Protective device for animal breeding, such as the breeding of fish, mussels or mollusks

Protective device for animal breeding, such as the breeding of fish, mussels or mollusks, includes at least an inner cage that can be positioned in a body of water and which is formed from a net. This inner cage is dimensioned with a mesh width such that the animals to be bred are retained within the net. It is preferably totally surrounded by at least one outer cage spaced apart from the inner cage, and which is produced from a net made of thin wires and/or strands. The mesh width of the outer cage is greater than the mesh width of the inner cage, and it is thus guaranteed that predators cannot damage the net of the inner cage from the outside.

FIELD OF THE INVENTION

The invention relates to a protective device for animal breeding, such as the breeding of fish, mussels or mollusks, comprising at least one cage that can be positioned in a body of water and which is formed from a net and is dimensioned here with a mesh width such that animals to be bred are retained within the net.

BACKGROUND OF THE INVENTION

For fish farming, cages made of nets produced from elastic cords are used, as disclosed by publication WO-A-96/13973. The plastic nets made of a synthetic material are generally dimensioned with a cord diameter of, for example, between approximately 4 and 6 mm and relatively small mesh openings of 10 to 30 mm so that even young or small fish cannot escape. With these cages made of plastic nets, there is the risk that when the latter are assembled in open seas, predators such as sharks, seals or sea lions may rip open the cages from the outside with their mouth or will bump against said cages at a relatively high swimming speed and damage them so that the animals to be farmed may swim out in an undesirable manner at these damaged points.

OBJECT AND SUMMARY OF THE INVENTION

On this basis, the object underlying the present invention is to devise a protective device of the type specified at the start, by means of which, with simple assembly and improved securing, a long life span is achieved for the animals to be bred despite the predators. Furthermore, this protective device should enable easy cleaning.

According to the invention, this object is achieved by a protective device for animal breeding including at least one (inner) cage that can be positioned in a body of water and which is formed from a net and is dimensioned with a mesh width such that animals to be bred are retained within the net, and at least one outer cage that surrounds the at least one (inner) cage and is spaced apart from the at least one (inner) cage. The at least one outer cage includes a net made of thin wires and/or strands, with a mesh width of the net of the at least one outer cage being greater than the mesh width of the at least one (inner) cage. The at least one outer cage is designed to prevent predators from damaging the net of the at least one (inner) cage from the outside. The net of the at least one outer cage is formed from a wire mesh of individual helically bent wires, and the wire mesh is formed as a square diagonal mesh with rhomboid-shaped meshes and a three-dimensional mattress-like structure.

The cage positioned in the body of water is preferably totally surrounded by at least one outer cage spaced apart from the latter and which is produced from a net made of thin wires and/or strands, its mesh width being greater than that of the inner cage. By means of this outer cage, it is guaranteed that predators cannot damage the net from the outside and so cannot gain access to the inner cage, and the fish to be farmed cannot escape from the cage.

Very advantageously, the outer cage is clamped by longitudinal elements run to the bottom of the body of water so that the cage keeps its stable form even with strong currents in the body of water and so also retains more or less the required distance from the inner cage all around.

Further details of the protective device within the framework of the invention are defined in the dependent claims.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1-3show a protective device10for the breeding of animals in a body of water11. It is preferably suitable for breeding fish in the open sea, and it can be dimensioned with a length of over 120 m. However, it could also be used for other breedable animals such as mussels and/or other mollusks, and can also have a round cylindrical or similar form.

In the present exemplary embodiment a number of cages15are provided that can be positioned in the body of water11and which are formed from modules, only one of which is illustrated. These cages15are produced from a net16and are dimensioned with a mesh width15′ such that the animals to be bred in the latter cannot swim through.

According to the invention, this cage15is preferably totally surrounded by at least one outer cage20a distance away and which is produced from a net21made of thin wires22and/or strands, the mesh width of the net21being greater than that of the inner cage15and it being guaranteed by means of this outer cage20that predators cannot damage the latter from the outside.

The outer cage20is held at the top by a floating frame23, and corresponding fastening means18are provided. This frame23is sub-divided into twelve sections23′ into each of which an inner cage15can be inserted as a module. Needless to say, a different number of such sections or also none could also be provided.

The outer cage20is clamped by longitudinal elements24run to the bottom12of the body of water11so that the outer cage20keeps its stable form, even with strong currents in the body of water11, and so that the specified distance “a” from the inner cage15is also retained more or less all around.

The inner cage15is held to the frame23and/or the cage20, spaced apart from the latter, by connection elements17that are indicated. However, they can easily be removed from the outer cage20and be cleaned or replaced with new ones.

Advantageously, the net21of the outer cage20is produced from a wire mesh made of individual wires22that are bent helically. The wire mesh is formed as a square diagonal mesh with rhomboid-shaped meshes26and a three-dimensional mattress-like structure, the mesh widths26′ advantageously having dimensions of between 70 mm and 90 mm, whereas the mesh widths15′ of the net16of the inner cage are approximately 10 mm to 30 mm, this net16preferably being produced from plastic cords.

The wires22are preferably provided with a diameter of between 1 mm and 3 mm so that less accumulations of algae and mud form on the latter that have small surfaces and, moreover, can be cleaned easily.

In order to achieve sufficient strength, these thin wires22of the outer cage20are produced from high strength steel with a nominal strength of approximately 1,000 N/mm2or more. This can also be varied depending on the circumstances. In addition, the wires22are made of a rust- and saltwater-resistant material. It has thus surprisingly been shown that a long life span is achieved overall with this protective device10according to the invention.

The individual helically bent wires22of the wire mesh are connected to one another flexibly at their ends in pairs by loops22′ such that they do not form any cutting edges that injure the animals. For this purpose, after being bent round to form the loops22′, the wires22are additionally preferably provided with a number of nooses27wound around their own circumference. By means of these flexibly connected loops22′, it is guaranteed that this net21can be rolled up for transportation.

According toFIG. 3, the net21is preferably made up of a number of lengths, the latter being held together by connection means. Corrosion-resistant cords, pressure grips or the like are suitable as connection means. One such pressure grip28, known in its own right and made of corrosion-protected wire, is shown which has two arms28′ projecting out of a rounded base and which are each provided on their free end with a hook, the two hooks being directed towards one another.

The invention is sufficiently demonstrated by the exemplary embodiments described above. However, it could also be illustrated by other variations.

The cage or cages of the protective device according to the invention could also consist purely of shells wherein the net walls project to the bottom and no net or a net is only partially provided on the lower side.

Depending on the circumstances in a body of water, the outer shell could be formed purely by a wall if, for example, the inner cage were positioned in a harbour-type environment.

Instead of the upper floating frame23, with smaller cages in particular, just one cord or the like encompassing the cage could also be provided.