17 , and its distal edge  57  is connected by one or several flexible links  87  to the other metal bar  17 . The adjacent rearing enclosure  5  is mounted in the same way. More specifically, the distal edge  55  of the adjacent rearing enclosure  5  is connected by the connection  13  to the metal bar  17  to which the first rearing enclosure is connected by the flexible link(s)  87 . Thus, each metal bar  17  is connected on the one hand by a connection  13  to a rearing enclosure  5 , and on the other hand by flexible links  87  to another rearing enclosure. 
     A continuous line of rearing enclosures  5  is thus formed. The rearing enclosures  5  can be turned over very easily to combat dirtying. Indeed, it is known that algae develop very easily on the faces of the rearing enclosures that face upward, that is to say, that are exposed to the sun. Furthermore, ascidians develop on the face of the rearing enclosure that is in the shade, that is to say, facing downward. 
     In order to turn over the rearing enclosures of the device according to the invention, it suffices to disconnect the links  87  connecting each rearing enclosure to the corresponding metal bar  17 . It is next possible to pivot the rearing enclosure  5  about the other metal bar, to which it is connected by the connection  13 . Then, the distal edge of the enclosure is connected to a new metal bar  17 , by the resilient links that have stayed in place. 
     A second embodiment of the invention will now be described in reference to  FIGS. 16 to 19 . Only the differences between the second embodiment and the first will be outlined below. 
     In the second embodiment, all of the rearing enclosures  5  of the rearing device  1  are connected to a same float device  10 . 
     The rearing enclosures  5  are superimposed above one another. 
     They are each connected to the framework  3  by their connection  13 . 
     Advantageously, the framework  3  comprises several metal bars  17  that are parallel to one another, spaced apart from one another at least vertically. 
     For example, the framework  3  includes a parallelepiped structure. This structure includes four vertical posts  91 , these posts preferably being secured to one another by an upper frame  93  and a lower frame  94 . The metal bars  17  are rigidly fastened by their opposite end to two of the posts  91 , and are superimposed along the vertical direction. The metal bars  17  are thus positioned on a large face of the rhomb. 
     A rearing enclosure  5  is connected to each metal bar  17 . 
     The metal bars  17  are evenly spaced apart from one another along the vertical direction. 
     The rearing enclosures  5  are placed inside the framework, and travel between the posts  91 . 
     According to one exemplary embodiment, the float device  10  includes a single float  11 . The float device  10  is connected by a flexible connection  95  to the upper rearing enclosure  5 , located highest in the stack of rearing enclosures. Intermediate connections  97 , typically cables or lines, link each rearing enclosure  5  to the rearing enclosure located immediately above and/or the rearing enclosure located immediately below in the stack. In a variant, these intermediate connections are rigid spacers, which for example pivot about axes located on the distal edge of the rearing enclosures. In some cases, a rigid connection can be a cohesion factor of the movement encouraging an equal agitation of the set of rearing enclosures. Indeed, a flexible connection could, in case of high-frequency agitation (chop), encourage, following the inertia of the set of rearing enclosures, the agitation of the upper rearing enclosures, resulting in an excessive agitation of the rearing animals of the upper enclosures versus an insufficient agitation of the rearing animals of the lower enclosures. 
     Typically, the flexible connection  95  connects the float device  10  to the distal edge  57  of the upper rearing enclosure. The intermediate connection(s)  97  connect the distal edges of the different rearing enclosures to one another. 
     The framework  3  rests on the bottom  15 . It is for example mounted on a pile driven into the bottom  15 . 
     The length of the flexible connection  95  is chosen such that the float device  10 , when the flexible connection is tensioned, is in the intertidal zone, that is to say, a level between the level of the water at low tide and the level of the water at high tide. The intermediate connections  97  are chosen with lengths such that, when the upper enclosure  5  pivots upward, it drives the enclosure located immediately below it, which in turn drives the immediately lower enclosure, etc. 
     Typically, the length of the intermediate connections  97  is chosen to be equal to the vertical separation between the metal bars  17 . 
     In the illustrated example, the float device  10  is connected to the upper rearing enclosure by two cables. Each rearing enclosure is connected to the enclosure immediately above and/or the enclosure immediately below by two intermediate connections  97 . 
