FR2884110A1 - Crustacean e.g. crayfish, breeding device for e.g. aquarium type water tank, has garland defining housings with base presenting extension projecting with respect to housings, where openings of adjacent housings are differently oriented - Google Patents

Abstract

The device has structure intended to be placed in suspension in a water reservoir and constituted by a woven garland (4) defining open housings (5) intended to shelter crustaceans. The adjacent housings have openings oriented differently with respect to each other. The housings have horizontal or slightly inclined base presenting an extension projecting with respect to the housings. The reservoir has a base covered with a smooth and opaque PVC canvas.

Description

The present invention relates to a device for raising crustaceans and

especially crayfish.

  Patent application FR 2 693 874 discloses a device for raising crayfish in a closed and artificial medium and in particular in an aquarium-type tank or water tank. A suitable medium for the high species is created in this tank by regulating the pH, the temperature, the flow rate of the water and the temperature according to actual needs.

  The advantage of raising crayfish in a tank rather than in a breeding pond is that crayfish do not face pollution or natural predators such as fish or rats, and thus Disease risks are reduced. In addition, the tank offers by at least one transparent side a comfort of monitoring and observation for rapid health control. It makes it possible to intervene quickly in case of epizootic and to easily recover the crayfish for the sale. Moreover, such a device consumes little water and can thus be implanted in all regions without the need for river, lake or pond water.

  However, crayfish live at the bottom of the tank where they are spread over two dimensions and a tank culture therefore requires a large floor area. In addition, the density of crayfish on a surface and therefore the yields of livestock are limited by the cannibal character of crayfish.

  To increase the density of crustaceans in a breeding pond, it is known from patent document FR 2 602 951 to hang a filamentous structure, such as a net held by floats, diving into the water to the bottom. of the basin. The crustaceans then cling to this structure and divide themselves in three dimensions.

  The use of such a filamentous structure makes it possible to increase the density of crayfish raised for a given surface. The cannibalistic nature of crayfish is diminished by the fact that they may be further apart from each other. The cannibalistic nature still persists, with the rate of mortality or mutilation that it entails, because of the direct neighborhood between the crayfish or because the crayfish rush on it to look for food on the ground or fight when this food is too scarce.

  The object of the invention is to propose a device for raising crayfish in three dimensions which is improved in that it makes it possible to reduce the effects of the cannibal character and aggressiveness of crayfish on the profitability of breeding. .

  To this end, the invention relates to a device for raising crustaceans and in particular crayfish comprising a structure intended to be suspended in a water tank and on which the crustaceans cling, characterized in that the structure is constituted by a braided garland defining cells for receiving the crustaceans.

  The invention will be better understood on reading the description which follows and on examining the accompanying figures.

  This description is only indicative and not limiting of the invention.

  Figure 1 is a schematic representation of a crayfish rearing device according to the invention.

  Figure 2 is a schematic perspective view of a garland according to the invention.

  Figure 3 illustrates the manner of manufacturing a garland according to the invention.

  In Figure 1, there is shown a tank or water tank 1 of parallelepiped shape in which crayfish are raised. This tank 1 can be placed in a shed and the water can come from the rainwater collected by the roof of the shed. The water flows in a closed circuit between the tank 1 and a tank not shown by passing from the tank to the basin by a filtering system by variable size granulometry layers, The reloading basin contains limestone and algae to recharge and balance the water

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  carbonate, hydrogen potential, nitrate, nitrite, hydrometric titre. The recharge pond is also used for crayfish reproduction and juvenile fattening. The reservoir is more particularly reserved for the enlargement and ripening of crayfish.

  The tank 1 filled with water comprises a bottom 2 gently sloping and walls 3 for example transparent to allow a good visualization from the outside by the breeder. Several rows of wreaths 4 braided according to the invention are shown suspended on rods 1 O resting on the top his tank pers. The tufts of water in the water up to + 2 ° of the tank The garlands form suspended structures on which the crayfish can easily climb and cling, and it is also possible to hang the garlands on floats.

  It can be seen in FIG. 2 that each braided garland 4 is obtained by a folding of two strips (which is described below) and defines by folding a plurality of open housings 5 or cells that can each receive and house a crayfish. The dwellings are substantially pyramidal in shape with a substantially square base, the base corresponding to the opening of the housing and the sides of the pyramid to partitions of the housing.

  Each dwelling is directly adjacent to four dwellings and adjacent dwellings have openings oriented differently from each other. In this way, crayfish disposed in adjacent dwellings are not in proximity or direct contact but are separated by partitions of the garland housing. Crayfish separated from their congeners have a much less aggressive or cannibalistic behavior.

  Crayfish can remain lurking inside housing, especially when they moult and are very vulnerable.

  In addition, these dwellings have a substantially horizontal bottom or gently sloping and which has a slightly prominent advance compared to housing just above. Thus, when food is sent to the crayfish by dispersion from above the tank, this food flows slowly and is deposited in part on the bottom of each housing. In this way, the crayfish have enough food directly in their home and do not need to move to feed. This further limits the aggressiveness of crayfish.

  Finally, the bottom 2 of the tank is covered with a PVC tarpaulin so as to limit the risk of fighting. Crayfish skate on the smooth tarp and, feeling vulnerable and inferior in strength, refuse the fight.

  A garland 4 defining housing can be formed by braiding two strips of woven synthetic material folded on themselves. Figure 3 shows the method of manufacturing such a garland with two bands of the same width. The end of a first strip 6a is thus disposed on the end of a second strip 6b, the first strip 6a being disposed perpendicularly to the second strip 6b. The two strips are stapled with staples 7 at the point where they overlap, forming a square base 8. Then, the second strip 6b is folded and folded on the base 8, then the first strip 6a is folded and the flap on the base 8 and it starts again until the garland is completed. The last folding is stapled. Each square folded strip forms the bottom of a housing. It is possible to adapt the size of the garlands 4 and thus housing 5 to the crayfish size to account for their magnification. The garlands thus obtained are therefore flexible, light and washable, because of the material used to make them.

  The device according to the invention makes it possible to obtain a saving of space and an optimum yield by favoring the cohabitation of the crayfish on three dimensions.

  Crayfish fear the light. By covering the reservoir 1 to 90% by an opaque tarpaulin, it limits the brightness and can thus feed the crayfish more often, which improves their magnification and limits their aggressiveness. Of course, the garlands according to the invention can also be used in outdoor breeding ponds.

Claims (5)

  1) Device for raising crustaceans and in particular crayfish in the form of a structure intended to be suspended in a water tank (1) and on which the crustaceans cling, characterized in that the structure is a garland (4) braided defining cells (5) for receiving crustaceans.   2) Device according to claim 1, wherein each garland is mounted suspended from a float.   3) Device according to one of the preceding claims, wherein the garland defines adjacent cells that have different orientations.   4) Device according to one of the preceding claims, further comprising a smooth cover in the bottom of the tank (1).   5) Device according to one of the preceding claims, wherein the garland consists of two strips (6a, 6b) of plastic 20 braided by folding.