     Furthermore, the limiting device  86  comprises at least one flexible link  99  connecting the upper rearing enclosure  5  to the framework and limiting the downward travel of said enclosure. In the illustrated example, the limiting device  86  comprises two flexible links  99  connecting the upper enclosure to the framework. 
     Furthermore, the limiting device  86  comprises at least one flexible link  101  connecting the lower enclosure  5 , located below the stack of enclosures, to the framework and limiting the travel of the lower enclosure in the upward direction. In the illustrated example, the limiting device  86  comprises two flexible links  101  connecting the lower enclosure to the framework. 
     It should be noted that the flexible links  101  could not be mounted on the lower enclosure  101 , but be mounted on any other enclosure of the stack. 
     The operation of the rearing device according to the second embodiment will now be described. 
     When the tide is high, as illustrated in  FIG. 17 , the float device  10  is completely submerged, and is at a distance from the water level. The flexible connection  95  is tensioned. The rearing enclosures  5  are in their extreme high positions. This position is defined by the limiting device  86 . 
     In the exemplary embodiments described above, this position is defined by the length of the flexible link(s)  101 , which are also tensioned. The float device  10  urges the upper rearing enclosure  5  upward, this urging being transmitted by each rearing enclosure  5  to the rearing enclosure immediately below it through the intermediate connections  97 . 
     When the sea is at an intermediate level between the high tide and the low tide, as a function of the length of the flexible connection  95 , the situation illustrated in  FIG. 16  is encountered. The float device  10  floats on the surface of the water, the flexible connection  95  being tensioned. The vertical movement of the water created by the waves causes a vertical movement of the float device  10 . When the float device  10  moves upward, it drives the upper rearing enclosure  5  through the flexible connection  95 , which in turn drives the enclosures located below upward through the intermediate connections  97 . 
     This upward vertical movement is limited, if applicable, by the limiting device  86 . In the exemplary embodiment described above, the upward movement is limited by the flexible links  101 . 
     When the water level drops, the float device  10  is driven downward. This gives slack to the flexible connection  95 , and the enclosures  5  are driven downward under the effect of their own weight. The downward movement of the upper enclosure  5  is limited, if applicable, by the limiting device  86 . In the exemplary embodiment described above, the downward movement is limited by the flexible link(s)  99 . The downward movement of each rearing enclosure  5  relative to the upper enclosure is limited by the length of the intermediate connections  97 . 
     When the tide is low, the rearing device is in the situation illustrated by  FIG. 18 . The rearing enclosures  5  are in their extreme low position, defined by the limiting device  86 . 
     In the exemplary embodiments described above, this position is defined by the length of the flexible link(s)  99  and by the length of the various intermediate connections  97 . The float device  10  floats on the surface of the water. The flexible connection  95  is not tensioned. 
     According to an embodiment variant illustrated in  FIG. 22 , the rearing enclosures  5  are connected to one another by intermediate connections  97  comprising a rigid member  117  and hinges  119  of the rearing enclosures  5  to the rigid member  117 . 
     The hinges  119  are configured to permit a pivoting of the enclosures  5  relative to the rigid member  117 . 
     The rigid member  117  is unique and shared by all of the intermediate connections  97 . They make it possible to connect all of the rearing enclosures  5  to one another. 
     In other words, the intermediate connections  97  are rigid spacers gathered to form a single rigid member. 
     This rigid member  117  is for example a bar or a tube substantially perpendicular to the rotation axes of the rearing enclosures. 
     At rest, the rigid member  117  is substantially vertical. 
     The hinges  119  are monobloc parts, typically made from plastic. They each include a pivoting connection  121  to the corresponding rearing enclosure  5 , and a rigid connection  123  to the rigid member  117 . 
     The pivoting connection  121  is made up of two half-rings  125 , intended to fit around the cylinder  65  formed on the distal edge  57  of the rearing enclosure  5 . The half-rings  125  are offset along the cylinder  65 . Together, they make up a bearing allowing a pivoting of the hinge  119  relative to the rearing enclosure  5 . 
     The rigid connection  123  includes two flanges  129  placed on either side of the rigid member  117 . A horizontal pin  131  is received in a through orifice of the rigid member  117 . They grip the flanges  129  against the rigid member  117 , such that the rigid member  117  is rigidly fastened to the hinge  119 . For example, additional nesting by tenon and mortise is provided between the flanges  129  and the rigid member  117 , so as to avoid any relative movement between the two parts. 
     In a variant, the rigid member  117  is mounted pivoting around the pin  131  relative to the hinge  119 . 
     In the present embodiment variant, the float device  10  is not necessarily connected to the upper rearing enclosure. 
     For example, the float device  10  is fastened to the rigid member  117 . 
     Furthermore, the limiting device  86  can cooperate with any rearing enclosure  5  in order to limit the upward and/or downward rotational travel of the rearing enclosures. It for example comprises at least one flexible link that can be connected to any rearing enclosure  5 . This or these flexible links make it possible to limit the rotational travel of the rearing enclosures both upward and downward. 
     In a variant, the intermediate connections  97  comprise several rigid members, each rigid member connecting several rearing enclosures  5  to one another. Each rigid member is for example of the type described above, and is connected to the corresponding enclosures by hinges of the type described above. 
     The invention can also be applied with rearing devices positioned on the tidal zone, when one wishes to set a superposition of enclosures in motion and/or to work with the same tide level over the entire surface of the tidal zone. This allows the farmer to make zootechnical choices: agitation frequency, amplitude of the movement, agitation duration. 
     As illustrated in  FIG. 19 , several devices according to the second embodiment can be positioned on the tidal zone at different depth levels, the float devices  10  of the various devices being adjusted to be placed at the same level. Thus, the flexible connections  95  of the various devices have variable lengths, as illustrated in  FIG. 19 . These lengths are chosen so that the respective flexible connections of the various devices are tensioned for substantially the same water level. 
     In a variant, the devices positioned on the tidal zone at different depth levels are positioned according to the first embodiment, the float devices  10  of the various devices being adjusted to be placed substantially at the same level. 
     It should be noted that, in the first and second embodiments of the invention, each rearing enclosure is, in a variant, equipped with its own float  103 , in addition to the float device  10 . Such a situation is illustrated in  FIG. 20 . The floats  103  are for example positioned in the enclosures  5 . They are sized to at least partially compensate for the mass of the aquaculture animals at the end of rearing. This makes it possible to limit the buoyancy of the float device  10  necessary for the movement, and therefore the forces transmitted by the float device  10  installed in the interval of the tidal range in case of storm, for example. This aspect is very important, because the cumulative effect of the floats depending on their number, arrangement and volume, leaves the farmer the possibility of definitively determining the ideal assembly perfectly adapted to his deep water site, knowing that the hydrodynamic conditions are invariable, while taking account of the storm risks, and therefore allowing him to consistently and regularly obtain the quality of product that he has chosen. 
     According to another embodiment variant applicable to the first and second embodiments, the float device  10  comprises not a single float, but a string  105  of floats. 
     Such an arrangement is illustrated in  FIG. 20 . This string  105  includes a plurality of floats  107 , mounted one after the other along a flexible link  109 , a lower end of which is secured to the flexible connection  95 . 
     Advantageously, the volume, and therefore the buoyancy, of the floats  107  increases from the upper end to the lower end of the flexible link  109 . 
     Such an arrangement allows a progressive, gentler and therefore longer action in the interval of the chosen tidal range. 
     This variant can be combined with the previous one (float  103  specific to each enclosure in addition to the float device  10 ). 
     According to a variant applicable to all of the embodiments, the connection  13  is not mounted on the proximal edge of each rearing enclosure  5 . If one considers the median plane of the rearing enclosure  5 , perpendicular to the lower bottom and parallel to the axes of rotation R 1  and R 2 , the connection  13  can connect any point located on one side of this median plane to the framework  3 . The float device  10  is preferably connected to any point located on the other side of the median plane. 
     Likewise, the flexible links can be connected to any point of the enclosure located on the side of the median plane opposite the connection  13 . 
     The invention has been described for a device in which the rearing enclosures  5  are connected to the framework by connecting members of the connecting rod type, creating a shearing force between the aquaculture animals and the enclosure under the effect of the vertical movement of the enclosures. However, the invention is also applicable to rearing enclosures connected to the framework by simple pivoting links about a single axis of rotation, as described in FR 2,576,484, or two systems of pivoting trays on which the rearing enclosures are placed, or to systems of cages containing many enclosures, said cages being able to pivot around an axis so as to ensure a movement of the enclosures similar to that previously described. 
     Another embodiment variant will now be described, in reference to  FIG. 21 . It is applicable to all of the embodiments previously described. 
     In this embodiment variant, the framework  3  does not rest directly on the sea bed  15 . The framework  3  is located slightly above the sea bed  15 . It is for example mounted on a carrier structure  111 , which rests securely on the sea bed  15 . 
     The carrier structure  111  is of any suitable type: table, gantry, etc. 
     It is rigidly fastened on the sea bed, or on the contrary is only ballasted so as to stay in place due to its own weight. 
     The carrier structure  111  bears one or several rearing devices  1 . Each framework  3  is mounted on the carrier structure  111  by any suitable means: rigid metal bars  113 , direct welds, flexible metal cables, etc. 
     The invention also relates to a method for rearing aquaculture animals at sea, the method comprising a step for installing at least one rearing device of the type described above at sea. 
     The framework  3  is placed on the sea bed. The length of the flexible connection  95  is chosen so that the float  11 , when the flexible connection  95  is vertically tensioned, is located in the intertidal zone. 
     Advantageously, several devices as described above are installed at sea in the installation step. The frameworks  3  of said devices are placed on the tidal zone at different respective levels. The lengths of the flexible connections  95  of said rearing devices are chosen so that, when said flexible connections  95  are vertically tensioned, the float devices  10  of the rearing devices are located substantially at the same level. 
     According to one exemplary embodiment, the limiting device  86  includes stationary stops to replace or in addition to the flexible links  87 ,  99 ,  101 . 
     These stationary stops are rigidly fastened to the framework  3 . Some of the stops limit the upward travel of the or each rearing enclosure  5  relative to the framework  3 , and other stops limit the downward travel of the or each rearing enclosure  5  relative to the framework  3 . 
     In the second embodiment, the stops are advantageously metal bars rigidly fastened to the framework, above and below the stack of rearing enclosures. 
     Such an arrangement is particularly well suited to the embodiment variant where the rearing enclosures are fastened on pivoting trays connected to the framework. 
     It should be noted that the combination of four complementary technical aspects makes it possible to obtain particularly interesting results. These four aspects contribute to imparting a shearing movement very effectively to the aquaculture animals that makes it possible to roll them over a surface and against one another so as to obtain a limitation of the growth by sequential rupture of the lace forming by strong fattening, cleanliness and shell shape that are irreproachable. 
     These four technical aspects are as follows.
         1. The use of an enclosure having an extensive and planar rearing surface for the aquaculture animals.   2. The use of a float device directly or indirectly connected to the enclosure that follows the sea level when the tide is at the level of the float device, transferring an incline variation from top to bottom and from bottom to top to the enclosure when the sea rises and falls, such that the aquaculture animals slide over the rearing surface; if applicable, the enclosure also follows the undulating movement of the waves, thus reducing the preceding movement and, if applicable, when the enclosure itself emerges, creating, owing to its bottom surface thus positioned at the air/water interface experiencing the effect of the wave striking the bottom of the enclosure, creates a washing effect by the water splashing through the meshes of the enclosure with an overpressure (well-known blowing effect of the waves in the rocky cavities on the seaside). This effect is particularly strong when the enclosure has a wide and flat lower surface, according to one favored embodiment of the invention.   3. The use of a fastener fastened on two axes, one on the enclosure and the other on the support of the enclosure, thus forming a connecting rod that converts the upward/downward movement created by the flow device into a shearing movement encouraging, in favor of their inertia, the movement of the aquaculture animals over the planar surface of the enclosure; this encourages the loosening of the aquaculture animals stuck on the enclosure by nacration during the tide periods without agitation of the enclosures.   4. The use of a limiting device making it possible to limit the vertical amplitude of the upward/downward movement due to the flow device in order to limit the preceding effects as a function of the zootechnical needs.       

     A synergy exists between these technical aspects, making it possible to achieve particularly good results. 
     However, it is not necessary to implement these four technical aspects jointly. The present patent application protects the implementation of aspect  2 . for enclosures able to be submerged in deep water, inasmuch as the float device is positioned in the tidal range zone. 
     This makes it possible to use zones for the rearing that cannot be used with rearing enclosures of the state of the art, while obtaining very good results for the agitation of the aquaculture animals. The implementation of aspects 1. and/or 3. and/or 4. in addition to aspect 2. further improves the results. 
     A parallel application protects aspects 2. and 3. used jointly. 
     Another parallel patent application protects the joint implementation of aspects 2. and 4.